Current Status of Neutron-Scattering Research and Facilities in the United States (1984) / Chapter Skim
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Pages 90-102
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From page 90... ...
6. FUTURE OPPORTUNITIES: FACILITIES AND RESEARCH Based on the preceding scientific summaries, a number of needs and opportunities for U.S.
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From page 91... ...
for time-of-flight applications, are necessary for the successful development of a new generation of instruments at both steady-state and pulsed sources. Moreover, a healthy and fully competitive U.S.
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From page 92... ...
that much of the spectroscopy at energies of 100 meV or higher will be performed on pulsed sources, the study of strongly dispersive high-energy excitations (e.g., high-energy spin waves, Stoner excitations) may often be done best at a steadystate source equipped with a hot source.
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From page 93... ...
characterization of the nature of the ordering and excitations of materials undergoing cooperative nuclear spin orientation at low temperatures. CHEMISTRY Most of what has been accomplished to date in neutron spectroscopy of molecules in condensed systems has only scratched the surface of what it is possible to do with neutrons in this area -- this will clearly be one of the major growth areas of neutron-scattering research in the future.
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From page 94... ...
be noted that much of future activity in neutron chemical spectroscopy will involve the use of difference spectra and isotopic substitution, where the signal from the species of interest is small compared with that from the surrounding media. This, combined with the fact that often the sample sizes available for spectroscopic studies of new novel compounds are very small, will require development of much more sensitive instrumentation and higher-intensity sources than are currently available.
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proteins, which must be explored to probe fully the structure of biological systems. Low-resolution crystallography clearly requires improved instruments and higher-flux sources of subthermal neutrons.
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POLYMERS As summarized in Chapter 5, many fundamental questions that are also of technical importance in the polymer field could be answered if low-wave-vector (q) and very-high-resolution elastic and inelastic neutron-scattering instruments using high-intensity cold-neutron beams are made available in the United States.
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From page 97... ...
related to tertiary oil recovery and other industrial applications. More-sensitive instruments would also be essential for the study of interfacial behavior of polymer membranes that have potential for future materials separation and electronic applications.
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processing, behavior, and reliability of advanced structural materials. NEUTRON OPTICS There is considerable motivation to develop much larger perfect crystal interferometers having dimensions of a meter or more, with independently oriented and positioned beam splitters.
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From page 99... ...
addition, it is clear that time-of-flight spectroscopy above the thermal neutron range will rapidly become the province of these sources, as improved instruments and higher peak intensities are achieved. However, competitive application of pulsed sources to subthermal neutron-scattering research and to studies of the dynamics of ordered or single-crystal specimens will require the development of new-generation sources and instrumentation.
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From page 100... ...
Concluding Remarks One of the clear conclusions that emerges from the recent rapid advances in neutron-scattering instrumentation and sources abroad, and from the more modest developments in the United States over the past few years, is that there is a much broader community, covering many disciplines, that needs and will respond to new and modernized capabilities in neutron-scattering research. Thus, it seems clear that the provision of a new generation of neutron instruments outlined above would more than double the existing neutron-scattering user community, particularly if instrument development is combined with incremental personnel resources to allow a more effective effort for the assistance of users.
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From page 101... ...
Our examination of existing U.S. neutron sources suggests that a program to allow the United States to achieve an internationally competitive position with other industrialized nations in neutron-scattering research would require an increase from all funding sources of an average of ~$15 million/year (in fiscal year 1983 dollars)
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From page 102... ...
a new reactor, it would be possible to increase neutrons at the sample position for many experiments by an order of magnitude over present generation reactors. Moreover, one advantage of a vigorous testing of pulsed sources and related instrumentation is that new accelerator advances may allow the achievement within the next 15 years of pulsed sources with peak thermal fluxes of ~1017 neutrons/cm2-sec and average fluxes above 1014 neutrons/cm2-sec.
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