Differential cross sections and polarizations in elastic p-d scattering at medium energies

Abstract

Differential cross sections for p-d elastic scattering have been measured at 22.0, 35.0 and 46.3 MeV using the energy-analysed external proton beam of the UCLA sector-focussed cyclotron. The angular distributions cover centre-of-mass angles between 9° and 168°. At forward angles both protons and deuterons were observed using a d E/d x- E telescope counter consisting of a fully depleted surface-barrier detector ( ΔE) and a NaI(Tl) scintillation detector. ( E). At larger angles, protons were observed using an array of four NaI(Tl) scintillation detectors. The differential cross sections have in general a relative uncertainty less than 2%, while the absolute scale of the measurements has an uncertainty of 1.7%. The proton polarization angular distributions at 35.0 and 40.0 MeV were also measured. In this part of the experiment, the polarized proton beam facility was used. The polarized proton beam was obtained by scattering the internal beam of the cyclotron from a carbon scatterer. At 35.0 MeV, the polarization angular distribution covers centre-of-mass angles between 20° and 164°. At 40.0 MeV, measurements were made for centre-of-mass angles greater than 130° only. Scattered particles were observed using six NaI(Tl) scintillation detectors placed in groups of three on either side of the incident beam. The target used when detecting elastically scattered protons was deuterium gas. The backward part of the angular distribution was measured by detecting recoil deuterons from a deuterated polythylene target. The available proton polarization data for p-d elastic scattering have been used to construct a polarization contour diagram for the energy range of 10–400 MeV.