Experiments on the nuclear interactions of pions and electrons. Progress report

Abstract

We have completed the analysis of the /sup 3/He(/pi//sup +/,pp)n reaction, and are working on the analysis of data for the /sup 3/He(/pi//sup /minus//,pn)p reaction. An experiment to study the /pi/ + d /yields/ 2p reaction at LAMPF was successful in studying incident pion energies as low as 6 MeV. Preliminary results have been reported, and work is continuing to improve the accuracy in the calculation of the fraction of pions in the incident beam. A proposal has been accepted by LAMPF for a new experiment, scheduled to run in the summer of 1990, to study pion absorption in /sup 3/He and /sup 4/He using an extensive scintillator time-of-flight system capable of detecting neutrons as well as charged particles. We are continuing to analyze data obtained in PSI in the search for the admixture of massive neutrinos in pion decay and have continued the search for fractionally charged particles. We are also fully involved in some major collaborations: the search for the decay /mu//sup +/ /yields/ e/sup +/ + /gamma/, and the study of anti-proton absorption in heavy nuclei. We are taking part in a U.Va.-PSI collaboration to measure pion beta decay to an accuracy of about 1%, using amore » large acceptance CsI detector to measure the /pi//sup 0/ following decay of stopped /pi//sup +/ mesons. We have also been working on experiments to study electron scattering, using the SLAC-NPAS facility for nuclear physics and the electron accelerator at SACLAY in France. Data from experiment NE-9 at SLAC are being analyzed. This experiment, which was run near the end of 1987, is intended to separate the transverse and longitudinal cross sections for inclusive electron scattering in the QFS region. Experiment NE-8 measured the cross section for photo-disintegration of the deuteron in the GeV range. Some design work was carried out this year on Experiment NE-16 at SLAC, a study of the (e,e'p) reaction in /sup 4/He, expected to run late in 1990.« less