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Pages 150-171

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From page 150...
... 150 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS 150 7 The Tools of Nuclear Physics INTRODUCTION Nuclear physics is a science driven by experiment, so its progress depends critically on advances in instrumentation. New developments in accelerators, detectors and their associated electronics, data acquisition systems, and computers for data analysis have been the bases for rapid developments in the field and provide the technical underpinnings for today's thrusts in nuclear physics.
From page 151...
... THE TOOLS OF NUCLEAR PHYSICS 151 needed for nuclear physics, detectors of greatly varying characteristics have been and continue to be developed for a spectrum of experimental observables. These range from the high-resolution detection of optical radiation at eV energies in studies of nuclear hyperfine structures, to sophisticated multidetector arrays needed to disentangle thousands of reaction products in high-energy nuclear collisions, and to scintillation detectors of thousands of tons buried deep underground to register the most elusive particles in nature, the neutrinos coming from the cosmos, the Sun, or from accelerators.
From page 152...
... 152 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS BOX 7.1 The Institute for Nuclear Theory The formulation of our theoretical understanding of nature and frequent, detailed discussions between theorists and experimentalists, are key elements to progress in physics. About a decade ago, with CEBAF and RHIC on the horizon, the Nuclear Science Advisory Committee recommended establishing a center for nuclear theory.
From page 153...
... THE TOOLS OF NUCLEAR PHYSICS 153 ly interacting many-body systems, and connections between high-energy and lowenergy precision measurements of the weak interaction. The INT workshops, which typically run from 2 to 5 days, attract another 200 visitors each year.
From page 154...
... 154 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS Accelerator Center (SLAC) , and continue to be involved in measurements at Fermilab and other high-energy facilities around the world.
From page 155...
... THE TOOLS OF NUCLEAR PHYSICS 155 Relativistic Heavy Ion Collider (RHIC) , the first high-energy heavy-ion collider, now nearing completion at Brookhaven National Laboratory (BNL)
From page 156...
... 156 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS FIGURE 7.2 Schematics of the two principal concepts for the generation of energetic beams of shortlived nuclei (radioactive beams)
From page 157...
... THE TOOLS OF NUCLEAR PHYSICS 157 based on a superconducting helical dipole magnet design are allowing acceleration and complex manipulations of polarized beams. Electron cooling of ion beams in storage rings has greatly advanced, allowing precision in-beam nuclear physics measurements in storage rings with internal targets.
From page 158...
... 158 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS INSTRUMENTATION Major progress made in target and detector systems in recent years underlies many of the current advances in nuclear science. Polarized targets of light nuclei, produced either by atomic-beam techniques or by novel approaches using laserinduced polarization, have played an important role in fixed-target experiments, as well as in experiments using internal targets in storage rings.
From page 159...
... THE TOOLS OF NUCLEAR PHYSICS 159 FIGURE 7.3 Schematic layout of a magneto-optical trap, which uses a combination of a weak magnetic field and six intersecting polarized laser beams to capture radioactive atoms generated in a nuclear reaction. These atoms are captured by neutralization and thermalization of a low-energy radioactive ion beam.
From page 160...
... 160 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS sists of 100 large Compton-suppressed germanium crystals. Using its high efficiency for high-energy gamma rays, it has been possible to identify, unambiguously, the transitions linking states in the superdeformed and normally deformed potential minima.
From page 161...
... THE TOOLS OF NUCLEAR PHYSICS 161 FIGURE 7.5 The superconducting magnetic spectrograph S800 at Michigan State University. The target for the nuclear reactions is at the bottom left of the spectrometer structure.
From page 162...
... 162 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS Hall A Hall B
From page 163...
... THE TOOLS OF NUCLEAR PHYSICS 163 Detectors for the Quark Structure of Matter The program to elucidate the quark and gluon substructure of nucleons and nuclei requires large, high-quality spectrometers at high energies and momenta. At TJNAF, two of the three experimental areas house pairs of large magnetic spectrometers (shown in Figure 7.6)
From page 164...
... 164 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS Spectrometer Toroid (BLAST) , is under construction for a full exploitation of spin observables in intermediate-energy nuclear physics.
From page 165...
... THE TOOLS OF NUCLEAR PHYSICS 165 FI G U RE 7 .7 T he O ut -o f-P la ne -S pe ct ro m et er (O OP S)
From page 166...
... 166 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS PHOBOS is a smaller detector; its double arm spectrometers use small magnets with strong magnetic fields and high-spatial-resolution silicon detector planes. The detector focuses on hadronic signatures for the QGP at low transverse momentum.
From page 167...
... THE TOOLS OF NUCLEAR PHYSICS 167 Underground laboratories are utilized increasingly to solve specific problems in nuclear physics; they have been essential in some important major advances of the field, particularly for measurements requiring very low backgrounds. They are cleaned of contaminants and are well shielded from cosmic rays, thus providing the environment in which searches for incredibly rare events become possible.
From page 168...
... 168 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS for the Gran Sasso and indicated in Figure 7.9. The detector is based on liquid scintillation spectroscopy, a standard method for detecting particles in nuclear and high-energy physics, and aims at a precise measurement of the neutrino flux from the 7Be decay in the Sun.
From page 169...
... THE TOOLS OF NUCLEAR PHYSICS 169 developments, as for new accelerator technologies, provide a unique and challenging training ground for the future scientists in nuclear physics and related sciences, but also for the technical workforce of the nation in general (see Box 7.1)
From page 170...
... 170 NUCLEAR PHYSICS: THE CORE OF MATTER, THE FUEL OF STARS Quantum Monte Carlo Simulations of Nuclei Detailed predictions of the microscopic and global structures of nuclei, and of nuclear reaction rates are challenging because of the quantal nature of nuclei and the complexities of nuclear forces. Many new developments in computational physics, including some of the key developments in the quantum Monte Carlo methods now used in several branches of the physical sciences, were made to address these problems in nuclear physics.
From page 171...
... THE TOOLS OF NUCLEAR PHYSICS 171 The only known way to calculate quark-gluon bound states and dynamics is by numerical evaluation on a discrete space-time lattice of large dimension. This technique was originally developed by particle physicists and is now being applied widely to problems in both particle and nuclear physics.

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