Physics division annual report 1999

This report summarizes the research performed in the past year in the Argonne Physics Division. The Division's programs include operation of ATLAS as a national heavy-ion user facility, nuclear structure and reaction research with beams of heavy ions, accelerator research and development especially in superconducting radio frequency technology, nuclear theory and medium energy nuclear physics. The Division took significant strides forward in its science and its initiatives for the future in the past year. Major progress was made in developing the concept and the technology for the future advanced facility of beams of short-lived nuclei, the Rare Isotope Accelerator. The scientific program capitalized on important instrumentation initiatives with key advances in nuclear science. In 1999, the nuclear science community adopted the Argonne concept for a multi-beam superconducting linear accelerator driver as the design of choice for the next major facility in the field a Rare Isotope Accelerator (WA) as recommended by the Nuclear Science Advisory Committee's 1996 Long Range Plan. Argonne has made significant RD QCD calculations based on the Dyson-Schwinger approach which were extended to baryon systems and finite temperatures and densities; the structure of heavy nuclei; and proton decay modes of nuclei far from stability. The medium-energy program continues to focus on new techniques to understand how the quark-gluon structure of matter impacts the structure of nuclei. The HERMES experiment began making measurements of the fraction of the spin of the nucleon carried by the glue. Drell-Yan experiments study the flavor composition of the sea of the proton. Experiments at Jefferson lab search for clues of QCD dynamics at the hadronic level. A major advance in trace isotope analysis was realized with pioneering work on Atom Trap Trace Analysis, exploiting the exquisitely sensitive nature of laser-atom traps to detect background free, {sup 81}Kr at the 10{sup -13} level. This technique provides a valuable new approach to such diverse problems as dating old ground water, the solar neutrino problem, measuring charge radii of exotic nuclei and medical applications.« less