An Assessment of the National Institute of Standards and Technology Programs Fiscal Year 1994 (1994)

Samuel A. Werner, University of Missouri, Columbia, Chair

C. Denise Caldwell, University of Central Florida

Stuart J.B. Crampton, Williams College

William C. Eckelman, National Institutes of Health

Leopoldo M. Falicov, University of California at Berkeley

Louis C. Glasgow, E.I. du Pont de Nemours & Co., Inc.

Andrew U. Hazi, Lawrence Livermore National Laboratory

Klaus B. Jaeger, Lockheed Missiles Space Company, Inc.

Anthony M. Johnson, AT&T Bell Laboratories

Andrew Kaldor, Exxon Research and Engineering Company

James E. Lawler, University of Wisconsin

Edwin C. McCullough, Mayo Clinic/Foundation

Robert F. Morrissey, Johnson & Johnson Associates, Inc.

David A. Shirley, Pennsylvania State University

Robert F.C. Vessot, Smithsonian Astrophysical Observatory

Philip Wychorski, Eastman Kodak Company

Ex Officio Member

David E. Pritchard, Massachusetts Institute of Technology, Chair, Joint Institute for Laboratory Astrophysics Subpanel

This report is an assessment of the fiscal year 1994 activities of the Physics Laboratory at NIST. It is based on site visits to the laboratory by individual panel members in March and April 1994, on a meeting of the full panel in Boulder, Colorado, on May 2-3, 1994, on the annual report of the laboratory, and on many research papers and reports provided to individual panel members.

The mission of the Physics Laboratory is to support U.S. industry by providing measurement services and research for electronic, optical, and radiation technology by pursuing directed research; developing new physical standards, measurement methods, and data; conducting an aggressive dissemination program; and collaborating with industry to apply its discoveries and commercialize its inventions.

The Physics Laboratory addresses the above mission through the fundamental triad of standards, measurement, and data within the context of internationally competitive research. The quality of the laboratory's service to industry and the public at large stems from its breadth, vigor, and excellence in its research programs. In recognition of NIST's obligation to assure that the maximum public benefit be derived from its research, the laboratory pursues a vigorous dissemination program, including measurement services, workshops, publications, and collaborations with industry, universities, and other agencies of government. The laboratory is vertically integrated, spanning the full range of programs from tests of fundamental postulates of physics through generic technology to the more immediate needs of industry and commerce. Its constituencies are broadly distributed throughout industry, academia, and government and include the other laboratories of NIST.

The laboratory's focus on atomic, molecular, optical, and ionizing radiation physics reflects the importance of these disciplines in developing new measurement technologies in anticipation of long-term needs of U.S. industry. For example, both past and present methods for standardizing length, frequency, and certain aspects of radiation follow from the increased refinement and sophistication in spectroscopic measurement techniques.

To strengthen the connection between the performers of directed research and the industrial developers of advanced technologies, scientists in the laboratory work with various industries and other laboratories of NIST to develop new measurement technologies that can be applied to communications, defense, energy, environment, space, health, microelectronics, radiation, and transportation. These associations are facilitated by Cooperative Research and Development Agreements (CRADAs), industrial research associates (a new program), trade and professional committee participation, and consultations with numerous industries.

The laboratory has identified four strategic areas where its experience and expertise can best contribute to the scientific community and immediate national needs by providing measurement methods, instrumentation, standards, and data:

1. Electronic and magnetic devices—to develop innovative measurement methods and techniques of use to the electronics industry for device characterization and electronic information and communication;

2. Optical technology—to provide the national basis for optical radiation measurement and to develop optical measurement systems for industrial and environmental needs;

3. Radiation applications and control—to support innovative, effective, and safe use of radiation by providing standards and measurement assurance services, developing and evaluating new radiation measurement methods, and providing critical data; and

4. Fundamental physical quantities—to improve the definitions and physical realizations of base and derived International System of Units (SI) and to pursue opportunities for new determinations of fundamental physical constants.

The current total budget of the Physics Laboratory for fiscal year 1994 is $46.2 million, of which 64 percent, or $29.6 million, is congressionally appropriated money (NIST Scientific and Technical Research and Services, or STRS, funds). This budget is up about 9 percent from fiscal year 1993. About 24 percent of the budget comes from other agency (OA) support. The projected budget for fiscal year 1995 is up only incrementally to about $47 million. For fiscal year 1996, however, the projected budget will increase to $53 million, which will include additional funding for the laboratory to take the lead role internationally in new fundamental standards work.

The current permanent staff in the laboratory is 271 (including 15 postdoctoral fellows), of whom 84 percent are scientific and engineering personnel. During fiscal year 1994, the laboratory is host to 145 guest researchers. About 75 percent of the professional scientific staff are physicists, 16 percent are chemists, and 9 percent are engineers. Technicians account for 6 percent of the total staff, 8 percent are clerical, and 2 percent are administrative.

The Physics Laboratory is organized into eight divisions: Electron and Optical Physics, Atomic Physics, Molecular Physics, Radiometric Physics, Quantum Metrology, Ionizing Radiation, Time and Frequency, and Quantum Physics. The last two of these divisions are located in Boulder, Colorado. The Quantum Physics Division is reviewed biennially (see attachment below). Three of the divisions, namely Radiometric Physics, Ionizing Radiation, and Time and Frequency, have a large service component responding to various industrial, public, and governmental needs. External and OA support is substantial, in the range of 60 percent of their budgets. The Office of Electronic Commerce in Scientific and Engineering Data is being established by the Physics Laboratory to increase the efficiency of electronic dissemination of databases.

This organizational structure is reasonably efficient and functional in responding to national scientific and technological needs. Cross-divisional and interdisciplinary responses to these needs are common within the laboratory. The panel found the following areas in the Physics Laboratory to be of preeminent competence: time (the atomic clock: NIST-7); ion/atom cooling; surface magnetism; scanning tunneling microscopy (STM); laser physics and laser stabilization; vacuum ultraviolet radiometry and calibrations; infrared spectroradiometry; femtosecond molecular dynamics; atomic, molecular, and radiation data centers; radionuclide environmental radioactivity standards; neutron measurements and standards; and dosimetry of ionizing radiation.

Currently, the laboratory has 110 industrial collaborations, about 25 supported by CRADAs. It maintains 6 data centers and provides 98 calibration services and 28 standard reference materials (SRMs) to industry. The panel considers these figures evidence that the laboratory's strategic plan is succeeding and will allow response to future technological changes.

A number of facilities and groups in the Physics Laboratory provide critical services, data, materials, and calibrations to U.S. industries, other agencies, and institutions. In certain cases, they are largely supported by specific OA funding. When this funding is reduced or withdrawn, the ability of NIST to fulfill its responsibilities to its national clients is placed in jeopardy. Laboratory management must plan to assure the stable funding of such projects.

With the increasing emphasis on NIST's role in providing services and technical assistance to U.S. industry, and with the increasing funding being provided by the government for this purpose, it is essential to develop various methods to assess the impact of this effort on the success and competitiveness of U.S. industry in future years. The panel suggests using the report Setting Priorities and Measuring Results at the National Institute of Standards and Technology (NIST, Gaithersburg, Md., January 1994) as a guide to documenting the Physics Laboratory's involvement with and impact on U.S. industry.

As the projected budget of NIST increases in the next few years, management intends to replace OA funding with STRS funding, thus shifting the balance from the current 64 percent STRS support to 75 percent. As this shift in funding occurs, NIST management has decided to keep the number of permanent NIST staff capped at its current level. If the laboratory's budget grows while staff remains capped, greater alliances with university researchers might be appropriate. This is particularly important, since as the country shifts its scientific attention and public support away from military and defense applications toward commercial and civilian technologies, keeping the national scientific and engineering personnel resource pool at adequate levels could prove to be the decisive factor in ensuring U.S. strength in worldwide industrial competitiveness.

The breadth, effectiveness, and willingness of the scientific staff of the Physics Laboratory to help U.S. industry meet its competitive challenges are discussed in some detail in the technical assessments of the divisions. The panel was generally pleased with the laboratory 's technical programs, and descriptions of programs it found of particular note are given below.

A CRADA has been established between the Oriel Corporation and NIST to collaborate on the characterization of pencil-type mercury discharge lamps. The results of this project will allow these inexpensive lamps to be used in applications that lacked low-cost, adequate standards for color and intensity. Such standards are critical in calibrating instruments that measure blood chemistry, lead levels in drinking water, and octane in gasoline. Several properties of these lamps will be addressed, including the spectrum of light emitted and the effect of temperature and lifetime on lamp performance. Facilities within the Physics Laboratory and the Chemical Science and Technology Laboratory (CSTL) will be employed for this work.

The Electron and Optical Physics Division has successfully demonstrated a new laser process to fabricate nanometer-size metallic structures on a surface. Experiments focused a beam of chromium atoms in a laser standing wave, which grazes across the surface of a silicon wafer.

The nodes of the standing wave act as an array of atom lenses, focusing the chromium atoms into a series of lines as they deposit onto the surface. The lines are 34 nm high, 65 nm wide, and spaced 213 nm apart. Large arrays of structure could be fabricated by this method using a two-dimensional standing wave to make an array of quantum dots. Eventual applications include the fast and accurate fabrication of nanostructure devices for microelectronics and micromagnetics. This experiment also provides a direct means of transferring an optical wavelength standard to the dimensions of nanostructures.

The Molecular Physics Division is collaborating in the search for environmentally acceptable alternatives to chlorofluorocarbon refrigerants. Mixtures of hydrocarbons are being considered, which will allow tailoring of vapor pressure, lubricant solubility, and flammability ranges. Hydrocarbons and hydrocarbon mixtures have properties that are strongly correlated to their permanent electric dipole moments, which are now listed in the NIST Standard Reference Database 23, “NIST Refrigerant Properties Data Base.” High-resolution rotational spectroscopy to determine dipole moments and benchmark modeling calculations are being carried out on two families of fluorinated ethers in the Molecular Physics Division in collaboration with the Thermophysics Division (CSTL).

The laboratory staff again received many awards and honors since the fiscal year 1993 assessment, including the 1993 Distinguished Scientific Achievement Award from the Health Physics Society, the 1993 Computer Application in Nuclear and Plasma Science Award, election to the presidency of the International Commission on Illumination, election to the vice-presidency of the International Committee for Radionuclide Metrology, the American Physical Society's Schawlow Prize, and the recognition of the atomic clock (NIST-7) as one of the year's 100 most significant achievements by the editors of Popular Science magazine.

The following are the panel's recommendations for the Physics Laboratory as a whole.

• The panel recommends that a comprehensive list of “at-risk” facilities or groups providing critical services, data, materials, and calibrations to industry and other organizations be compiled and internal STRS funding be provided on a priority basis to these projects to ensure their stable long-term support. Progress in this effort should be reported to the panel at its fiscal year 1995 assessment.

• The panel recommends that the Physics Laboratory track the impact of a few selected ongoing services or collaborative activities with U.S. industries over the next 5 years. This tracking will involve the periodic accumulation of statistical, financial, and new-product-generation data. A summary of this activity should be part of the laboratory 's annual report, along with an expanded report on interactions with industry and the impact of these efforts.

• As funding increases but staff remains capped, the Physics Laboratory should consider alliances with U.S. universities to enhance NIST-connected new technology development with support of postdoctoral fellows and young faculty, both on-site at NIST and at their home universities.

The panel is pleased with the laboratory director's written response to its fiscal year 1993 recommendations and with actions taken since its previous assessment. On the whole, the response to the panel's recommendations has been serious and responsible. Given below are some of the panel's fiscal year 1993 recommendations for the laboratory as a whole (quoted from the fiscal year 1993 assessment), with the Physics Laboratory's responses.

• “The panel recommends that the Physics Laboratory extend the ‘Advanced Algorithms, Software, and Applications' proposal to include the development of on-line visualization and a state-of-the-art physics computational center to support the database effort. This extension could have a major impact on NIST's general responsibilities to provide to industry such scientific and technical data as plasma radiation data and atomic energy level data” (p. 148). The Physics Laboratory has established an Office of Electronic Commerce in Scientific and Engineering Data to make scientific, engineering, and technical codes, standards, and regulatory data available to U.S. industry in a usable, accessible, and unified manner.

• “The panel recommends that the advanced optical technology initiative be pursued as a high-priority program, not only because it supports the mission of NIST and will strengthen NIST's ability to interface properly with its extramural Advanced Technology Program, but also because NIST is the only place in the United States where the necessary expertise exists in optical measurement and instrumentation techniques to significantly advance optical technology” (p. 148). The initiative on advanced optical technology was not included in the fiscal year 1995 budget. However, some of the projects are addressed in the NIST director's fiscal year 1996 initiative on measurements and standards for emerging instrumentation industries. Plans for an interlaboratory fiscal year 1997 initiative on photonics and optical technology are now under way.

• “The panel recommends that the laboratory's name be changed to the Physical Sciences and Technology Laboratory. This name would not only more accurately reflect the laboratory' s activities and responsibilities but also would be more in parallel with the names of other NIST laboratories” (p. 148). This recommendation, along with options for reorganizing the laboratory into fewer, more vertically integrated divisions, is still under heated discussion.

The mission of the Electron and Optical Physics Division is to develop measurement capabilities needed by emerging electronic and optical technologies, particularly those required for submicrometer fabrication and analysis or for which absolute radiometric measurements are critical.

The Electron and Optical Physics Division pursues two activities that have strong technical links but address different customer bases: development of basic measurement techniques and provision of calibration and measurement services. The ways these two activities are pursued are distinct.

The service component is charged to continually improve the effectiveness with which it addresses customer needs. Its performance in this regard is judged by polling its customer base. With the exception of the Synchrotron Ultraviolet Radiation Facility (SURF) III upgrade, programs have addressed needs for more accurate or reliable transfer standards or the needs of the SURF II user community or other specialized sectors such as the extreme ultraviolet (EUV) optics community; they have thus been formulated as appropriate technical responses to needs that the division has been able to identify on the basis of close and regular interaction.

For the SURF III upgrade, the division is responding to the broadly stated priorities of the Council on Optical Radiation Measurement (CORM) and also to an internal NIST impetus to transform the basis of absolute radiometry from the EUV through the infrared spectral region. The division is looking well ahead of immediate customer requirements and is to some extent also trying to make advances in basic measurement methodology. The basic goals of the SURF III upgrade are to provide the absolute accuracy called for by CORM.

Fiscal year 1994 funding for the Electron and Optical Physics Division is estimated at $6.2 million, of which $5.0 million is from STRS. The division has 29 technical staff and 3 postdoctoral fellows and was host to 17 guest researchers during fiscal year 1993.

