Nuclear Physics The Core of Matter, The Fuel of Stars (1999) / Chapter Skim
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Pages 172-196
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From page 172... ...
172 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS 172 8 Nuclear Physics and Society INTRODUCTION Society supports fundamental research in the expectation of benefits that support national priorities. These benefits take many forms.
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NUCLEAR PHYSICS AND SOCIETY 173 and national security. Beyond these direct applications is the general benefit that arises from pressing forward the frontiers of high-technology development.
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174 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS and of some others with a good chance to become important in the future -- are given here. HUMAN HEALTH Technologies emerging from nuclear research have an important impact on human health and have resulted in a new field, nuclear medicine.
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NUCLEAR PHYSICS AND SOCIETY 175 Over 20,000 patients have been treated with protons, mostly at accelerators originally built for physics research. Now, physicists are designing accelerators optimized for cancer therapy; one has been in operation since 1990 at Loma Linda Hospital near Los Angeles, and many others are in various stages of planning and construction, both in the United States and overseas.
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176 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS given us x rays, computerized axial tomography (CAT) , nuclear magnetic resonance imaging (MRI)
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NUCLEAR PHYSICS AND SOCIETY 177 FIGURE 8.1 SPECT image of a man (front and back) , showing increased uptake of a radioactive barium tracer as bright spots.
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178 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS niques that have had enormous impact on diverse areas of science and technology. Even in the earliest experiments, it was found that measurements of nuclear magnetism were affected by the environment.
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From page 179... ...
NUCLEAR PHYSICS AND SOCIETY 179 nized with breathing. MRI with polarized nuclei provides the only imaging method now available for examining lung function.
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180 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS sufficiently high energy so it could be identified at its natural level of about 5 atoms in 1013 atoms of stable krypton. In biological applications of AMS, 14C can be used as a tracer with one million times the sensitivity of conventional scintillation counting.
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From page 181... ...
NUCLEAR PHYSICS AND SOCIETY 181 tion may make it possible to extend studies of solar activity backward 10,000 years in time, compared to the 400-year record currently available. A determination of whether solar variation could be partly responsible for climate variation may then be possible.
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From page 182... ...
182 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS Measured concentrations of oxygen isotopes in Greenland ice cores show that large changes were common near the end of the last ice age. Dating of organic glacial remains in New Zealand using 14C indicates that these large changes were global in nature.
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NUCLEAR PHYSICS AND SOCIETY 183 the accident, its half-life is so short (8 days) that it was impossible to repeat or extend these measurements.
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184 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS recently an alpha-proton-x-ray analyzer installed in the Mars roving vehicle Sojourner analyzed the composition of martian rocks (Figure 8.5)
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From page 185... ...
NUCLEAR PHYSICS AND SOCIETY 185 low-energy nuclear reactions, such as the deuteron plus triton reaction, bombard an unknown sample with the neutrons, and detect the presence of specific materials tagged by their characteristic gamma rays. The known dependence of total interaction probabilities on material provides another possible tag.
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186 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS interaction of neutrons with reactor fuels and materials, and of the decay properties of many of the radioactive nuclei that are formed. To provide this information, the DOE operates a Nuclear Data Program that, in the context of an international collaboration, is charged to collect, evaluate, and tabulate data useful for applications and for fundamental research.
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NUCLEAR PHYSICS AND SOCIETY 187 Since the 1970s, new construction of power reactors in the United States has come to a standstill. Concerns about operational safety and waste disposal have overshadowed the inherent advantages of nuclear power.
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188 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS inherently safe, and the long-lived waste is transmuted to short-lived nuclei in the process. A 1996 design study concluded that a 1-GeV, 0.03 ampere beam requiring 60 million watts of input power would produce 675 million watts of electric power, amplifying the input power by about a factor of 10.
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NUCLEAR PHYSICS AND SOCIETY 189 deposited. As a result, many reaction probabilities -- for charged particles, x rays, gamma rays, and neutrons -- as well as the nature of the beta-decay products of fission fragments, are needed to fully simulate the performance of a nuclear weapon.
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From page 190... ...
190 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS FIGURE 8.7 Proton radiograph of a chemical explosion, taken at the Los Alamos Neutron Science Center (LANSCE)
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From page 191... ...
NUCLEAR PHYSICS AND SOCIETY 191 the element californium to measure the attenuation of the neutron flux by light elements in the object being assayed. EDUCATION OF THE NATION'S TECHNICAL WORKFORCE Education of the next generation of technically sophisticated citizens and the training of scientists who can contribute to society have high priority in the nuclear physics community.
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192 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS more quantitatively. These records, summarized in Figure 8.8, are probably typical of the field as a whole.
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NUCLEAR PHYSICS AND SOCIETY 193 case of nuclear physics, the production of Ph.D.s has been stable, and it appears that their employment opportunities have been relatively constant over at least the past decade. Graduate Student and Faculty Demographics A number of surveys of people active in basic research in nuclear science have been carried out over the past 20 years, some based on questionnaires sent to essentially all funded researchers, and others on statistics provided by the funding agencies.
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194 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS Research Semester and the Undergraduate Student Research Participation program involve students in nuclear physics projects. With the American Chemical Society, the DOE has developed an intensive summer school program that exposes students to research in nuclear power, waste disposal, nuclear nonproliferation, radiation safety, and nuclear medicine.
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From page 195... ...
NUCLEAR PHYSICS AND SOCIETY 195 Contact with Teachers and Students in High Schools Students often perceive science and mathematics as formidable and as unpopular with their peers. This situation can be improved only if one addresses both the perception of science by young people and the quality of their science education.
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From page 196... ...
196 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS nuclear physics, which involves the most fundamental aspects of nature and is not directly focused on societal issues. If one examines the contributions outlined above, three threads running through them can explain this result.
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