Current Status of Neutron-Scattering Research and Facilities in the United States (1984) / Chapter Skim
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3. CURRENT STATUS OF NEUTRONSCATTERING FACILITIES IN THE UNITED STATES In this chapter we describe briefly the existing neutron-scattering facilities at the five National Laboratory neutron sources and two major university reactor facilities.
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qualitatively new research opportunities in a variety of fields. It should be noted that in general U.S.
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is small (48-cm diameter) , resulting in a thermal neutron density that is peaked outside of the core, where beam tubes tangential to the core provide neutron beams with low fast-neutron contamination.
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Intense Pulsed Neutron Source (IPNS) -- Argonne National Laboratory The Argonne Pulsed Neutron Source produces bursts of neutrons with a peak thermal flux of ~4 × 1014 neutrons/cm2-sec at a repetition rate of 30 Hz and is at present the most intense pulsed source in the world.
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by a Program Committee, which reviews proposals twice a year. Three additional instruments are under development: a polarized neutron instrument for studying refraction from surfaces; a diffractometer built to search for ordered nuclear moment arrangements in 3He below 1 mK; and a spectrometer for spectroscopy in the electron volt range.
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scattering research. The reactor geometry combines a split-core fuel arrangement and large vertical divergence (~100 min)
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Oak Ridge National Laboratory Reactors (ORNL) The High Flux Isotope Reactor (HFIR)
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In addition, ORNL operates a 5-m SANS instrument with an area detector and a two-axis diffractometer. Proposals for the NSF-supported SANS facility are reviewed by a special committee and scheduled as they are received; there is normally a three- to fourmonth waiting period.
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An improved triple-axis spectrometer and another diffractometer are expected to be built during the next 2 years, and an engineering study has been funded for a possible doubling of the reactor power. Weapons Neutron Research/Proton Storage Ring Facility (WNR/PSR)
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meets twice a year to decide on proposals for beam time. The total time available for neutron-scattering studies currently is 60 percent of the LAMPF operating schedule (6 months/year in 1982-1983)
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TABLE 1 Summary of Neutron Scattering Instruments Available in the United States A
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It should also be noted that aside from the facilities described above, there are ongoing state-of-the-art efforts at the various neutron centers in the development of area detectors, multilayer focusing and polarizing monochromators, focusing collimators, neutron interferometers and choppers, all of which are important for the development of advanced instrumentation for reactor or pulsed sources. While in some cases U.S.
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FIGURE 1 U.S. neutron-scattering research -- users and publications.
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No attempt has been made to identify scientists who might have used more than one neutron source. Also shown in Figure 1 are the number of publications in the 1977-1983 period.
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a healthy increase over the past 6 years (~33 percent) , these users now represent a considerably smaller percentage of the total community than in 1977 (~45 percent)
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student users at the various neutron centers. This number is both significant and encouraging since the education and participation of young scientists in modern neutron-scattering science is essential for the future health and vitality of the field.
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It is also interesting to note that a combination of the facility numbers in Table 1 with the user figures in Figure 1 gives about 10 users/instrument. This is rather close to the comparable ratios assumed for synchrotron facilities in the Report of the Subcommittee on U.S.
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FIGURE 2 Summary of users and publications from Western Europe.
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numbers is the dominant position of ILL, which accounts for about half of the users and publications in Western Europe. In fact, the figures show that the ILL alone has about 25 percent more "users" than the total for the United States.
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of the U.S. neutron centers, the U.S.
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