Developments in modern, high-technology industry continue to realize devices at everdecreasing length scales. Characterization, quality control, and even production demand measurement at the same scale. Industrial competitiveness requires measurement techniques at the next smallest length scale. The strategic plan of the Electron and Optical Physics Division addresses the challenge of measurement at the next smallest size. The focus on EUV optics (through SURF and through the nanodetector) targets vital needs in the development of appropriate optical elements and detectors in this region. Magnetic imaging and surface characterization and fabrication programs target vital needs in the search for ever better and smaller nanostructures. Both are combined in the proposed plan in such a way as to offer much needed current measurement resources and provide for future needs.

Far Ultraviolet Physics Group. The planned upgrade of the SURF II electron storage ring capitalizes on the unique strength of the facility and its accurately definable character of radiation and provides for major improvements and extensions of the use of SURF as an absolute radiometric source. The generation of photons at higher energies, particularly in the water window, opens up new possibilities for microscopy when combined with the newly developed EUV microscope. At the same time, these changes will preserve and even improve the role that SURF has traditionally played as a calibration source for detectors and a general user facility for research groups from around the country.

SURF has long served as the national basis for radiometry in the 5- to 200-nm spectral region. The planned upgrade will achieve two very important goals. First, it will improve the accuracy of existing calibrations by an order of magnitude within this region, reaching as low as 0.1 percent. Second, and even more basic, it will extend the range over which calibrations can be performed, down to 2.4 nm through an increase in the energy of the electron beam and into the infrared through the better characterization of radiation in this region. The collaboration that is developing between this group and the Radiometric Physics Division to connect the SURF source to the cryogenic radiometer is particularly noteworthy because of its inherent possibilities. In the near term (about 3 years), the new SURF III should emerge as the basis of a unified radiometric scale from the infrared through the EUV. In the long term, an optical definition of temperature through SURF and the Planck relationship is also possible. These quantities are important to the industrial community and are discussed in more detail in the assessment of the Radiometric Physics Division.

SURF has long had a service role in the calibration of instrumentation for the government and the industrial community. Both calibration beamlines are used on a regular basis. The new double-grating monochromator, which has been under development for several years to calibrate photodiodes for use as transfer standards, is now in routine use on one of these beamlines. The completion of this effort is very positive, as this is one of the primary activities of SURF that will benefit from the upgrade. The companion program in the development of new silicon photodiodes has also made significant advances since the fiscal year 1993 assessment.

Other efforts on the beamlines around the SURF machine are proceeding steadily now that construction for the reflectometer beamline has been completed. There is now activity on the high-throughput toroidal grating monochromator, and interaction with researchers from U.S. universities has been very productive. These interactions might increase once the energy of the electron beam energy is increased to make more photons available at higher energy. It is important that these interactions be maintained, since they provide invaluable contact and exchange of information and experience. The panel views the director 's decision to maintain one option for a high-energy beamline as very encouraging.

Electron Physics Group. The increased funding in the Electron Physics Group has been reflected in good productivity and exciting research. Highlights are given below.

Chromium atoms focused by laser have been used to create periodic nanostructures on a surface. The high-quality lithographic specimens thus created and examined by means of atomic force microscopy have received considerable publicity and have been reproduced in internal, national, and international publications. The group has also measured spin-polarized electron

scattering from laser-excited chromium, including complete resolution of the chromium quantum states.

Scanning tunneling microscopy studies have been expanded to encompass fundamental research and practical applications, including development of a low-temperature STM, studies of local structures, use of STM as a potentiometer, possible use of STM to study luminescence on the atomic scale, and development of a magnetized STM.

Scanning electron microscopy with polarization analysis (SEMPA), a technique pioneered and developed by this group, has been extended to new fundamental and practical applications in collaboration with Allied Signal. In particular, SEMPA is used to study defects in magnets, magnetic domains, and the performance of magnets.

Work has progressed considerably in magnetic multilayers, particularly in understanding coupling mechanisms between ferromagnetic iron films separated by nonmagnetic materials such as gold, silver, or chromium. The details of the electronic structure of the spacer metals are clearly revealed in SEMPA experiments. Theoretical studies have also been performed on the geometrical properties of the Fermi surface of chromium and how it influences the behavior of chromium as a spacer in magnetic multilayers.

Control of the growth of thin films at the single atomic layer level by molecular beam epitaxy and examination by reflection high-energy electron diffraction have shown some fascinating growth effects that indicate unexpectedly complicated behavior.

Photon Physics Group. This group has the responsibility of maintaining the only existing high-photon energy reflectometer in the United States. The group provides an indispensable service to government, university, and industrial organizations involved in development and production of optical elements for use in the extreme ultraviolet and is working with several small firms that are developing optics for imaging of EUV radiation. Although the reflectometer was first developed in support of lithography, its actual use is much broader and affects all areas of imaging at the high-energy end of the optical spectrum. A current interest is the development of multilayer mirrors to provide high reflectivities at these high energies. The necessary measurements to determine the optical quality of a particular mirror to the necessary accuracy can be made only at this facility. Since the fiscal year 1993 assessment, the SURF beamline designated for this activity was completed, and it is now in full operation. The work is currently restricted by the small vacuum chamber for mounting optics, which limits the size of elements that can be measured. The chamber being built, however, should overcome this limitation; this new capability should be implemented in as expedient a manner as possible.

A researcher's death has ended the collaboration on x-ray fluorescence studies; this collaboration was an outgrowth of involvement with a beamline at the National Synchrotron Light Source (NSLS). In light of this and because this work is being vigorously pursued by others at the Advanced Light Source at Berkeley, this effort was redirected into the implementation of the new nanodetector, a unique soft x-ray microscope. The panel concurs with this action. Construction of the microscope is now virtually complete, and testing should begin soon. A number of directions have been proposed by the Photon Physics Group for possible extension of the nanodetector. These include the possibility of in situ characterization of thin films during the deposition process and biological imaging within the water window. These new possibilities are intimately connected with the new capabilities of SURF. Any one of the directions that the group suggests has potential, but it will be important to identify an area and make plans to pursue

development in that area. No matter what decision is made in this regard, it is important to note that the resolution of the nanodetector is currently limited by the ability to focus the secondary electrons; thus, research to find new photocathode materials that allow better imaging of secondary electrons is vital.

The following are the panel's recommendations for the Electron and Optical Physics Division.

• Careful scheduling and planning should be used to minimize the time in which the SURF ring is apart for insertion of new magnets and a vacuum chamber and for building two new beamlines for the radiometry activity.

• It is important for the Far Ultraviolet Physics Group to identify and plan directions in which to pursue extension of the SURF radiometer.

Given below are some of the panel's fiscal year 1993 recommendations for the Electron and Optical Physics Division (quoted from the fiscal year 1993 assessment), with the division's responses.

• “The panel recommends additional emphasis on making the toroidal grating monochromator operational” (p. 148). The toroidal grating monochromator (TGM) on Beamline 8 has been in productive use by members of the Surface and Microanalysis Science Division of the CSTL. The other TGM at SURF II, which is on Beamline 1, is planned for use by that division, but installation of necessary end-station equipment has been delayed by difficulties in procurement and logistics.

• “As new synchrotron radiation facilities come on-line, the panel recommends that managers of the Synchrotron Ultraviolet Radiation Facility (SURF) project elucidate the advantages that make SURF a unique measurement tool. In particular, future plans for SURF should capitalize on the unique advantages of the optical quality of SURF's radiation” (p. 148). A long-range plan for SURF II has been devised by the Electron and Optical Physics and Radiometric Physics Divisions, in consultation with the NIST deputy director. Its goal is to place SURF II at the core of an absolute radiometric system that represents the state of the art in sources and detectors. This plan provides a unified approach to existing NIST radiometric efforts and extends radiometric capabilities to regions of growing importance to industry and science. It is indeed predicated on the unique orbital properties of SURF II, which are being refined rather than altered. The NIST deputy director has allocated substantial funds for this project.

• “The panel recommends that long-range planning be undertaken for the Electron Physics Group” (p. 148). The Physics Laboratory as a whole has indeed increased its attention to long-

range planning during fiscal year 1994, and this group has been among the most effective contributors to that process.

The Atomic Physics Division carries out experimental and theoretical research into the spectroscopic and radiative properties of neutral and highly ionized atoms; provides measurement and data support for specific needs in such technological and industrial areas as the processing of materials by plasmas, spectrochemistry, commercial and residential lighting, laser development, and fusion-plasma diagnostics; develops well-defined atomic radiation sources as radiometric or wavelength standards; studies the physics of laser cooling and electromagnetic trapping and manipulation of neutral atoms and ions; and critically evaluates and compiles spectroscopic databases on wavelengths, energy levels, transition probabilities, and linewidths and shifts.

The work of the Atomic Physics Division is planned to proceed mainly in four technical directions.

1. Determinations of high-accuracy atomic properties and related critical compilations of atomic data. Advanced atomic structure data, especially for species of industrial interest, will be produced with the new high-resolution Fourier transform spectrometer (FTS), with the Electron Beam Ion Trap (EBIT) Facility, with ultracold trapped atoms, and using sophisticated theoretical atomic structure methods. The division is also pursuing critical spectroscopic data compilation work, as well as the establishment of a comprehensive spectroscopic database.

2. Development of optical-lattice technology to produce complicated patterns to assist in the creation of permanent structures of small feature size. Similarly, the division is developing an ion extraction capability on the EBIT source to study the interaction of highly charged ions with surfaces and the generation of nanostructures.

3. Measurement of the properties of plasmas typically used in production-line plasma etching setups. The division will develop nonperturbative diagnostic techniques to monitor the long-term stability and reproducibility of such plasmas by exploring laser-induced diagnostics.

4. Research on atomic fountain clocks in collaboration with the Time and Frequency Division to explore these devices as a new class of ultraprecise atomic clocks.

Fiscal year 1994 funding for the Atomic Physics Division is estimated at $4.7 million, of which $3.7 million is from STRS. The division currently has 19 technical staff and 5 postdoctoral fellows and was host to 25 guest researchers in fiscal year 1993.

The Atomic Physics Division has produced a well-thought-out plan to develop its resources in the three fiscal years 1994 through 1996, containing four action items related to identified industrial needs: (1) improved optical and plasma devices for illumination, medical and spectrochemical applications, and fusion research; (2) atomic-scale fabrication and lithography of electronic and biotechnology devices; (3) improved production-line plasma sources for semiconductor processing; and (4) improved time, length, and frequency standards.

All four items with their objectives and timetables are sensible and achievable. There is, however, a lack of coordination with the Time and Frequency Division on the timetable and urgency of development of the cesium (Cs) atomic fountain clock. The panel advises the two divisions to coordinate their aims and timetables and act as a single unit.

Atomic Spectroscopy Group. The Atomic Spectroscopy Group has had numerous achievements since the fiscal year 1993 assessment, some of which are discussed below. The group is poised to take advantage of two major new instruments during the next few years: the EBIT and the FTS. The group is now contributing important spectroscopic data on highly ionized atoms, which, among other uses, supports the goal of thermonuclear fusion power. The group's worldwide preeminence in research on highly ionized spectra is evidenced by its extraordinary publication record and by major prizes and awards. Important accomplishments include work on the spectra of 27 through 34 times ionized tungsten. The successful completion and initial operation of EBIT provide a major improvement in NIST facilities for work on highly ionized spectra. The panel does not consider it in the national interest to shift personnel from work on highly ionized spectra using EBIT to work on neutral and singly ionized spectra using the new FTS.

Research using the FTS will serve the needs of industry for basic spectroscopic measurements on neutral and singly ionized atoms and molecules. Very specific and urgent needs of the lighting industry have been identified, and a CRADA is under negotiation with General Electric. Accurate absolute atomic transition probabilities for neutral and singly ionized rare-earth elements have been requested. These spectroscopic measurements are needed for modeling and diagnosing high-intensity discharge lamps. The new FTS is uniquely suited for this task. It has numerous important advantages for measurements on the rich rare-earth spectra, including a limit of resolution as small as 0.0025 cm⁻¹, absolute wavenumber accuracy of 1 part in 108, extremely broad spectral coverage from the ultraviolet to the infrared, and the capability of recording 1 million fully digitized spectra in 1 hour. The FTS also makes a simultaneous measurement on all spectral resolution elements from the ultraviolet to the infrared. This advantage over sequentially scanned monochromators makes the FTS insensitive to drifts in source intensity while performing spectroradiometric measurements. The technical advantages of the FTS and the group's excellence in spectroradiometric measurements provide a great opportunity to serve the needs of the lighting industry. The panel applauds the decision of the Physics Laboratory director to make the initial investment in the FTS.

The Atomic Spectroscopy Group's contribution to industrial scientists and other researchers by providing a critically evaluated spectroscopic database deserves special mention.

No university or corporate laboratory can provide this service. The committee applauds the Physics Laboratory director's increased commitment to the database effort. The panel strongly endorses the group's efforts to transfer existing databases to an electronic format, so they will be more widely accessible using the National Information Infrastructure.

Plasma Radiation Group. The assembly and first successful operation of the NIST EBIT is a major milestone for the Plasma Radiation Group and the Atomic Physics Division. The observation of the spectrum of 46 times ionized barium in EBIT is dramatic evidence of this achievement. NIST is uniquely suited to build and operate EBIT. The project is too expensive for most university laboratories and too long term for most corporate laboratories in today's research climate. The EBIT project will meet an important national need for continued research on the spectra of highly ionized atoms for diagnosing fusion plasmas. The construction of EBIT by the Plasma Radiation Group is important because EBIT provides an “in-house” capability for research on highly ionized spectra. The EBIT also provides ions in an environment suitable for precision spectroscopy.

The EBIT project encompasses a good mix of long-term basic research on spectroscopy, which supports thermonuclear fusion power, and somewhat shorter term research on surface modification using highly charged ions. The panel encourages some highly speculative research, such as current work on surface modification using highly charged ions. The panel also applauds the laboratory director's increased commitment to the EBIT project.

The Plasma Radiation Group has made steady progress on the Gaseous Electronics Conference (GEC) reference reactor. This group is uniquely qualified to perform accurate absolute emission and adsorption spectroscopy on the radio frequency plasmas in the GEC reference reactor. Careful spectroscopic studies are needed to develop a more quantitative understanding and improved predictive capability for radio frequency plasmas used by the semiconductor industry.

Laser Cooling Group. The Laser Cooling Group plays an important role in the division's support of innovations in frequency standards, high-resolution atomic spectroscopy, and optical manipulation of matter. The group concentrates on developing new fundamental techniques for cooling and trapping neutral atoms and assists in their application to new technology by collaborating with groups within and outside NIST and by training guest workers from other groups. The group has a good balance between extending fundamental knowledge of this new branch of physics and transferring this knowledge to technology.

