SUPERHILAC/BEVALAC Lawrence Berkeley Laboratory Description of Facility The proximity of two existing accelerators at Lawrence Berkeley Laboratory (LBL)-the SuperHILAC and the Bevatron--has permitted a combination of accelerator capabilities not available anywhere else in ihe world. This combined accelerator system, called the Bevalac, is operated as a national research facility for studies in nuclear and atomic physics, nuclear chemistry, and astrophysics. In addition, one-third of the Bevalac operating time supports biomedical research. In 1974 the SuperHILAC (a linear accelerator capable of accelerating all elements to energies of 8.5 million electron volts per nucleon [MeV/AMU]) was connected by means of a beam transport line to the Bevatron, LBL's weak-focusing proton synchrotron. The SuperHILAC generates up to 36 pulses per second of 2 different ion species; thus, 2 pulses of gold might be sent to the synchrotron while 34 pulses of xenon are used locally for 2 separate experiments. Every six seconds, one of the pulses sent to the Bevatron is captured and further accelerated to energies up to 4.9 GeV for protons, .21 GeV/AMU for carbon, or 960 MeV/AMU for uranium Both partially stripped ions (with charge-to-mass ratios as low as that of Au ) and fully stripped ions as heavy as uranium can be accelerated. In addition, the Bevatron's local injector, together with a fast-switching capability, allows nuclear science and biomedical experiments to be conducted concurrently. The Bevalac's major detector facilities include: (1) HISS, a very large volume superconducting magnetic spectrometer system; (2) the Plastic Ball/wall, a highmultiplicity detector with more than 100 detector elements; (3) TASS, a two-arm magnetic spectrometer system; (4) a pion detector system; (5) the Low Energy Beam Line (LEBL), designed for heavy ion experiments in the 40-200 MeV/AMU energy range; (6) a multipurpose projectile-fragment spectrometer; and (7) a magnetically surrounded streamer chamber providing photographs of heavy ion collisions. At the SuperHILAC, a new, on-line isotope separator (OASIS) has characterized many new isotopes, including proton emitters. Acquisition Cost: Estimated replacement cost is $135 million (FY 1984 dollars). Overview of Research Programs Research interests pursued at the Bevalac include: (1) peripheral fragmentation reactions and studies of internal momentum; (2) nuclear reactions induced by beams of radioactive nuclei; (3) central collisions that create extremely hot, dense nuclear matter complexes; (4) production mechanisms of pions, kaons, hyperons, and antiparticles in nuclear matter; (5) searches for new forms of matter such as pion condensates and nuclear isomers; (6) searches for evidence of a quark-gluon plasma; and (7) searches for free quarks. The SuperHILAC research program focuses on: (1) studies in heavy ion collisions of deep-inelastic reactions, fission, the limitations to fusion, and preequilibrium particle emission; (2) band structure and properties of high-spin states; (3) discovery and characterization of new isotopes containing more than 100 protons; and (4) atomic physics of highly charged heavy atoms. Fraction of Beam Time to Outside Users: Program Accomplishments SuperHILAC 50%, Bevalac 50% The Bevalac scientific program has been able to delve deeply into new regions of nuclear equations of state by making high-temperature compressed matter. Measurements have been made of the size of "hot spots" created when heavy nuclei collide. In addition, studies of nuclear collisions in which all (100 or more) secondary charged particles are characterized have revealed the phenomenon of collective energy flow--a phenomenon in which high pressures deflect many particles away from the beam direction. Other studies of central collisions of relativistic heavy ions have uncovered a puzzle in the production of mesons. Pions are produced several times less abundantly than predicted, but kaons are produced several times more copiously than expected. The SuperHILAC has long been a world center for research with very heavy ion beams. The pioneering program in deep-inelastic scattering studies continues with a new generation of particle and gamma-ray detectors and coincidence experiments, and the relationship between the evaporation of particles and fission is also being explored. Electromagnetic moment measurements via Coulomb excitation and Doppler-shift techniques are providing stringent tests of today's nuclear models. Heavy-element isotopes and nuclei near the proton drip line are being studied with new isotope separators. Future Directions Bevalac programs will continue to use their improved detector systems to study correlations in the emissions from hot nuclei; in particular, dilepton emission will be examined. The production of exotic species in hot nuclear matter will be pursued by detecting antiprotons and short-lived rho mesons. Evidence for a transition from ordinary nuclear matter to a quark-gluon plasma will be sought. The SuperHILAC program will continue with increased emphasis on the heaviest projectiles. Explanations for the processes of equilibrating mass, energy, and charge in deep-inelastic reactions will be sought. Further developments in the atomic physics of highly charged heavy ions will be pursued as tests of QED and of relativistic effects. Experimenters are expected to take increasing advantage of the Bevalac's growing flexibility to produce beams of low-charge-state heavy ions, H-like and He-like ions, and unstable nuclei. 