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1. CONCLUSIONS AND RECOMMENDATIONS CONCLUSIONS 1. In the last decade neutron-scattering research worldwide has shown a rapid expansion both in the number of users and in the diversity of disciplines and science to which neutron methods are being applied. This growth is due to the development of improved sources and new instruments, which have greatly enhanced the energy and wave-vector range, resolution, and sensitivity of neutron instrumentation. The neutron-scattering community in Europe more than tripled during the 1970s. By comparison, the U.S. community has doubled over the past 6 years, accompanied by a 150 percent increase in users from less-traditional areas--polymers, biology, and materials science. 2. In spite of some recent progress, the United States has fallen far behind Western Europe in the development of advanced facilities at research reactors, including modern applications of cold sources and guide-tube technology, focusing monochromators, and spin-echo and backreflection techniques. These advances have led to many fundamentally new applications of neutron scattering, which touch on all materials-related disciplines, including technologically The United States has maintained its important areas. competitive position and tradition of excellence in such areas as thermal-neutron triple-axis spectroscopy and chemical 1

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2 and biological crystallography and, for the present, is at the forefront in pulsed-source research. 3. Current U.S. reactors remain world class in terms of available thermal-neutron-beam intensities, and there are immediate opportunities to achieve an internationally competitive status in advanced instrumentation for both cold and thermal neutron scattering at a cost substantially lower than the recent European expenditures. Such modern facilities, combined with emerging applications of pulsed- neutron sources, would stimulate greatly expanded use of neutrons to meet new scientific and technological needs and opportunities until new-generation sources are developed. It should be noted that existing sources will be 20-25 years old by 1990. RECOMMENDATIONS 1. The Panel recommends that an immediate commitment be made to develop new state-of-the-art instrumentation at our high-performance research reactors to provide world- class capabilities in such areas as high-resolution and high-sensitivity neutron spectroscopy, small-angle scattering and diffraction, medium-resolution macromolecular diffraction, and diffuse scattering. This will require the extensive development and application of modern cold-source and guide- tube technology, focusing and polarizing monochromators, and area detectors. 2. The Panel recommends that adequate support be provided to allow full investigation and development of new pulsed- source instrumentation required to exploit the unique opportunities in condensed-matter research provided by the

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3 pulse structure, higher fluxes of epithermal neutrons, and expanded wave-vector range of spallation sources. 3. The Panel considers it essential that serious design efforts be started immediately for the development of next- generation sources, so that definite proposals are available by fiscal year 1988. The results of such efforts are essential as input to a broadly based user group, which should be established to recommend a coherent plan to meet the long- term neutron research needs of the scientific community. It is the view of this Panel that the National Academy of Sciences-National Academy of Engineering would be the most appropriate body to establish such an independent multidisciplinary advisory group.