This group is recognized worldwide as a leader in developing new techniques for cooling and trapping neutral atoms and in exploiting these techniques to make new kinds of fundamental measurements in atomic physics. Because thermal motion of atoms often limits the precision with which their properties can be measured, the ability to cool gases of atoms by factors of 100 million or more in temperature has driven the precision of many atomic measurements to unprecedented levels. In addition to new levels of precision, which will affect precision measurements of fundamental constants and new types of studies of fundamental atomic properties, laser cooling and trapping are likely to substantially affect technology. Almost certainly, the first effect will be in the area of frequency metrology, an area in which this group is already active.

The group's most recent achievements include successfully transferring laser photon momentum to atoms without exciting the atoms to new levels, thereby preserving the coherence of the atomic states. Manipulating atoms without destroying coherence is important to processes in which beams of atoms are first separated and then brought back together to produce interference effects. The group has taken another step toward developing a cesium atomic fountain clock by producing a three-dimensional optical lattice of trapped cesium atoms. Four converging light beams form an interference pattern that traps cesium atoms in the regions of high light intensity. The trapped atoms are localized to one-twentieth of a wavelength and separated by distances of the order of 200 nm, which can be varied by tuning the lasers. The trapped atoms have been cooled to a new record low of 0.6 microkelvin. The very low transverse velocities of the lattice atoms make them an ideal source of atoms for a cesium atomic fountain clock. The development of such advanced frequency standards is crucial to the international competitiveness of several sectors of U.S. industry, most notably communications.

Another step toward the adaptation of laser cooling techniques to frequency metrology has been the measurement of the lifetime of a long-lived metastable state in atomic xenon. This state will play an important role in the operation of a ¹³²Xe optical clock, which will be developed in the same magneto-optical trap apparatus in which the measurement of lifetime was made. The techniques developed to measure the very long lifetime of about 43 seconds without interference from processes other than decay may prove useful because they push the limits of accuracy of atomic theory calculations. Indeed, a discrepancy between this measurement and theoretical predictions has already led to a refinement in the theory. This work is being performed under a CRADA with Rincon Research Corporation.

Finally, the group has exploited the properties of very cold atoms to develop a spectroscopic technique that gives very high precision determination of the structure of very weakly bound, long-range sodium molecular states. Such states extend the region over which molecular potentials can be tested.

The preeminence of the laser cooling group derives from its pioneering achievements, its successful collaborations with other groups, and its success in disseminating knowledge of these new techniques. Its collaborations include one with a university group to demonstrate trapping atoms with microwaves, a collaboration within NIST to develop a neutral atomic fountain clock, another to match theory to experiments on colliding cold atoms, and a National Science Foundation-sponsored collaboration with groups both within and outside NIST to develop new lithographic and other applications for manipulation of matter by light. In addition to their leadership in developing new physics and technology, members of the group have played an important teaching role by organizing conferences, giving invited talks and summer school tutorial courses, writing a popular review article, serving as guest researchers at other laboratories, and hosting guest researchers from other laboratories. A member of the group organized the 1993 Atomic Physics Gordon Conference. Since the fiscal year 1993 assessment, the group has attracted 4 National Research Council (NRC) postdoctoral fellows and 11 guest researchers.

The following are the panel's recommendations for the Atomic Physics Division.

• Since a group in Europe has seized the lead in developing a cesium atomic fountain clock frequency standard, the Laser Cooling Group should move ahead rapidly to demonstrate a successful cesium atomic fountain clock, developing new techniques to be used by scientists in the Time and Frequency Division to produce a prototype microwave frequency standard. The Atomic Physics and Time and Frequency Divisions should coordinate their aims and timetables and act as a single unit.

• The Physics Laboratory should give high priority to amortizing its investment in the FTS by assuring that it is properly staffed. Effective use of the FTS will require continuity that probably cannot be provided by a sequence of postdoctoral associates.

Give below are the panel's fiscal year 1993 recommendations for the Atomic Physics Division (quoted from the fiscal year 1993 assessment), with the division 's responses.

• “The panel recommends that the Atomic Radiation Data Group secure the assistance of a computer scientist with expertise in database software for the efficient implementation of its database efforts ” (p. 149). At the time of the assessment, the Physics Laboratory was negotiating with the Harvard Atomic Data Systems group to have one of its database specialists come to NIST temporarily to implement its server on the network.

• “The panel recommends that final assembly and testing of the electron beam ion trap (EBIT) be accelerated” (p. 149). The assembly and testing of the EBIT are now complete. The project has received fiscal year 1994 competence funding to study the effects of highly charged ions on surfaces and is on the verge of making a new hire. In addition to one NRC postdoctoral research associate, the project has attracted postdoctoral fellows from Hungary, the University of Notre Dame, and Texas A&M University.

• “Because the Gaseous Electronics Conference (GEC) reference reactor program has direct applications to the U.S. semiconductor industry, the panel recommends additional support for the program” (p. 149). The Physics Laboratory provided 1-year funding to allow this project to pursue plasma process control measurements. This project is slated to receive additional funds from the fiscal year 1996 semiconductor initiative.

The Molecular Physics Division uses advanced spectroscopic measurement methods in the time and frequency domain and modern computational techniques to address fundamental and applied molecular problems important to the science and technology infrastructure of the United States.

The main thrusts of the Molecular Physics Division's efforts are advanced instrumentation development applications, new diagnostic methods techniques, and advanced algorithms software for parallel processors. The approach being followed has as its two main goals the development of new instrumentation and techniques that are on the cutting edge of science and the application of these newly developed tools to problems of interest to the U.S. industrial community. The division is focusing on the five broad technology areas of energy and environmental chemistry, semiconductor technology, optical manipulation of matter, catalysis and pharmaceuticals, and chemical process optimization and control. These areas have been chosen because they maximize the overlap of the division's expertise and available equipment and facilities with NIST's mission to assist U.S. industry in its efforts to become more competitive on a global scale.

It is clear that in the next few years developments in the field of solid-state diode laser technology are going to have a substantial impact on all aspects of spectroscopy. New solid-state lasers are rapidly being commercialized that are spectrally pure and have high output power and limited tuning range. Further developments will expand the tunability of these devices, as well as broaden the overall spectral range where the devices operate. These new sources have several desirable characteristics that make them ideal for use in spectroscopic applications. The price of solid-state lasers is already lower than that of conventional lasers, and as new devices are commercialized, the prices should become even lower. The nature of solid-state devices implies that they require only minuscule amounts of electrical power to operate, and they are extremely small in size, all of which makes them desirable for incorporation into many types of spectroscopic instruments for remote sensing and process monitoring applications. Developments in this area will affect at least three of the five focus areas listed above and possibly additional areas over the next few years. As a result, one of the division's major strategies is to seek opportunities to apply solid-state lasers to spectroscopic applications as soon as these devices are available.

Much of the work in energy, environmental chemistry, and chemical process optimization and control involves remote sensing activities. The division's work in these areas is divided into two different thrusts. The first involves the development of sensitive new instrumentation that can be applied to remote sensing applications, and the second is centered on database activities that include obtaining reference spectra of important chemical species, as well as careful linewidth measurements to aid in modeling their pressure-broadened spectra.

Fiscal year 1994 funding for the Molecular Physics Division is estimated at $3.6 million, of which $3.2 million is from STRS. The division currently has 15 technical staff and 7 postdoctoral fellows and was host to 24 guest researchers in fiscal year 1993.

The Molecular Physics Division's choice of focus areas represents a good match between capabilities and skills of the division and areas of real industrial significance. The division has

several leading-edge spectroscopic capabilities that are particularly well suited to providing new insight into industrial issues related to remote sensing, chemical process monitoring and control, catalysis, chemical vapor deposition (CVD), plasma technologies, and semiconductor processes. The panel sees good evidence of outreach to obtain industrial input and connect efforts in program content and industrial collaboration to real industrial problems. The panel believes industrial outreach could be strengthened by having visiting scientists from industry at NIST. Key to making this happen is continued proactive identification of programs of sufficient interest to attract this level of industry commitment.

The panel wishes to stress that the critically reviewed databases maintained by this division are highly valued by industry, as evidenced by the use of these data in industrial models and research. The capability to continually upgrade and critically review molecular data must be maintained.

The Molecular Physics Division does scientific work of the highest caliber as evidenced by its numerous high-quality publications, awards, and first-of-a-kind measurements. Work in high-resolution spectroscopy and molecular dynamics continues to advance the state of the art through development of novel techniques and new instrumentation and acquisition of spectral data on hard-to-measure species. Some specific programs and recent accomplishments are highlighted below.

Femtosecond Broad-band Infrared Spectroscopy. A novel transient infrared spectroscopic dualbeam method incorporating solid-state broad-band infrared down- and up-conversion with 400-femtosecond time resolution is successfully being applied to investigations of ultrafast vibrational energy transfer and photochemistry in condensed-phase systems. This frontier technique uses laser-generated broad-band infrared pulses to record difference spectra of molecules at 4 cm ⁻¹ (wavenumber) resolution over the entire infrared bandwidth and can probe condensed-phase systems at elevated temperature and pressures, thus offering unusual potential to explore industrial catalyst systems under realistic conditions.

Nonlinear Optical Studies of Semiconductor Interfaces. This new project is aimed at developing new measurement methods and scientific understanding useful ultimately for making advanced semiconductor and optoelectronic devices. Work to date includes interface-specific sumfrequency generator studies of the epitaxial interface between Si and CoSi₂ and time-resolved studies of carrier transport at the gallium arsenide (GaAs)/native-oxide/air interface. This work will enable the use of tunable solid-state lasers for in situ monitoring of device growth and performance. This work is being done in collaboration with AT &T and IBM researchers. The panel believes that this is work of very high value that will find application well beyond semiconductor manufacturing.

High-Resolution Microwave Spectroscopy. The High-Resolution Spectroscopy Group is developing Fourier transform microwave (FTMW) techniques for trace gas analysis and makes detailed measurements on molecules of atmospheric and industrial interest. The group currently

plans to produce a compact portable FTMW unit with sensitivity equal to or better than that of current laboratory instruments, in collaboration with American automobile manufacturers. The potential exists for broad application of this instrument in areas such as real-time analysis of exhaust gases, impurity measurements in CVD feedstock, and chemical process monitoring.

Experimental bench marks for leading-edge molecular modeling are much needed. The group plans to do a complete structural analysis of glycine, including hyperfine structure constants and dipole moments. Studies of the HCOOH-NH₃ complex as a possible intermediate in the reaction HCOOH + NH₃ → NH₂CHO + H₂O are an important milestone in this effort, and early results show significant differences from those obtained with theoretical calculations.

Atmospheric Spectroscopy. The unique high-pressure, coolable, multipass absorption cell coupled to a Fourier transform infrared spectrometer is providing high-resolution spectra of molecules of atmospheric interest. This instrument is used to obtain high-resolution data on SO₂ to assist understanding of the impact of large amounts of SO₂ injected into the stratosphere by recent volcanic activity. The capacity to study heavy molecules of atmospheric interest has been enhanced by the group's development of a pulsed molecular-beam slit nozzle coupled to a diode laser. The resultant ability to work at low temperatures greatly simplifies spectra. Molecules of atmospheric interest recently studied include N₂O₃, N₂O₄, and ClONO₂; ClONO₂ is implicated in the chemistry of the Antarctic ozone hole. Data from these studies will be used in balloonborne atmospheric experiments.

Spectra of Transient Molecules. Efforts on vibrational spectra of transient molecules fall into the three areas of evaluated vibrational and electronic spectral data, infrared spectra of molecular ions, and spectra of molecular reaction intermediates in CVD and plasma processing. This work contributes to our understanding of the spectra and chemistry of reactive intermediates. The group's recent work has been summarized in both a monograph and an electronic database.

Laser Spectroscopy of Atmospheric Species. Several unique tunable laser systems have been developed to obtain high-resolution spectra of molecules of atmospheric and industrial interest. Low-temperature and high-resolution capabilities have enabled study of a number of heavy atmospheric species, including several fluorocarbons. This work should be expanded to include all of the fluorocarbons slated for widespread usage, including F-134a (CF₃CFH₂). The success of this work is also evidenced by external funding for measuring collisional lineshapes of atmospheric species. This work has focused on understanding line-mixing interference effects in the spectra of overlapping transitions as well as Dicke-narrowing effects of velocity-changing collisions for atmospheric gases and for HCN, HCCH, and NH₃.

An advanced laser system is being developed in collaboration with a domestic laser manufacturer. Marketed primarily for atmospheric laser-induced detection and ranging (LIDAR), other targeted uses will include photolithography, medicine, and process diagnostics. Key design parameters are a very high energy, pulsed-laser system, narrow bandwidth, and broad tunablity. Current effort is aimed at providing tunability from the vacuum UV to the mid-infrared. The prototype is based on injection seeding a tunable alexandrite laser and generating other wavelengths via nonlinear optics, which allows relatively low cost and small size compared with tunable dye laser systems. Progress over the past 2 years has resulted in the production of a

sodium-LIDAR system for upper atmospheric analysis, which has been marketed and sold internationally.

Laser-based remote optical diagnostics are important tools for assisting industrial compliance with environmental regulations, and the panel suggests this as an area where the Molecular Physics Division could have an impact. Technical problems in frequency conversion and stability must be overcome, and simple, robust measurement methods for accurate wavelength determination are critical. The spectroscopy and environmental line-broadening of target pollutants or process intermediates will form the base input for developing measurement protocols for regulatory agencies and must be determined. Operational safety issues must also be addressed before laser use becomes more widespread. Although the focus is on environmental monitoring, parallel applications to process control should be pursued.

Compressibility Factors for Methane and Water. Highly accurate compressibility factors for CH₄ gas mixtures of varying composition are required by the natural gas and chemical industry for high-pressure gas transfers. The natural gas industry has funded efforts to use ab initio electronic structure calculations to determine an interaction potential for the CH₄-H₂O system, from which compressibility factors can be calculated. Microwave spectra have been used to determine the minimum energy and internal rotation barriers for the CH₄-H₂O dimer and show that the potential minimum has a CH₄-HO hydrogen bond, in disagreement with the calculations.

Molecular Theory Group. The Molecular Theory Group works primarily in the two areas of time-dependent quantum dynamics and optical manipulation of atoms and molecules. Progress has been made in techniques to calculate the effect of interactions between laser-cooled atoms and the response of molecules to very intense laser fields. The intent is to understand how light modifies the motion and dynamics of atoms and molecules. This is leading-edge work in a field with great promise for producing new and interesting techniques for manipulating structure at the atomic level. The time-dependent calculational techniques developed in this work may be adaptable to areas such as catalysis, surface interactions, and the quantum behavior of nanostructures.

The following are the panel's recommendations for the Molecular Physics Division.

