Research in Intermediate Energy Physics

点击翻译按钮获取中文摘要

New problems of basic interest in nuclear and particle physics at intermediate energies will be studied. The initial emphasis in the program will be on a precise measurement, with ~0.5 percent accuracy, of the rate of decay of charged pions. This process provides the theoretically most unambiguous means to study weak u-d quark mixing which directly tests quark- lepton universality and can thus constrain certain aspects of physics beyond the present Standard Model. The proposed experiment represents a first step in a staged effort at improving the present 4 percent accuracy of the pion beta decay rate, to approach and eventually surpass that of pure Fermi nuclear beta decays (now ~0.2 percent). At the level of accuracy proposed for the first step, our measurement will provide the most sensitive test of the CVC hypothesis in a meson. A large-solid-angle detector will detect decays at rest and will also be sensitive to other rare pion decays. Initial runs have been approved for 1989 at PSI, and detector development work is presently under way at University of Virginia. Other experimental commitments include a precise measurement of the muon momentum in pion decay at rest at PSI, a measurement of the spin-dependent structure functions of the neutron and proton in the scaling region at CERN, and work related to future experiments at CEBAF.