88-INCH CYCLOTRON Lawrence Berkeley Laboratory Berkeley, California Description of Facility The 88-Inch Cyclotron is operated as a national facility for experimental research in nuclear science and in applied areas such as biomedicine, surface physics, and radiation damage in semiconductors. The cyclotron can accelerate all ions from hydrogen through krypton to energies above the Coulomb barrier for targets as heavy as uranium. The recent completion of a high-charge-state Electron Cyclotron Resonance (ECR) ion source has greatly extended the available range of ions and energies. This ion source is the first of its type to operate in the United States and presently offers high-charge-state ions at intensities comparable to or exceeding the performance of other ECR sources throughout the world. The maximum energy for heavy ions is 140 MeV q/A, where q and A are the charge and mass of the accelerated ion, respectively. Polarized ions (protons and deuterons) are produced by a high-current atomic beam polarized ion source and are then accelerated to energies as high as 55 MeV. There is a large complement of experimental equipment located in the experimental areas adjacent to the cyclotron. In particular, a new 21-element array of Comptonsuppressed high-resolution germanium detectors has just come into use for studies of nuclei at high spin. There is also a large diameter scattering chamber, high resolution magnetic spectrometer, time-of-flight spectrometer and an on-line isotope separator for the study of exotic nuclei. Acquisition Cost: Estimated replacement cost is $40.5 million (FY 1984 dollars). Overview of Research Program The basic research program is focused in four major areas: (1) investigation of heavy ion reaction mechanisms over a wide range of energies up to 35 MeV per atomic mass unit; (2) production and study of exotic nuclei far from stability; (3) structure of nuclei at high angular momentum; and (4) studies of spin-polarization effects and basic symmetry principles in nuclear interactions. In addition to the above, the cyclotron provides beams for the application of nuclear techniques to other areas of research including biology and medicine and the study of cosmic-ray damage to satellite electronic components. Fraction of Beam Time to Outside Users: Recent Program Accomplishments typically 25-30% Recent research accomplishments include: P: (1) observation of a new radioactive6. decay mode--beta-delayed two proton emission from the exotic nuclei Al and (2) discovery of a giant dipole resonance built on highly deformed, high angular momentum states; (3) observation of nuclei with moments of inertia approaching the rigid-body value; (4) studies of the emission of heavy, complex fragments by highly excited nuclei; (5) the separation of transfer and breakup processes in heavy ion reactions utilizing a very large solid angle plastic scintillator array; and (6) studies of the properties of the transfermium nuclei produced by heavy ion beams and a highly radioactive target of einsteinium. Future Directions Light ion beams will continue to be used for the production and study of new exotic nuclei and for testing fundamental symmetries. Heavy ion beams in the range of 10-35 MeV/AMU will permit an exploration of the transition region from fusion to fragmentation. Studies of the structure of nuclei undergoing rapid rotation will be pushed to spins approaching the fission limit. The development of new beams, including rare isotopes, will be made possible by the ECR source. Use of heavy ion beams for the testing of integrated circuits for susceptibility to cosmic ray damage will be increased to meet a national need in this area. CLINTON P. ANDERSON MESON PHYSICS FACILITY (LAMPF) Los Alamos National Laboratory Los Alamos, New Mexico Description of Facility The LAMPF accelerator is a high-current, 800 million electron volt (MeV), proton linear accelerator about one-half mile in length. The primary proton beam intensity exceeds the sum of intensities of all other proton medium energy and high energy accelerators in the world. It is a source of up to 12 simultaneously operating secondary beams including neutrons, pions, muons, and neutrinos. Polarized and unpolarized beams of protons and neutrons of variable energy are also available. Major, permanent experimental facilities include high resolution proton and (charged and neutral) pion spectrometers. A large NaI detector array is in use to study rare decay modes of the muon and a time-projection chamber is being used to study normal muon decays. Other facilities include capability for isotope production and radiation effects studies. LAMPF also concurrently provides proton beams to the Weapons Neutron Research (WNR) Facility. WNR provides a pulsed spallation neutron source for materials research and for weapons research and development. A proton storage ring funded by Defense Programs and Basic Energy Sciences is under, construction to extend the research capabilities of the WNR Facility by providing higher peak neutron fluxes. Acquisition Cost The original cost was $57 million during the construction period 1967-72. Development costs and subsequent additions, including beam lines, increased the direct outlay to $110 million. Present day replacement cost is estimated at more than $250 million. Overview of Research Program The four nuclear physics research areas of major emphasis at LAMPF are studies of: (1) nuclear structure by observing the interaction of pions with target nuclei; (2) mechanisms by which pions and protons react with nuclei; (3) the basic interaction between protons and protons, between neutrons and protons, and between pions and neutrons or protons; and (4) the fundamental weak interaction. Approximately 60 experiments--resulting in an average of 140 scientific publications--are completed in a typical year. LAMPF serves a large community of outside users with more than 430 scientists each year participating in the research program. Fraction of Beam Time to Outside Users: 650 Program Accomplishments Recent research accomplishments at LAMPF include: (1) use of the pion charge exchange reactions to excite isotopic analóg states, i.e., states of the nucleus showing strong symmetry between neutrons and protons; (2) discovery of an isotopic monopole giant resonance (i.e., neutron-proton breathing mode oscillation); (3) first observation of free muonium; (4) observation of the Lamb shift in muonium; (5) a stringent new limit on the rare decay, muon decaying to 3 electrons, namely |