• Critically reviewed databases of molecular parameters are an important responsibility of NIST and are much valued by industry. The Molecular Physics Division's capability to extend this effort should be maintained.

• Femtosecond broad-band infrared has unusual potential for the study of reactions of industrial interest. The panel recommends that the Molecular Dynamics Group select a system of industrial interest, preferably in collaboration with industrial partners, for an in-depth mechanistic study. Some candidate catalyst systems for study are Raney-nickel hydrogenations, vanadyl pyrophosphate oxidations, olefin carbonylation, and hydroformylation.

• Development of a portable FTMW instrument has great merit. The High-Resolution Spectroscopy Group should consider bringing an industrial partner interested in manufacturing the device into the development as early as possible.

• Accurate intermolecular potentials are required for a number of industrial applications, including natural gas transport, refrigeration, heat transfer, and gas manufacture. Work on the CH₄-H₂O system is providing useful information. This work should be continued and extended to include compounds of interest to the refrigeration industry.

• Several important industrial models are limited by a continuing need for accurate data and better theory on coupled low-energy rotors. Such theory would be very valuable for improving calculations of partition functions and entropies needed for chemical process models and for modeling of polymer dynamics. The panel recommends that the Molecular Physics Group consider a concerted experimental and theoretical program to address low-energy rotors.

• Laser spectroscopy of atmospheric species provides needed data for atmospheric chemistry and pollution studies. This work should encompass all alternative fluorocarbons slated for widespread usage.

• Laser-based remote optical diagnostics are important tools for assisting industrial compliance with environmental regulations; the division should consider programs to impact this area.

The Radiometric Physics Division develops, improves, and maintains the national standards and measurement techniques for radiation thermometry, spectroradiometry, photometry, and spectrophotometry; disseminates these standards by providing measurement services to customers requiring calibrations of the highest accuracy; and conducts fundamental and applied research to develop the scientific and technical basis for future measurement services.

The Radiometric Physics Division maintains a broad spectrum of fundamental and applied research programs, calibration services, and SRM production to accommodate the technical needs of the radiometric community and provide leadership in identifying future needs. The staff works closely with industry and other government agencies in developing programs to meet specific needs. Additionally, the division staff is active in professional societies and participates in the activities of CORM and CIE. These organizations provide the division insight in identifying the emerging needs of U.S. industry to support the growth of quality manufacturing efforts.

The division is organized into four groups and operates under a project structure with collaborations across group lines. Each project has an assigned group leader who is responsible for planning and accomplishing the technical objectives of the project. The project teams in the division interact and work jointly on various tasks, sharing resources to achieve common goals. The project structure is fluid to allow for redirection of resources to accomplish newly identified program goals.

Fiscal year 1994 funding for the Radiometric Physics Division is estimated at $6.0 million, of which $2.5 million is from STRS. The division currently has 31 technical staff and was host to 9 guest researchers in fiscal year 1993.

The implementation of the project concept with assigned group leaders has allowed the Radiometric Physics Division to manage its diverse programs effectively. This concept is also being applied to a joint project with the Electron and Optical Physics Division.

The panel believes that the present strategic plan is on track in terms of technical programs, goals, and facilities. The method of funding these programs, however, is of concern to the panel. The Radiometric Physics Division is at high risk because of the inordinate size of OA funding, which accounts for 62 percent of the budget for fiscal year 1994. In previous years, this funding has been used to develop and maintain such programs as the Low-Background Infrared Facility, the Imaging Radiometry project, and the High-Accuracy Cryogenic Radiometer (HACR) project. Based on repeated requests from U.S. industry, the division has linked the radiometric and photometric scales to the HACR to improve the measurement uncertainty of these scales. The HACR has been largely funded by OA money. The facility is up and running but lacks base funding to pursue long-term needs expressed by U.S. industry through groups such as CORM. The panel predicts a negative impact on U.S. industries if stable long-term funding is not found for the HACR, the Spectrophotometry Group, and projects designed to improve the measurement uncertainty of radiometric, photometric, and spectrophotometric standards and measurement services.

The panel was impressed with the Radiometric Physics Division's knowledge and ability to handle a wide range of technical projects and serve such a large and diverse community of customers. Considerable progress has been made in the establishment of a quality system that will meet the requirements of the International Organization for Standardization (ISO) 9000 series and ISO Guide 25 documents. The panel is very encouraged to see the Radiometric Physics Division take the lead in this area. The rebuilding of the spectrophotometry laboratory with the acquisition of new equipment and personnel is also a very positive step. The balance between research and

development and customer calibration services is nearly proper, and continued coordination with customers should assure that this balance is achieved and maintained. The division has worked hard at this goal and is to be commended for its progress. The panel was pleased that workshops with and for industry are being pursued. The May 1994 “Air Ultraviolet” workshop is a good example. An impressive number of papers have been published since the fiscal year 1993 asessment from all three groups of the division.

Detector Metrology Group. The HACR project is designed to supply measurements to support the division's radiometric scales and provide traceability for optical power measurements to the watt, an SI unit. The project is nearing completion of its long-term goal of automation and has begun a scale realization that is to be completed by mid-1994. The new tunnel trap detectors have developed alignment problems, which have forced use of older trap detectors. The project will push into the infrared spectral region with a carbon dioxide laser operating at 10.6 µm. A paper on the HACR instrumentation was in press at the time of this assessment.

The division is again providing luminous intensity, luminous flux, and luminance measurements for incandescent sources ranging from 0.24 to 1000 W. The Photometry Section has also reevaluated and reissued opal glass standards for customers to develop a luminance scale using irradiance standards and the opal glass and is providing calibration services for photometers and colorimeters. The group is involved in many new projects, including the development of a new scale for luminous and spectral flux based on a large integrating sphere and an external source.

The Bidirectional Reflectance Distribution Function project has made a number of advances in the last year. Construction, alignment, and testing of the new goniometer are complete. Standard reference materials for scatter made from black glass are now being produced with a BRDF from 10⁻² to 10⁻⁶.

The Detector Metrology Group has built four new germanium (Ge) radiometers for detector calibration services and is currently testing a new cryogenic bolometer for use in measuring the relative spectral response in the UV and infrared scale realizations. In detector applications, a new modular radiometer has been designed with Si and Ge photodiodes. A cryogenic bolometer was designed and tested, and new large-area indium GaAs photodiodes for radiometric applications were investigated.

The division has established a team to begin the implementation of ISO Guide 25 to assure the quality of calibrations and testing services. The team has put together a plan to develop a quality system and has established the positions of technical manager and quality manager. A new uniform test format, forms, and procedures are being developed. The team has also received external training and has visited a U.S. industrial facility that operates a fully accredited quality system. The division has been very proactive in this area and is one of the leaders at NIST in the implementation of ISO Guide 25. The panel encourages the team, division, and laboratory to promote and fund this effort from the top down.

Infrared Radiometry Group. The Infrared Radiometry Group is making steady progress with implementation of new technology and highly focused project orientation.

Outstanding progress has been made in the Low-Background Infrared Radiation Facility. A new cryogenic chamber has been designed and built to allow spectral calibrations on a routine basis. The two cryogenic systems are state of the art and should provide critical program support

for the Department of Defense, the National Aeronautics and Space Administration, and related projects.

The Infrared Detector Comparator Facility is expected to provide detector responsivity calibrations over the 20- to 30-µm spectral range. Inclusion of an integrating prism grating monochrometer, together with a cryogenic bolometer traceable to the absolute cryogenic radiometer, will allow detailed responsivity measurements. A new measuring system has been designed to allow infrared optical properties of materials measurements at cryogenic temperatures. This new system is expected to allow for measurements over the 2- to 10-µm range.

A unique hemiellipsoidal apparatus has been assembled for diffuse reflectance measurements. To date, diffuse reflectance at 10.6 µ m has been measured for plasma and regular gold coatings. This project has many applications in material research. New SRMs have been developed for use in the mid-infrared wavelength range.

Progress continues in correlated photon source work. This technology allows photon counting without the use of any additional external standards, which will be useful for quantum efficiency measurements of photomultipliers and characterization of materials that require photon counting sensitivity. Two systems are planned, one operating in the visible and the other in the infrared. Comparisons will be made with the HACR and existing calorimetric methods to determine if this technique can lead to an intrinsic standard.

Thermal Radiometry Group. One of the major accomplishments of the Absolute Detector Based Radiometry project is the development of six detector packages to cover the spectral region from 400 to 900 nm. In addition, the high-temperature blackbody (up to 2800 K) has been tested for stability and uniformity. The project has experienced some setbacks but is now moving ahead, and the panel notes the importance of this project.

The division has added a new full-time staff person to the high-accuracy UV through visible to near infrared (UV-VIS-NIR) spectrophotometry project. The goal of this project is to upgrade the present high-accuracy spectrophotometer and to develop a program in optical properties of materials. To date, a clean room has been acquired, and plans have been formulated to upgrade the present monochromator. Spectrophotometry has needed many upgrades, and this project represents a positive first step toward a world-class spectrophotometry facility. Optical properties of materials will be studied using this upgraded instrument and other spectrophotometers in the division.

A new NIST water bath area blackbody has been developed as part of the Blackbody Development project. This new blackbody operates between 5° and 95° C and is more accurate, stable, and uniform. In addition to the water bath blackbody, a higher-temperature oil bath blackbody operating from 60° to 200° C and a cesium pressure-controlled heat pipe (400° to 1100° C) have been designed and operated.

In Measurement Services, the Facility for Automated Spectroradiometric Calibrations (FASCAL) has been used to characterize a modified free electron laser (FEL) lamp developed by Osram Sylvania. This effort was very successful, and the section is now issuing 1000-W FEL lamps with spectral irradiance data on a routine basis. The new lamps are not completely trouble free; evidence of spectral lines and absorption bands have reappeared in these quartz halogen lamps. Future plans call for the update of FASCAL procedures to conform to ISO requirements.

The division is responsible for the realization of the international temperature scale (ITS-90) above the freezing point of silver. U.S. industry and government laboratories use the silver freezing point as a reference to scale all the way up to 3000° C with perhaps only the gold and copper points in between. Plans for this realization call for the use of SURF III. This promises to be of extreme interest and value to U.S. industry, and the panel is pleased with the approach chosen.

The following are the panel's recommendations for the Radiometric Physics Division.

• Laboratory management should seek to stabilize funding for the Radiometric Physics Division. The division's large proportion of OA funding leaves important projects in continual jeopardy and can distract the division from its own mission.

• Industry, through the American Society for Testing and Materials, CORM, the National Conference of Standards Laboratories, and other organizations, has repeatedly provided detailed input on its needs in optical radiation measurement. Laboratory management and the division must work to meet these needs in photometry, radiometry, and spectrophotometry. Specifically, the division must maintain and improve HACR, develop robust transfer standards, and achieve compliance with ISO Guide 25 for all calibration services.

Given below are some of the panel's fiscal year 1993 recommendations for the Radiometric Physics Division (quoted from the fiscal year 1993 assessment), with the division 's responses.

• “Because the ambient background infrared facility (ABIR) has several challenges to meet, the panel recommends that the Radiometric Physics Division prepare a detailed time line to track the various facets of the planned improvements” (p. 149). Following the panel's suggestion, the group prepared a detailed time line in summer 1993 and incorporated milestones into individual performance plans as appropriate. Progress is now on schedule.

• “The panel recommends that (1) a well-thought-out plan and time line be developed for the Optical Properties of Materials Program on the basis of customer input, (2) two additional full-time professionals be hired and adequate Scientific and Technical Research and Services (STRS) funding be secured for this program, and (3) a high priority be placed on implementing International Organization for Standardization (ISO) Guide 25 policies” (p. 149). A preliminary plan has been formulated and distributed to the panel and other agency sponsors of the spectrophotometry program. Additional funding needs to be found and dedicated to the long-term efforts in spectrophotometry and a modern research and development program formulated and pursued. This will be a prime goal of a cooperative effort by the division as a whole over the

next few years. The division has embarked on an effort to establish ISO Guide 25 compliance in all of its calibration and measurement services laboratories.

• “The panel recommends that the Radiometric Physics Division examine all of the scales to be integrated with the high accuracy cryogenic radiometer (HACR) and prepare a master plan to address the tasks required to achieve this objective, associated funding required, and the proposed time line for completion” (p. 149). The Detector Metrology Group is developing an overall plan and sets of procedures to implement the high-accuracy capability of the HACR in the division 's measurement chains. Additional funding has been obtained for this effort. A plan to have the spectral radiance and irradiance scales on an absolute detector base has been formulated. The plan calls for first implementation in fiscal year 1994 with details such as the stability of the variable-temperature blackbody to be addressed in fiscal year 1995.

• “Several papers and presentations have been prepared since the fiscal year 1992 assessment; however, the panel recommends that dissemination of the technologies being developed within HACR be intensified” (p. 149). New special publication 250 (SP 250) documents describing the progress in using the HACR in measurement efforts were completed in fiscal year 1993. An outline of one on spectral response has been completed and writing tasks assigned. The updated SP 250 for photometry will draw heavily on the candela paper (“The Detector-Based Candela Scale and Related Photometric Calibration Procedures at NIST,” Illumination Engineering Society of North America, in press at time of assessment) and will include descriptions of the new measurement services for luminance, illuminance, and luminous flux. Papers were presented at the Illumination Engineering Society annual meeting and at the Society of Photo-optical Instrumentation Engineers meetings. An additional manuscript describing new luminous flux measurements is being submitted to an appropriate scientific journal. The group expects to have about three contributions to the NEWRAD 94 conference in Berlin in the fall of 1994.

The Quantum Metrology Division advances x-ray technology and metrology in support of industrial applications, medical radiology, materials research, and space observations; contributes to the extension and refinement of the electromagnetic scale by measurements linking standards in the visible with others in the x-ray and gamma-ray regions; and maintains formal industrial collaborations as required for the dissemination of NIST inventions, support of Advanced Technology Program (ATP) awardees, and other applications of x-ray technologies.

Given the small size of the Quantum Metrology Division (eight full-time, permanent scientists and about six visiting scientists), it is not organized into groups. Nevertheless, the division is involved in a large number of projects and facilities, including a beamline at the NSLS at the Brookhaven National Laboratory and gamma-ray facilities at the Institute Laue Langevin

(ILL) in Grenoble, France. The highest priority in the future will be given to technology development and applications. One application that has already been productive involves applying diffraction spectrometry to mammographic quality control via full spectral profiling and end-point x-ray energy determination. A new technological area has recently opened through unexpected synergisms between existing division programs and the needs of the Advanced Photon Source (APS) at the Argonne National Laboratory. These opportunities are being aggressively pursued to supplement the current staff with personnel from Argonne and to use the division's beamline at the Brookhaven synchrotron as a test bench for needed developmental work for the APS. In connection with NIST's responsibilities in base standards, the next highest priority of the division will be work on the realization of a nonartifact kilogram using the x-ray/crystal density approach.

