Spin dependent total cross-section measurements Deltasigma_L, Deltasigma_T, in P-P scattering between 200 and 520 MeV

Abstract

The differences Deltasigma_L (Deltasigma_T) between proton-proton total cross sections for longitudinal (transverse) spin states parallel and antiparallel to the incident beam momentum have been measured at the TRIUMF laboratory from 200 to 520 MeV.

A beamline was designed to produce a transverse or longitudinal polarization from the vertically polarized beam extracted from the cyclotron. The polarization of the beam was measured using a polarimeter which had been previously calibrated to +/-1.5%. The polarization of the dynamically polarized butanol target was monitored by an NMR system under microprocessor control. In addition, multiwire proportional chambers detected elastically scattered protons and enabled an independent value of the target polarization to be calculated. Careful attention was paid to the removal of systematic effects by talcing data with different combinations of beam and target polarizations. The beam transmitted through the target was detected by six closely spaced circular scintillation counters. The transmission ratios were corrected for Coulomb-Barrier and Coulomb-Nuclear interference effects before final total cross sections were evaluated.

Values of Deltasigma_L (Deltasigma_T) were measured at six (seven) energies. At the two lowest energies (203 and 325 MeV), where inelasticity is zero or negligible, excellent agreement was obtained with phase shift predictions. The results were incorporated into a phase shift analysis.