EPICS and HRS

Work at HRS and EPICS is summarized. A longitudinally (L) polarized target was mounted at HRS during cycle 41. Capable of polarizing both protons and deuterons, it was used to study few-nucleon interactions at forward-scattering angles into the Coulomb-nuclear interference region. At EPICS near the beginning of the summer 1984 production period, the spectrometer front wire chamber was replaced with a new chamber having only half the number of planes (two each, x and y), capable of resolving the left-right ambiguity by means of the induced cathode pulse. Reducing the number of planes and filling the inactive layers in the chamber assembly with helium resulted in halving the material thickness and improving the missing-mass resolution from 140 to 100 keV FWHM at 180 MeV. One also notes that resolution was correlated with vertical (dispersion plane) scattering angle and that it is even better for negative angles than for positive angles. With reduced acceptance, resolution of 80 keV can be obtained. The Data-Analysis Center (DAC) VAX computer spooling and replay capability was completed for the EPICS and HRS RSX-11M and -11D data tapes. New 6250-bpi tape drives and larger system buffers on the HRS computers have tripled tape capacity and doubled the rate. A similar change will be made to EPICS. The EPICS PDP-11/45 was replaced by a VAX-11/730 at the beginning of cycle 40 with very few difficulties. The VMS operating system user interface was similar enough to that available under RSX-11M that users familiar with the old system adapted quite well