Fiscal year 1994 funding for the Quantum Metrology Division is estimated at $2.2 million, of which $1.7 million is from STRS. The division currently has seven technical staff and one postdoctoral fellow and hosted eight guest researchers in fiscal year 1993.

The technical expertise in the Quantum Metrology Division in x-ray physics and technology is a national resource. In concert with the new and extended missions of NIST in serving U.S. industry, the strategy of applying this expertise to selected industrial and medical problems is appropriate. Finding additional means and users to support the division's beamline at NSLS and the gamma-ray spectrometers at ILL is important and responsible, since these facilities represent considerable investments and are unique in the international scientific infrastructure.

Multilayers. Ultrathin multilayers constructed from certain vacuum-deposited materials provide technological advantages over other materials found in nature. Various multilayer structures have been fabricated in the division, including carbon-nickel structures. The agreement between theoretical model calculations and reflectometry measurements at SURF II is impressive. The combination of production and characterization along with figure metrology and atomic force microscopy available at NIST permits efficient pursuit of these endeavors and rapid development of multilayer applications for end-product x-ray users.

X-ray Calibration Services. The division provides special calibration services for industrial x-ray optical components, spaceflight instrumentation, scientific spectroscopy, and diagnostic radiation quality. Current work includes evaluating polycapillary components of an x-ray collimator for proximity lithography, funded partly by the Advanced Research Projects Agency and the ATP, and led by AT&T. It involves the prime product of X-ray Optical Systems, Inc., with which the division has a CRADA.

Spectrometry for Mammography. The development of a Laue-case diffraction spectrometer for high-voltage and spectral determination has been granted patent protection. Interest in this device for mammographic x-ray sources has been widespread, since it allows direct measurement of the high voltage and spectral emission of the source, which are both extremely important in dose calculations. For the flat silicon transmission crystal used in the first designs, the spectrometric resolution obtained in the image plane is limited by the focal spot size. For many units in clinical work, the spot size is of the order of 300 µm. This problem has been overcome recently with a device that uses a carefully bent crystal to achieve focusing. Proposals with the Army Breast Cancer Research Fund and the National Cancer Institute for substantial funding are pending. A collaboration with the Georgetown University Medical Center and the company being licensed for commercialization has been established. This program is an example of how rather sophisticated x-ray physics can affect an important area of technology and medical treatment.

Spectra of Highly Ionized Atoms. Recently, the division has used a variable radius focusing crystal spectrometer to make the first measurements at the newly commissioned EBIT of the spectra of neon-like and sodium-like barium. Because the trapped ions are cold, their spectra are not subject to Doppler broadening, and the full-resolution capability of the crystal spectrometer is utilized. The EBIT facility is operated by the Atomic Physics Division, and measurements were done in collaboration with a group from the Naval Research Laboratory. Spectra from isolated atoms and ions provide the building block for understanding clusters of condensed atoms, atoms on surfaces, and atoms in the solid state, the basis of all materials science. Information on highly ionized atoms is also essential for thermonuclear energy research.

X-25A Beamline at NSLS and Gamma-ray Spectrometers at ILL. As mentioned earlier, these facilities were constructed over many years by personnel and funding from the division. They contribute a unique capability to the international scientific community. Various prizes in physics have been awarded to users of these facilities. The ILL reactor is the best in the world and has provided a special opportunity to carry out high-resolution gamma-ray spectroscopy. The ILL reactor has been shut down for 3 years to rebuild its pressure vessel and internal structure and was scheduled to start up again during the summer of 1994. NIST personnel will reinstall the gamma-ray instruments. The question of who should maintain these facilities and pay for the costs of operation is a significant challenge to the division chief and a responsibility to the worldwide scientific infrastructure.

The following is the panel's recommendation for the Quantum Metrology Division.

• The panel recommends that a group structure be developed for the Quantum Metrology Division, with some autonomy given to the group leaders. Despite its small size, the division's special technical expertise in x-ray technology is unparalleled in the world and needs to be more available to U.S. industry. A clear group structure would assist in this aim. The panel suggests groups in fundamental x-ray and gamma-ray research and in technological applications of x rays. A third group in fundamental metrology for development of a nonartifactual mass standard might also be appropriate.

The Ionizing Radiation Division provides primary national standards, dosimetry methods, measurement services, and basic data for application of ionizing radiation (x rays, gamma rays, electrons, neutrons, energetic charged particles, and radioactivity) for radiation protection of workers and the general public, radiation therapy and diagnosis, nuclear medicine, radiography, industrial radiation processing, nuclear electric power, national defense, space science, and environmental protection; conducts theoretical and experimental research on weak interaction physics and fundamental quantum physics and on the fundamental physical interactions of ionizing radiation with matter; develops an understanding of basic mechanisms in radiation particle tracks and associated stochastic processes in the absorption of radiation by chemical and biological systems on the micrometer and nanometer scales, which will lead to predictions of end-points for radiation-induced effects; develops improved methods for radiation measurement, dosimetry, and two- and three-dimensional mapping of radiation dose distributions; develops improved primary and transfer radiation standards, and produces highly accurate standard reference data for ionizing radiation and radioactive materials; provides standard reference materials, calibrations, and measurement quality assurance services to users such as hospitals, industry, states, and other federal agencies; develops measurement methods and technology for use by the radiation processing industry, health care industry, nuclear electric power industry, environmental technology, and radiation-using industrial applications; and develops and operates well-characterized sources and beams of electrons, photons, and neutrons for primary radiation standards, calibrations, research on radiation interactions, and development of measurement methods.

The Ionizing Radiation Division's strategic plan for 1994 is directed to increasing technical competence in its areas of preeminence, radionuclide and environmental radioactivity standards, neutron measurements and standards, dosimetry of ionizing radiation, and radiation data centers. The first competence rests in the Radioactivity Group, the second in the Neutron Interactions and Dosimetry Group, and the last two in the Radiation Interactions and Dosimetry Group. The division strategic plan emphasizes traditional strengths, namely, service to industry, radiation and radionuclide metrology, fundamental neutron measurements, and work with university and industry collaborators to pursue new opportunities.

The Ionizing Radiation Division's fiscal year 1994 funding is estimated to be $7.8 million, of which $3.8 million is from STRS. The division currently has 41 technical staff and 2 postdoctoral fellows and hosted 29 guest researchers in fiscal year 1993.

The panel's consensus is that the Ionizing Radiation Division's stated strategy is not sufficiently forward looking. It fails to integrate the major changes in funding and emphasis on industrial relevance that is current at NIST. The strategy as stated could have been written anytime in the past 5 years. The panel suggests that the division develop a strategy that reflects a vision of the role the division can play in carrying out the externally envisioned role of NIST and its programs. Examples of appropriate strategic statements would be, “The division will appoint an outside task group to help it develop and prioritize how it can optimally contribute its expertise and develop new programs in the area of medical care,” or “The division will seek out at least five new industrial partnerships,” or “The division will develop an administrative structure that seeks to delineate unique technical responsibilities, eliminates duplication, appropriately manages scientific staff, improves dissemination of important technical information to users, and prioritizes resources.”

The division has a wide customer base for its services and expertise. These span the gamut of industrial (radiation processing, sterilization, radiopharmaceutical), infrastructure (nuclear power), governmental (environmental radioactivity, defense, radiation protection of workers), and medical (radiation therapy dosimetry/dose specification, mammography techniques/dose specification/quality assurance) customers. The panel observes that the division is very proactive in the areas of industrial consultations, as well as of service and advice to professional societies and standards groups. The division also has a good record of participating in CRADAs and the ATP and sees increased participation in the future as an opportunity for furthering its contributions to industry. In view of its areas of expertise, the division is poised to make significant contributions in the areas of medicine and the environment.

The panel finds that the technical programs of the division are of very high quality, with a number of exceptional scientists participating. Many of the programs appear to be appropriate to the mission and technologically are state of the art. However, some key programs rely on contract employees, including a large number of retired scientists, raising questions of continuity and timeliness. A number of new hires have been made in the last few years, but the division appears to be weak in permanent mid-career personnel.

Radiation Interactions and Dosimetry Group. The panel sees that this group has some duplication of mission with the Office of Radiation Measurement (e.g., dissemination and quality assurance of radiation dosimetry standards). The Ionizing Radiation Division should more clearly define its mission and primary and exclusive responsibility for certain objectives (e.g., liaison with international standards committees on environmental activity assessment, brachytherapy source specification, mammography dose determination, and so on).

It is the panel's view that the industrial high-dose dosimetry program is a unique and valuable national resource, since it provides standardization and measurement technique leadership in the important area of industrial sterilization and other high-dose techniques. A more formal collaborative effort with industrial users in a program analogous to programs with the radiopharmaceutical and nuclear power industries would strengthen the NIST program, provide

needed support for absorbed dose rates in high-dose irradiations, and promote technical exchange with industry, as well as suggest and provide a forum for developing consensus about competing technology.

The electron paramagnetic resonance alanine industrial dosimetry effort is, in the view of the panel, an exciting measurement technique that needs to have final questions (shelf life, cost) answered and be made available to the industrial community at the earliest possible date. This new development will be of great use to the technical, industrial, and medical communities. This work is being carried out under CRADAs with two different firms.

The panel suggests increased communications between end-users and NIST personnel. Even though the group hosts a wide variety of visiting scientists each year, it is not clear that NIST personnel can spend time at appropriate end-users' facilities. Perhaps a minisabbatical (2 to 4 weeks) program could be established. The group, division, and laboratory should also support and nurture interactions with the Council for Ionizing Radiation Measurement Standards (CIRMS) to define and evaluate programs more clearly.

Newer efforts in medical dosimetry include the development of air-kerma standards for mammographic x-ray beam qualities and commissioning of a medical-industrial radiation facility (MIRF). Medical applications will continue to be an important area for this group. It is the panel 's view that a mid-career certified medical physicist could provide enhanced internal peer review and technical direction, plus provide a liaison with potential users of MIRF and act as a NIST representative to appropriate scientific societies, e.g., the American Association of Physicists in Medicine.

The radiation interactions program is supported by a theory section that depends in large measure on work by contract employees (retired staff). It is the panel's view that this is not satisfactory over the long term. The group needs to determine the areas of expertise for which it wishes to claim preeminence and respond with appropriate support. Division management needs to work towards ensuring a synergy between this group and other experimental programs.

Some of the group's key efforts in the area of medical dosimetry (absolute calorimetric dosimetry, air-kerma determinations of medical radionuclides) are, in large part, the result of efforts of recent retirees. The panel suggests that the group develop a strategy to enhance and continue this work, which continues to be important to the medical care industry.

The panel finds that the Radiation Interactions and Dosimetry Group has nationally significant contributions to make to the areas of industrial and medical dosimetry and that these represent appropriate opportunity areas for the division, laboratory, and NIST. Many of the personnel in the group are of national note, and the group published 42 papers last year. Reliance on contracted retirees in areas of theory and medical dosimetry as well as the apparent lack of mid-career personnel will hamper the group as it tries to successfully respond to opportunities over the next few years. Division management needs to define clear short-term and long-term goals, put in place a participatory structure to ensure maximal utilization of limited resources, and be creative in responding to mid-career personnel needs.

Radioactivity Group. Management may want to better define the boundaries between the Office of Radiation Measurements and the Radioactivity Group. A more formal mechanism for setting priorities between the two groups is needed. The list of projects for fiscal year 1995 appears to be large for the current size of the group.

There has been a tremendous improvement in the organization and morale of this group compared with that at the panel's 1993 assessment. A group leader has been appointed after an extensive national search. The new leader has an excellent record of research in all areas of the group's goals and organization. Appointment of senior scientists to lead projects will assure the identity and accountability of each program. Focusing the group's efforts on nuclear medicine, the environment, and basic calibrations reflects the country's current needs. It will be important to review the scientific progress of these three programs at the next review period.

The panel is concerned that the large dependence on outside money is detrimental to this group. In addition, interagency discussions at the highest level must prevent costly duplication of NIST capabilities by other agencies, in particular the Department of Energy.

The NIST-Nuclear Energy Institute radiopharmaceutical program is a good example of NIST-industry collaboration and should be emulated by the appropriate environmental industries. The expansion of nuclear medicine into bone palliation therapy and the radioactive cleanup program will demand further expansion of this program. The panel thinks that a more aggressive program to identify new areas of research through CIRMS needs to be instituted. In addition, senior investigators may want to institute regular visits to customers in the fields of nuclear medicine and environmental safety to experience their needs first hand.

Neutron Interactions and Dosimetry Group. The Neutron Interactions and Dosimetry Group's area of research and expertise ranges from very practical advice to and interaction with the nuclear power industry to fundamental research in neutron interferometry. The accomplishments of the group are world class.

The neutron interferometer research station has become operational since the fiscal year 1993 assessment. Advanced thermal and acoustic control systems and vibrational isolation and positional stability control systems have been developed and are now operational, making the NIST neutron interferometer facility the best in the world. Time-dependent phase variations of interference pattern observed at NIST are an order-of-magnitude better than those observed elsewhere with the same crystal interferometer. Applications to a variety of phenomena should be forthcoming by the end of fiscal year 1994.

A new determination of the neutron lifetime, a fundamental quantity of great importance, is being attempted to improve accuracy and reduce experimental uncertainty. Since spring 1993, over 3 million neutron decay events were observed and recorded. Publication of improved values is expected by the end of fiscal year 1994.

Rapid progress is being made toward the production of spin-polarized neutrons, obtained by means of a ³He filter. Such a filter is based on spin exchange between 3He and optically pumped Rb and will be quite valuable at pulsed neutron sources.

Office of Radiation Measurement. It is the panel's unanimous concern that the scientific efforts being performed under the auspices of the Office of Radiation Measurement (ORM) overlap the work performed by other groups within the division without appropriate coordination and peer review. The division should consider placing these efforts within the other groups. Support and appropriate reporting structure need to be formulated by the division chief. It is the panel's impression that the Office of Radiation Measurement is an important element in fulfilling the potential needs of the industrial, technical, medical, and environmental communities in the areas of radiation measurement quality assurance and standardization, but the division needs to put in

place programs aimed at ascertaining the extent of this need in order to properly formulate its role and staffing needs.

The following are the panel's recommendations for the Ionizing Radiation Division.

• The division should increase mid-career permanent scientific staff or plan strategically for continuation of key programs currently depending on contract retired employees, or both.

• The exact role and functioning of the Office of Radiation Management needs to be resolved, especially questions relating to the location and reporting of its current scientific staff.

• Industrially driven high-dose dosimetry programs should be given increased emphasis; future efforts in medical radiation programs would be enhanced by a staff medical radiation physicist.

• The division should perform a top-to-bottom survey of programs, evaluating them in terms of NIST and division mission statements and consolidating, rearranging, and eliminating as appropriate.

• Strategies appropriate to the goals of the division should be developed, with the entire scientific staff involved in major decisions about technical direction and priorities.

• General program areas are too broad to be carried out by the existing and shrinking permanent scientific staff. The Ionizing Radiation Division must define its programs more specifically. For example, environmental monitoring of radioactivity is a large area, whereas assaying nanocurie levels of mid-Z radionuclides in soil is better defined.

Given below are some of the panel's fiscal year 1993 recommendations for the Ionizing Radiation Division (quoted from the fiscal year 1993 assessment), with the division 's responses.

• “The Committee on Interagency Radiation Research and Policy Coordination should help develop priorities for the Office of Radiation Measurement 's services” (p. 150). The ORM has been actively pursuing new avenues in the areas of dosimetry (e.g., mammography, industrial high-dose accreditation; proficiency testing for neutron dosimetry and extremity dosimetry, American National Standards Institute [ANSI] N13.30 standard on Performance Criteria for Radiobioassay). Likewise, ORM has been pursuing avenues related to environmental cleanup (e.g., ANSI N42.2 standard on Measurement Quality Assurance [MQA] for Radioassay Laboratories, Workshop on MQA for Ionization Radiation, Conference on Metrology for Environmental Management, Briefing for EM-563, R/D on leachability of Sr-90 species from

SRM 4353). The ORM has drafted a strategic plan, updated yearly, that positions dosimetry and radioactivity MQA outreach efforts as high-priority programs.

• “In its fiscal year 1992 assessment the panel recommended that a senior scientist be sought to lead standards activities in the Radioactivity Group. It reiterates that recommendation here” (p. 150). Following the recommendations of an ad hoc search committee, an appointment has been made to lead the work of the Radioactivity Group.

• “The panel recommends an integration of the Office of Radiation Measurement and the Radioactivity Group in view of their overlapping missions. The identities of the two groups could be preserved under a new ‘radiation standards group' ” (p. 150). Laboratory management is aware that a merger of the two groups would have advantages but feels that, with the imminent retirement of the division chief, any reorganization should be the prerogative of his successor.

• “In view of the Ionizing Radiation Division chief's plan to retire in June 1994, the panel recommends that a nationwide search begin immediately to recruit a senior scientist of international reputation as a replacement” (p. 150). An ad hoc committee has recently completed a nationwide search, and a new chief has been appointed.

The mission of the Time and Frequency Division is to produce and maintain the U.S. standards of time and frequency and coordinate them internationally; develop laser-based length standards in support of NIST programs in length metrology and optical metrology; provide time and frequency services for users in the United States; and perform research and development on new standards, measurement methods, and dissemination techniques.

The division has identified four industrial needs to which it will respond: efficient access to high-accuracy frequency and time signals, spectral purity calibrations and a more stable time scale, more accurate and simpler atomic frequency standards, and accurate optical-frequency and length measurements. The four program areas of broadcast services, calibrations and operations, atomic frequency standards, and optical frequency metrology were chosen on the basis of customer demand, projected demands for accuracy based on historical trends, and perceived importance to NIST's metrology mission. These programs will evolve in 3 to 5 years toward satellite systems and optical fiber telecommunications and greater automation; toward practical international standards available in real time; toward standards based on optical manipulation of states and motions of atoms; and toward integrated laser systems that are cheap, tunable, and highly reliable.

Fiscal year 1994 funding for the Time and Frequency Division is estimated at $7.1 million, of which $5.6 million is from STRS. The division currently has 27 technical staff and 8 postdoctoral fellows and hosted 25 guest researchers in fiscal year 1993.

The Time and Frequency Division's strategy, as currently implemented, seems appropriate to the available resources. Resources are definitely limited, and there is a realistic outlook on what can be done with existing personnel and money. With more program support, the division could grow in importance to NIST and maintain its high level of performance and impressiveness.

The division's excellent management and very high levels of scientific and technical strength make it possible to attract more first-rate scientists and technical support to engage in new avenues of research and development and thus broaden its work in supporting U.S. metrology. The panel would welcome real growth in the Time and Frequency Division.

NIST-7 is now a world-class frequency standard with frequency accuracy of about 1 part in 10¹⁴. Further improvement by a factor of 2 or 3 seems possible. Two supporting activities are under way that will aid in attaining and maintaining this level of accuracy. The first is the use of the highly precise trapped ion frequency discriminator, developed for establishing a long-term (months/years) frequency reference for NIST-7. The other is the use of the cesium fountain standard, under development in the Atomic Physics Division, as a workstation for investigating cesium beam velocity distribution effects, such as Doppler broadening, Cs-Cs atomic collisions, and other possible systematic frequency shifts in NIST-7. As this work proceeds, it should be possible to evaluate the cesium fountain as a possible future primary frequency standard for NIST.

Efforts in implementing a frequency discriminator of extremely high precision using the trapped and cooled ion technique are progressing well. A numerical relationship between the frequency of NIST-7 and that of the resonance of a trapped array of ions will help establish long-term credibility in the assessment of systematic frequency offsets in the NIST-7 frequency standard.

Work on an advanced version of the cesium atomic fountain clock in the Atomic Physics Division is in progress, and NIST should soon be able to catch up with, and overtake, the European group that currently has a cesium atomic fountain clock in operation. The high level of NIST experience and expertise in this technique should result in a very good understanding of the effects of velocity distribution and collisions in NIST-7 and enable even more precise evaluations of systematic frequency shifts inherent to its design as an optically pumped room-temperature atomic beam standard. The panel expects that NIST-7 will operate in a highly routine, even automated, manner to provide an effective operational basis for defining the U.S. primary frequency and time scales.

NIST-7 is advancing well, and good progress can be anticipated with the existing personnel. The same level of effort should continue to be applied to this standard in the expectation of achieving the world's best manifestation of the cesium frequency for defining the second.

In accordance with the SI definition of length based on the velocity of light, the NIST primary length standard will be based on the NIST frequency standard. This will be done by establishing a coherent frequency relationship between a beam of light and the cesium hyperfine frequency by which the second of time is defined. For implementing this measurement process, a frequency multiplier chain from microwave to optical frequencies is required. This link will provide an optical reference frequency with which a highly stable laser can be compared. There are two phases for this effort. The first is to generate the light beam, probably by establishing a phase-locked frequency link from NIST-7 to an He-Ne iodine-stabilized laser. This light source will then be used to calibrate various secondary standards. The development of secondary standards will be supported by the division's highly successful laser diode program. Very productive work on lasers continues at a good pace. Work on the frequency multiplication chain to optical frequencies will begin in fiscal year 1995. This effort is vital to the establishment of a working unit of length and is worthy of additional resources so that activity in the United States will not fall behind similar European activity.

Because length is a fundamental unit of measurement and is vital to U.S. industry, disseminating accurate length information and establishing a facility for calibration of secondary length standards should also be given a high priority. Research in the division on line-narrowed diode lasers as well as other work is leading to the development of laser-based secondary length standards. Large numbers of these will be required to support U.S. industry, and the Time and Frequency Division will likely play a strong role in this important work. Additional resources would accelerate this process.

Time and frequency services are being adjusted to suit national requirements, and these services are being efficiently delivered. An important part of this work is the successful development of calibration equipment to evaluate the spectral purity of oscillators and the nature of their frequency instabilities. NIST is a world leader in this work and is uniquely capable of fulfilling a very pressing need for time synchronization in the communications industry, both in the United States and worldwide. The high level of technical progress in work related to the development of standards for spectral purity measurements is an important part of the development of the frequency multiplication chain to optical frequencies needed for defining length. This is a good example of the synergy in the strategic planning of the Time and Frequency Division. The issues of quantifying spectral purity and the accuracy of measurement equipment have been long neglected in the frequency and time community, and NIST is the world leader in such work.

High-precision time transfer and time synchronization for high-speed telecommunications are of growing importance to U.S. industry and for U.S. navigation systems. The Time and Frequency Division is at the forefront of this technology.

The following are the panel's recommendations for the Time and Frequency Division.

• Progress on the length standard should be accelerated, if this can be done without expense to other activity now under way in the Physics Laboratory.

• A clearer exposition of the delegation of authority and responsibility within NIST for the standard of length should be developed, with a plan for the eventual implementation of the primary standard and for the U.S. facility for calibrating secondary standards of length from the primary frequency standard.

• The division should consider a cryogenic capability for metrological experiments at low temperature, but not at the expense of other programs.

Given below are the panel's fiscal year 1993 recommendations for the Time and Frequency Division (quoted from the fiscal year 1993 assessment), with the division 's responses.

• “The panel recommends that the Time and Frequency Division invest in the personnel and equipment necessary to develop precommercial cryogenic oscillators” (p. 150). The division is staying abreast of the field and monitoring its progress but does not feel it can initiate a new project in this area without additional staff and resources.

• “The panel recommends that NIST formalize, in some useful way, a new definition of the meter in terms of the velocity of light” (p. 151). In response to the panel's recommendation, NIST management has assigned the division responsibility for realizing optical frequency (wavelength) standards in the form of atom-stabilized lasers and has provided base funding for this effort. The division will work closely with the Precision Engineering Division of the Manufacturing Engineering Laboratory to assure that its developments can have an impact on practical length metrology.

The following biennial assessment of the fiscal year 1994 activities of the Joint Institute for Laboratory Astrophysics is based on a site visit and meeting of the subpanel on January 27 and 28, 1994, and on the annual report of the Quantum Physics Division of the Physics Laboratory.

Members of the subpanel for the Joint Institute for Laboratory Astrophysics included David E. Pritchard, Massachusetts Institute of Technology, Chair; J. Norman Bardsley, Lawrence Livermore National Laboratory; Peter J. Chantry, Westinghouse Science and Technology Center; F. Fleming Crim, University of Wisconsin; Peter E. Glaser, Arthur D. Little, Inc.; Daniel R. Grischkowsky, Oklahoma State University; James R. Houck, Cornell University; Christopher F. McKee, University of California, Berkeley; and David Wilkinson, Princeton University.

The Joint Institute for Laboratory Astrophysics (JILA) was established in 1962 with the adoption of a memorandum of understanding between the University of Colorado and the National Bureau of Standards (NBS), now the National Institute of Standards and Technology (NIST). Each participating institution provides JILA with permanent positions to be filled by senior scientists. Although they share responsibility for JILA's success, NIST and the University of Colorado each has full operational responsibility for its own employees at JILA. Decisions regarding tenure or career appointment reside in the parent body, not in JILA.

The NIST component of JILA is primarily in the Quantum Physics Division (QPD) of the Physics Laboratory, except for one senior scientist from the Time and Frequency Division. NIST provides an executive officer to direct the administrative affairs of JILA, some administrative and technical support staff, and a Visiting Fellows Program. The University of Colorado component of JILA includes faculty from the departments of physics, chemistry, and astrophysical, planetary, and atmospheric sciences (APAS).

There are 26 faculty in JILA, known as JILA fellows, who set JILA 's scientific and administrative policy. Of the present 26 fellows, 16 are State of Colorado-supported (full academic salary) faculty members; 5 are in physics, 2 are in chemistry, and 9 are in APAS. There are 10 active NIST fellows of JILA. Of these NIST scientists, seven are lecturers or adjoint professors in physics, two are adjoint professors in chemistry, and one is an adjoint professor in APAS. These adjoint appointments are a required part of the position and are intended to allow the NIST scientists to supervise graduate students and postdoctoral associates, teach courses, and participate in department affairs. In addition to the fellows, JILA is currently home to 81 graduate students, 55 University of Colorado research associates (postdoctoral scholars), and 5 National Research Council postdoctoral associates. There are 44 administrative and technical support staff, 13 senior scientific staff, and 10 visiting fellows. The total number and distribution of JILA staff have remained relatively constant for several years, except for an increase in the proportion of postdoctoral associates to graduate students.

It must be stressed that the NIST fellows in JILA do not have any additional permanent NIST employees in their groups, as is the case elsewhere in NIST. Instead, their groups typically consist of postdoctoral associates and graduate assistants and the occasional visitor. Since these researchers are supported largely by outside grants, NIST achieves considerable leverage in the activities of the fellows it supports at JILA.

According to the memorandum of understanding, JILA is “primarily academic and scholarly” in nature. The 1976 addendum to the memorandum summarizes:

It will, in these fields (noted as atomic and molecular science, astrophysics, chemistry, precision measurement, etc.) continue to provide for the education of scientists at the graduate and postdoctoral levels. It will, through the collaboration

of its scientists from the National Bureau of Standards and the University of Colorado, and through research and teaching in these fields, continue to be cognizant and responsive to the missions of its parent organizations as well as the national needs which are affected by these missions. Toward these ends it will continue to promote close interactions with its colleagues in both institutions.

The following is the function statement for the Quantum Physics Division from Department of Commerce administrative orders:

Engages in long-term, high-risk research in quantum physics and related areas such as atomic and molecular collisions, spectroscopy and radiative interactions, chemical physics, optical and laser physics, gravitational physics, geophysical measurements, radiative transfer, and solar physics; performs basic, highly accurate measurements and theoretical analyses in these areas essential to the foundations of the Nation 's science and technology; develops the laser as a refined measurement tool; applies state-of-the-art methods to measurements and tests of the fundamental postulates and natural constants of physics; engages in research in atomic, molecular, and chemical physics leading to the determination of key techniques and data essential to understanding, predicting, and controlling the properties of excited and ionized gases and the pathways of chemical processes; improves the theory and instrumentation required for measurements of astrophysical and geophysical quantities such as the cosmic distance scale, earth' s gravity, and terrestrial distances; maintains, through its association with the Joint Institute for Laboratory Astrophysics (JILA) at the University of Colorado and JILA's Visiting Fellows Program, active contact with and expertise in advanced research in physics; and makes its scientific knowledge available to many other areas of NIST and to industry through publications, visits and exchange of personnel.

The current strategic plan of the QPD as presented to the panel by JILA is to orient ongoing research toward a number of important objectives, including smaller, faster, and more reliable electronic and optoelectronic devices; improved optical data transmission and manipulation using nonlinear media; more sensitive and versatile optical and spectroscopic sensors for chemical detection, measurement, and process control; better physical standards for manufacturing; and new improved sources of and more efficient use of energy.

JILA's financial support is derived from three major sources: NIST, the University of Colorado, and outside contracts and grants (as well as visitors' salaries paid by external sources). Combined, these outside sources provide 53 percent of JILA's total support, and NIST and the University of Colorado provide 24 percent and 22 percent, respectively. In the last 4 years, the University of Colorado contribution has grown by 32 percent, and outside support has increased 26 percent and the NIST component 24 percent. The total support of JILA from all sources has increased 27 percent to $17.4 million for fiscal year 1993.

Under the memorandum of understanding, the responsibility for providing JILA with space rests with the University of Colorado. The Institute is housed in a building containing about 61,000 square feet of space, of which 16,000 is a new wing built in 1987. NIST and the University of Colorado share the cost of operating the building.

JILA's 190 scientists and graduate students and 44 technical and administrative staff require laboratories, offices, shops, and computer facilities. Any significant increase in personnel or expansion of research would raise the question of whether space can be made available. JILA management is acutely aware of this issue and has taken steps to address it (see below, “JILA Responses to Fiscal Year 1992 Recommendations”).

The missions and strategies discussed above have been successfully and synergistically implemented over the years. This has resulted in a concentration of excellence in a number of related research areas that would have been virtually impossible for either NIST or the University of Colorado to achieve on its own. In the subpanel 's opinion, the combined contributions and interactions of the University of Colorado and NIST scientists have fulfilled the missions of each parent organization far better than either contingent could have done on its own.

The panel was uniformly impressed with the world-class caliber of the technical and scientific personnel within JILA. The younger tenured members of JILA are enhancing the reputation for quality, high-impact research established by their more senior colleagues. This is evidenced by their winning the majority of the five major named awards (by the American Physical Society, Optical Society of America, and Department of Energy) and the three NIST awards bestowed on JILA fellows in the last 2 years. This clearly bodes well for the future, provided JILA can continue to offer sufficient attractions to retain the services of outstanding younger members, who frequently receive attractive offers from top universities and research organizations.

In the panel's opinion, the NIST component of JILA has fulfilled its mission well over the years and continues to do so. The present strategy of the QPD contains an appropriate emphasis on NIST's mission of enhancing the short- and long-term competitiveness of U.S. industry, an objective that seems in harmony with the statement in the JILA mission that JILA “continue to be cognizant and responsive to the missions of its parent organizations as well as the national needs which are affected by these missions.” However, the current QPD mission statement does not explain how the various groups within the NIST component of JILA fulfill the current NIST mission of enhancing industrial competitiveness, particularly in the long term.

JILA is a complex organization in which a number of identifiable groups are intermixed in a symbiotic relationship. In addition to the JILA fellows, there are visiting fellows, postdoctoral associates, graduate students, undergraduates, and technical and administrative support staff. The panel did not have sufficient time during its site visit nor the specific charge to consider thoroughly whether the contribution of these groups to JILA is currently optimized and whether in return JILA is meeting their needs. Nevertheless the subpanel believed it important to spend approximately 1 hour with a few randomly selected members of each group to check for obvious problems and to get an overall impression of the current situation. The panel findings for each group are discussed below.

Visiting Fellows. The Visiting Fellows Program is a unique JILA institution that brings senior scientists to JILA for extended visits. Since its inception 30 years ago, the program has become internationally renowned, and more than 290 senior scientists from the United States and 29 foreign countries have participated. In response to previous panel recommendations, JILA has increased the representation of minorities and women among the fellows and has instituted provisions to encourage short-term industrial visitors (see below, “Recommendations”).

The visiting fellows whom the panel interviewed expressed praise for the program's administration and appreciation for help in establishing and becoming familiar with the computing facilities. The fellows were very appreciative of the opportunity to visit a high-quality institution like JILA.

Postdoctoral Associates. Postdoctoral associates are supported to work on a particular project (NIST postdoctoral associates have somewhat more flexibility than do the University of Colorado postdoctoral associates) and generally plan to spend 2 or 3 years at JILA, generate some good publications from their project, and then move on to a permanent job. In the past, JILA postdoctoral positions have been stepping-stones to more permanent academic jobs, with about 45 percent of the JILA associates following this pattern (higher than the percentage of JILA graduate students who take academic positions). Historically, only about 10 percent of JILA

postdoctoral associates take industrial positions, and so the panel was surprised to find that those interviewed were seriously considering industrial positions as their ultimate career objective.

Graduate Students. The three graduate students the panel interviewed were all satisfied with their thesis projects and supervisors at JILA. They did not share the concern about employment upon graduation that many graduate students at other institutions have recently voiced. The female graduate student interviewed observed that the attrition of females in science graduate schools is high generally and that the University of Colorado was no exception. In common with women in all of the groups the subpanel spoke to, however, she felt that the fellows and administration of JILA were very supportive.

Staff. As the number of people in JILA has increased over the years, older staff members in particular have noted that the feeling of family has largely disappeared from JILA and that frequent personal contact with fellows has decreased, necessitating more formal channels for communication and greater awareness from the fellows of the need to inform staff of developments under consideration. Greater concern for the career development of administrative and technical staff could increase their productivity and commitment to the institution.

There are varying degrees of satisfaction with respect to the adequacy of the equipment provided for staff. Nevertheless, there was universal agreement from all interviewed that the JILA staff continues to do an exceptional job.

Fundamental and Precision Measurements Group. This group is involved in high-precision measurements and metrology, particularly involving lasers, time measurement, and gravitational measurements.

Several of the techniques used or being developed in this group could prove useful to U.S. industry. Several of the group's precision experiments are currently limited by vibration; active servo control systems under development by the group to provide greatly reduced vibration, particularly at frequencies around 1 Hz, have enormous potential applications. For example, these techniques could achieve and maintain the desired geometry of large space structures, like reflectors for power relay satellites in geosynchronous orbit. Techniques for measuring and reducing small accelerations at low frequencies can be used for vibration isolation in equipment to manufacture and characterize semiconductor devices and to remove limitations in position measurements applied to small separations between individual elements of complex semiconductor devices.

Other recent work may lead to the development and application of transportable phase stable lasers with very high spectral purity, tunability, and low cost for intercomparison of optical frequency standards for optical frequency clocks. NIST's automated computer time service uses the telephone system for automated setting of clocks in digital systems to achieve millisecondlevel synchronization as synchronization standards for telecommunications systems. Workshops for industry on time and frequency and synchronization standards are well attended and indicate the interest of industry in subjects tailored to meet their near-term and practical needs. A

CRADA was executed between NIST and Micro-g for JILA to develop a free-fall absolute gravimeter, the JILA FG-5, with consulting assistance provided by JILA staff.

Work leading to a high-sensitivity geophysical bore-hole tiltmeter with stability of calibration over several years will aid in earthquake hazard reductions. A JILA fellow consulted for GEO Research Institute on a contract with Allied Signal Corporation to develop the bore-hole gravimeter. The gravity wave-driven technology required an active isolation system that could be of value to small-scale lithography and other manufacturing processes. A long-period spring system developed as part of a JILA student's doctoral thesis is applicable to seismic signals that require a large response below resonance to achieve high sensitivity and is the subject of a patent application. These examples show that technologies developed at JILA are relevant to industry and that significant benefits could come from industrial collaborations.

Atomic and Molecular Collisions Group. The Atomic and Molecular Collisions Group has traditionally been a strong component of JILA, which has been a world leader in the study of atomic and molecular collisions. Recent theoretical progress relating to quantum optics has been particularly outstanding; however, there is considerable cause for concern about the future of this effort. Of the 10 fellows who were interviewed, 3 have already retired, 1 has left JILA to take up a new position within NIST, and another is expected to leave within the next 12 months. Because of the continued participation in research by the retired fellows, there has as yet been no diminution in the quality or quantity of the research output; however, continuation of this excellent record and the symbiotic relationship between theory and experiment in this area will be jeopardized unless careful attention is given to restaffing this group.

A great strength of JILA's Atomic and Molecular Collisions Group has been the interaction between experimentalists and theorists. The subpanel was pleased to see that this complementarity has been maintained and found many examples of progress on difficult problems that had used this interaction. The efforts on time-delayed spectroscopy of two-level systems, cone emission, and four-wave mixing are examples. In studies of the basic properties of systems with two valence electrons, the importance of relativistic effects and electron correlation in both radiative and collision processes has been further elucidated in theoretical studies that are also closely linked to experimental efforts at JILA and elsewhere.

This group of researchers has continued to exploit its unique experimental capabilities. Pioneering experiments in the measurement of the cross section for excitation in electron-ion collisions have been carried out for both singly and multiply charged ions. This program is discovering unexpected phenomena and providing valuable data for applied plasma physics programs. The researchers' combination of laser and discharge experience has led to valuable experiments on energy pooling reactions, through which collisions of pairs of excited atoms lead to processes which cannot occur if only one atom is excited. Further information on inelastic heavy particle collisions in the gas phase and on surfaces has come from careful diagnostic studies of hydrogen, nitrogen, and argon discharges.

Interaction between the Atomic Physics Program and the Optical Physics Program has been especially fruitful in the 2 years since the subpanel 's previous assessment. Studies of the behavior of atoms in strong laser fields have led to increased understanding of the interference between one- and two-photon processes. Improved models of four-wave mixing and harmonic generation have led to additional flexibility in modifying the frequency of laser light. Study of laser-induced energy transfer has provided new understanding of atom-molecule collision

mechanisms and is paving the way for development of techniques for laser-controlled chemical processing. Experiments and calculations on collisions in particle traps are revealing new phenomena and are important in the development of improved techniques for laser cooling, a process whose fundamentals are being studied theoretically using a new quantum Monte Carlo technique.

JILA atomic physics researchers have played a leading role in assembling and expanding the atomic database for the magnetic fusion program. In recent years, this effort has been focused on the processes that occur in the relatively cool regions of the plasma near the diverters and limiters.

Plasmas are being used widely in industry in semiconductor manufacturing and surface engineering. JILA's atomic and molecular orbital theory researchers have led work in the analysis of the silane plasmas that are used in the deposition of amorphous silicon for solar panels, flat-panel displays, and other semiconductor applications. Several innovative JILA projects have addressed critical issues in plasma-surface interactions. This group of researchers has also demonstrated that hyperthermal beams of chlorine lead to enhanced etching of silicon without substrate heating, determined the surface properties of amorphous silicon produced through plasma-aided deposition, and shown that scanning tunneling microscopes can be used to create silicon nanocolumns as well as to probe surface structure, which could lead to efficient electron sources in field-emission diode arrays.

In view of the increased interest in industrial applications of low-temperature plasmas and the shift of many plasma physicists' attention from fusion to plasma processing, it is unfortunate that the gas discharge research at JILA is shrinking, since such research can make substantial contributions to the microelectronics and lighting industries.

The JILA parity nonconservation experiments touch on many technical areas, are at the heart of atomic physics, and address one of the most fundamental questions in particle physics. The exceptional progress and quality of the JILA measurements have been well recognized, as evidenced by the recently bestowed Davisson-Germer Prize and E.O. Lawrence Award for this work. Clearly these measurements should continue, since substantial improvements can still be made; recent experimental improvements should result in a new series of measurements with an error of less than 5 parts in 1,000. Calculational efforts are also in place to determine the relevant atomic matrix element to better than the current error of 1 percent. Different isotopes of cesium are also in use to eliminate an imprecisely known matrix element from some important comparisons.

The quest for the elusive goal of Bose-Einstein condensation has now shifted from hydrogen to heavier atoms, where a host of new trapping and cooling techniques can be used. The JILA approach uses low densities, much lower temperatures, and low-cost apparatus relative to those needed for hydrogen work. Many of the techniques involved have been developed and perfected at JILA, and so maximum expertise is being brought to this problem. Several unique ideas are involved in this attempt, and two JILA groups are following somewhat different paths toward this goal. The work is first rate and addresses a most fundamental problem.

A group of researchers at JILA is attempting to extend the techniques of laser cooling, developed originally for gas-phase experiments, into the solid state. Using GaAs wafers that could be mass-produced and solid-state diode lasers such as are found in compact disk players, they hope to achieve a fraction-of-a-watt cooling at temperatures below 100 K. This type of vibration-free refrigeration could overcome a major barrier to commercialization of high-

temperature superconducting devices and infrared monitors for industrial and environmental sensing.

JILA's excellent work on photorefractive materials has completely changed the perception of these materials from that of “black magic” to an understandable medium. This transition resulted from profound JILA theoretical work coupled with experimental demonstrations of the effects involved. The 1994 R.W. Wood Prize was awarded for this accomplishment. The distinctive differences between Kerr-type and photorefractive materials are now precisely understood. Based on the complete theory, new applications of photorefractive materials can now be confidently proposed, demonstrated, modeled, and made available for use.

Chemical Physics Group. The Chemical Physics Group comprises first-rate scientists whose creativity, productivity, and impact are clear. Their work covers diverse aspects of chemical physics that relate closely to the mission of JILA. The group's research ranges from studies of small-molecule structure and dynamics, to studies of clusters, to interactions of atoms and molecules with surfaces. The researchers are well integrated with related research efforts at JILA, sharing interests with the Atomic and Optical Physics, Fundamental and Precision Measurements, and Astrophysics Measurements Groups. The group is lively and vigorous, moving into new areas as scientific opportunities arise.

The group's fundamental studies of the structure and energetics of reactive species using photoelectron spectroscopy provide important new data on bond strengths, which have a direct impact on the modeling of complex reaction systems like combustion. These studies also provide new information about the energetics of triplet states that are otherwise inaccessible.

The group has a vigorous program studying the structure and dynamics of large and small clusters. Its combination of pulsed jets and high-resolution lasers has produced some of the most detailed data available on the structure and vibrational predissociation dynamics of small clusters. In many cases, these measurements push both scientific and technological frontiers. The group's study of large ion clusters using molecular beam and ultrafast laser techniques provides new information on dynamics in these special systems in which an ion behaves as if it were in a liquid, providing a model system for the onset of condensed phase behavior.

Other applications of these high-resolution spectroscopic techniques include the investigation of the dynamics of bimolecular reactions. In one set of experiments, a high-resolution infrared laser is used to detect products of reactions of photolytically generated chlorine atoms with molecules such as HCl, H₂O, and CH₄. The resolution and tunability of the infrared source allow a detailed determination of the population of various quantum states of the reaction product and simultaneously determine its recoil speed and direction from the Doppler profile of the absorption lines. The development of an injection-seeded optical parametric oscillator promises to carry these experiments into new regimes via this very narrow bandwidth and broadly tunable light. Other work in the Chemical Physics Group studies a broad range of important aspects of chemical reactions, including ion-molecule reactions, the orientation of ions in collision, the reaction dynamics of aligned atoms and molecules, the redistribution of energy in collisions, and the disposal of energy in chemical reactions.

The group's work on the interaction of atoms and molecules with surfaces probes several types of interactions, with a particular emphasis on semiconductor surfaces. One important advance is the development of a source of translationally energized chlorine atoms for investigating interactions with surfaces and reactive collisions with molecules. This work has also

proven to be an ionization technique for probing atoms and clusters above semiconductor surfaces during reactive etching. A series of theoretical efforts by visitors and permanent fellows enhances these experimental efforts. Calculations within the group on collisional energy transfer rates, the vibrational state structure in molecules, the vibrational predissociation rates of small clusters, and the dynamics of large clusters all tie closely to these measurements at JILA.

Astrophysical Measurements Group. JILA researchers have played a key role in the international Global Oscillations Network Group (GONG) and in the design of the complementary SOHO satellite mission, which is to be launched in a few years by the European Space Agency. The objective of this program is to monitor the motions of the Sun's surface accurately to infer the structure of the Sun's interior. Knowledge of this structure is essential for understanding the transport of energy, angular momentum, and magnetic fields in the Sun and other late-type stars.

The interpretation of the GONG and SOHO observations will require sophisticated theoretical modeling, and JILA scientists are making significant advances in the underlying theory of convective transport in the Sun. Simulations of convection on large scales have been carried out on a massively parallel computer. Such simulations serve to both push the technology of massively parallel computers and add to our understanding of complex physical phenomena such as convection.

A consequence of convection in the Sun is the formation of strong magnetic fields (more than 1,000 times the strength of the Earth 's) in the solar atmosphere and corona. By virtue of a recent appointment, JILA is now in a position to contribute to our understanding of these processes. Problems that have been addressed recently include the evolution of magnetic field structures from an equilibrium state to a nonequilibrium state as the field is twisted by the convective motions and the determination of the energy spectrum of the particles that are accelerated as a result of this process.

Magnetic fields play a central role in the interstellar medium as well as in the Sun. JILA scientists are elucidating the effects of magnetic fields in the interstellar medium, particularly on the structure of molecular clouds. These clouds, which are the birthplaces of stars, have masses up to several million times that of the Sun and are supported against the pull of gravity by static and turbulent magnetic fields as well as by turbulent motions. By modeling these turbulent motions as a superposition of waves, JILA scientists have shown that it is possible to determine how the energy is distributed throughout the cloud and how the cloud would respond to an increase in the pressure of the surrounding medium.

JILA scientists are widely recognized for their work on cool stars such as the Sun. Although most of a star's energy is emitted in thermal, optical, and infrared radiation, a small fraction is emitted as ultraviolet emission lines and nonthermal radio emission, which are indicative of activity on the star's surface. In the case of the Sun, this activity is associated with sunspots, solar flares, and small fluctuations in the solar luminosity. Because of climatological implications, it is of great importance to increase our understanding of stellar activity. JILA scientists pioneered the use of the Very Large Array for radio observations of cool stars, and they have been among the most successful users of the International Ultraviolet Explorer satellite for studies of these stars. A recent observation of the nearby cool star Capella with the Hubble Space Telescope has attracted great attention; despite the spherical aberration that plagued the telescope until recently, it was possible to obtain a spectrum of such sensitivity that the abundance of deuterium in the local interstellar medium could be measured with greater accuracy than was

possible before. Deuterium is a relic of the Big Bang, and its abundance indicates the density of baryons in the universe. This new measurement confirmed previous measurements that imply that the amount of visible matter in the universe is too small to reverse its expansion.

JILA scientists have a very strong group working in the area of massive star formation and evolution. Massive stars—those of spectral types O and B—evolve rapidly and are therefore found clustered in OB associations near their birthplaces. Current research at JILA has determined the relative birthrate of these stars as a function of mass within the nearby galaxy, the Large Magellanic Cloud (LMC), revealing evidence that the initial mass function differs from its form in our own galaxy. Such studies have important consequences for theories of star formation and the appearance of galaxies undergoing rapid bursts of star formation, the so-called starburst galaxies. Recently completed work on the extended environments of OB associations has revealed evidence for large-scale bubbles blown in the immediate vicinity of young associations by the combined radiation and stellar wind pressure of the newly formed stars.

Wolf-Rayet (W-R) stars are thought to be the evolutionary end-points for the most massive stars. JILA scientists have led the study of W-R stars for decades. They have recently shown that the “Baldwin Effect,” an inverse correlation between the equivalent width of a carbon emission line and the underlying continuum radiation, seen in quasistellar objects and some Seyfert galaxies, is also seen in some W-R stars. The correlation can be used to deduce the source 's luminosity and hence its distance. W-R stars may also prove a testbed for understanding the origin of the effect itself.

The 1987 supernova explosion in the LMC presented astronomers with a nearby example of one of the most energetic events in stellar astronomy. The JILA theory group has taken an active role in interpreting the observations and drawing the conclusions of many other studies together in the form of a major review paper on the supernova. The JILA group has also worked intensively on the interpretation of the optical spectra from the event. They have shown that soon after the explosion, the combined heating of radioactive Fe, Co, and Ni resulted in the formation of low-density “nickel bubbles.” They have also shown that 2 or more years after the explosion, the radioactive decay can no longer explain the observed luminosity; an additional energy source is needed. They conclude that the most likely source of this additional energy is emission from the metastable He in the dense clumps.

Embedded in JILA's ongoing work are advanced capabilities and activities that can have significant benefits to industry if the methodologies, instrumentation, and experimental and analytical procedures are suitably translated or adapted to industry's needs. Potential applications include metrology and active control to maintain the desired geometry of large space structures, active vibration isolation techniques for high-precision manufacturing equipment such as submicron lithography, and transportable phase-stable lasers for the intercomparison of optical frequency and length standards.

Cognizant of the changing role of NIST, the subpanel recommended in its fiscal year 1992 assessment that JILA fellows increase the level of “meaningful scientific interactions with industrial scientists ” (p. 178). Unfortunately, as detailed below in “JILA Responses to Fiscal Year 1992 Recommendations,” the University of Colorado review gave a contradictory

recommendation and JILA management did not begin to immediately carry out a policy to stimulate industrial interaction. In addition, legal issues have in some instances complicated, and thereby discouraged, some interactions. Most of the specific industrial interactions that occurred resulted entirely from the initiatives of individuals. Recent efforts by JILA management to stimulate and foster interactions with industry, detailed below, appear well thought out and will likely increase the number and impact of such interactions. Judged against this background, JILA's past and current activities in this area are to be commended.

Operationally, the changing climate is best illustrated by the various CRADAs presented to the subpanel that have already been established or are in process. These agreements provide an excellent, flexible mechanism for interactions between government and industry. The subpanel commends JILA fellows already pursuing these opportunities. Other opportunities will undoubtedly arise to create additional CRADAs, and the subpanel encourages efforts by NIST management to facilitate this process.

Following are some examples of individual interactions with industry in addition to CRADAs.

As mentioned above, the Gas Research Institute arranged with NIST for the consulting services of a JILA fellow on a contract with Allied Signal Corporation to develop a bore-hole gravimeter. Newly developed technologies including atom interferometers, zero-length springs, and a vibrating quartz beam are being considered for this application. Such an instrument is intended for use in petroleum exploration.

In collaboration with other institutions, JILA scientists are involved in a project to numerically simulate the processes of three-dimensional turbulence over a broad dynamic range of spatial scales. Currently, such calculations are at the edge of what is tractable with the largest vector supercomputers or massively parallel machines. Project staff members have established close working relations with a number of computer firms developing massively parallel machines, including Thinking Machines, Kendall Square, Intel, and Silicon Graphics. Collaboration has provided these companies with codes sufficiently challenging to test their machines and with a range of monitoring and performance assessment tools that have pinpointed critical or potential bottlenecks in the high-performance machine designs. In addition, the collaboration with Silicon Graphics involved assembling on its manufacturing floor a unique array of 20-processor Challenge XL machines in a three-dimensional torus and testing them for 1 month, a collaboration that is scheduled to continue.

Historically, NIST (and previously NBS) has played an important role in the collection, critical evaluation, and publication of scientific data. Part of this activity was initiated at JILA, focusing on collision cross sections and related data. This aspect of JILA's work, and similar work throughout NIST, lacks glamour but is a key element in the promotion of science and technology. It is particularly valuable to industry, where often the data user is unfamiliar with the field and may not have easy access to the literature. NIST's increasing commitment to serving industry should embrace this existing activity and ensure its vigor with adequate funding. In JILA's case, the data center staff consists of the director and a full-time assistant. Addition of a full- or part-time programmer would allow the director to concentrate on new projects and could significantly enhance the center's overall productivity.

The JILA Visiting Fellows Program, supported by NIST, has a worldwide reputation for excellence. It has allowed hundreds of scientists to benefit for useful periods from the facilities and personal interactions available at JILA. Most visiting fellows have come from academia,

usually on sabbatical leave, which allows them to stay the requisite period of 6 to 12 months. This constraint of at least a 6-month stay has probably contributed to the relative dearth of visitors from industry. In recognition of this problem, JILA is instituting a new component to the Visiting Fellows Program. Some of the program's funds will be used to host a series of industrial fellows, for a shorter period left partly to the visitor's discretion. The subpanel commends JILA for this initiative.

A former director of research and development at IBM has stated that the transfer of technically trained people is by far the best means of technology transfer to and within industry. From this perspective, the NIST component at JILA has been very successful at transferring cutting-edge technology to industry and other government laboratories: 40 percent of the recent postdoctoral associates and 54 percent of recent graduate students are now employed at such institutions.

An important component of JILA's current effort to improve its involvement with industry is the creation of a new staff position with direct responsibility for promoting industrial interactions. The holder will spend approximately 40 percent of his or her time on these duties (see below, “JILA Responses to Fiscal Year 1992 Recommendations”).

The following are the subpanel's recommendations for JILA.

• JILA should continue to develop plans and strategies to help U.S. industrial competitiveness, particularly in the long term. The subpanel found this appropriate in view of the national interest as well as the new emphasis on economic impact in NIST and in federal funding of scientific research generally.

• The Quantum Physics Department should develop an improved program to better focus its technical and scientific capabilities to benefit U.S. industry. The subpanel recommends that consideration be given to the following: (1) metrics of effectiveness of industrial interactions, e.g., CRADAs, patents, invitations to consult or to attend relevant meetings, or service on national or international standards committees; (2) active outreach, such as hosting seminars, schools, and meetings focusing on industrial problems and opportunities, and supplementing the Visiting Fellows Program to allow short-term visits from industry and visits of JILA fellows to industry; (3) broadening of JILA's reward structure to reward activities that have short- or long-term impacts on U.S. industry; (4) continued emphasis on long-range high-technology development and metrology projects; and (5) incorporation of elements of this QPD program into any similar plan for all of JILA, where this is agreeable to both parties, making this QPD program open to as much of JILA as possible.

• NIST management should provide appropriate leadership to promote further interaction of QPD and JILA fellows with U.S. industry. The subpanel recommends consideration of the following: (1) resources (e.g., multiyear grants) to support research groups of NIST and JILA fellows as they reorient toward greater service to industrial goals; (2) initiation of industrially oriented research by providing relevant infrastructure such as a fabrication

workshop for multilayer optical coatings and crystal cutting and polishing; and (3) professional rewards and recognition to fellows whose work is judged especially valuable to increasing the short-or long-range competitiveness of U.S. industry.

• While working to increase its industrial interactions, NIST management should assure continued opportunity for NIST investigators to find OA support for major portions of their research effort.

• NIST management must take greater initiative in maintaining contact with University of Colorado personnel who have management responsibility for JILA. An excellent vehicle for this would be consultations during the process of revising the QPD mission statement to reflect current NIST goals more accurately.

• JILA should encourage technical interactions of fellows, particularly the NIST fellows, with colleagues at Gaithersburg, Maryland, and other NIST facilities and should find resources for appropriate visits of sufficient length for meaningful collaboration.

• JILA should continue to identify and maintain informal contact with outstanding women and minority candidates for faculty appointments in fields of interest to the institute. In view of the lack of any NIST fellow in such a protected class, it would be desirable for NIST to make special efforts to attract and support such a candidate.

• The subpanel emphasizes as strongly as possible that all changes implemented in QPD must be carried out in a manner that maintains the ability of NIST and the University of Colorado to attract and retain world-class investigators in JILA.

The subpanel was favorably impressed with the responses of JILA to the previous recommendations; all were met with productive responses or at least satisfactory efforts. Given below are the subpanel's fiscal year 1992 recommendations for JILA (quoted from the fiscal year 1992 assessment), with JILA's responses.

• “JILA should set up a standing committee to identify on a continuing basis outstanding women and minority candidates for faculty appointments in fields of interest to the institute” (p. 176). The JILA conducted a thorough search for an outstanding faculty member or fellow in a protected class. The subpanel was disappointed that NIST was unable to make available the resources to support a new hire, and the search did not identify any candidates in the only area (optical physics) where an appointment rostered in a University of Colorado department was available. However, JILA was able to add a new fellow (she remains an APAS faculty member).

• “JILA should redouble efforts to recruit members of protected classes for graduate work and for its Visiting Fellows Program” (p. 177). JILA has done an excellent job, adding five

protected-class fellows in the last 2 years. Progress in adding graduate students has been less dramatic, since they are admitted by the various departments and not by JILA directly.

• “Both human and space costs should be carefully considered whenever an increase in the number of JILA fellows groups is contemplated ” (p. 177). This recommendation was followed in two appointments, the only new appointments since the 1992 assessment.

• “The fellows should consider whether it is in the long-term interest of JILA to introduce limitations on the size of individual groups ” (p. 177). After discussing the matter at some length, the fellows, by a small margin, decided against drafting policies for size limitation. Policies have been established to limit space use by retired fellows and long-term visitors. The subpanel considered this a satisfactory response for the time being.

• “JILA fellows should consider methods by which meaningful scientific interactions with industrial scientists could be increased” (p. 178). This recommendation was counterbalanced by a contemporaneous recommendation by the University of Colorado review of JILA warning against industrial contacts that might detract form the basic research mission of JILA. The subpanel notes with displeasure the lack of any effort by NIST and JILA management to resolve this contradiction.

The University of Colorado administration has appointed a new dean, who takes the position that industrial interactions are highly desirable. Also, NIST management has now made clear that emphasis on industrial interaction, arising from the 1988 revision of its mission, applies without exception to all divisions. The subpanel observes that JILA has responded commendably to this newly concerted leadership. It has organized meetings to collect ideas for stimulating such interactions, and a committee to implement these suggestions has been formed. A member of the JILA staff has been supported in studies to earn an MBA degree with an emphasis in technology transfer, and he is expected to play a major role in this evolving thrust area. A number of productive interactions with industry, including several CRADAs involving NIST fellows of JILA, have already occurred. Given earlier conflicting demands from NIST and the University of Colorado, the subpanel commends JILA for its vigorous and ongoing response to this challenging recommendation.