R.F. Carlson

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.

Inelastic scattering of 46 MeV protons from 12C

Abstract The differential cross sections for the excitation of nine levels of carbon have been measured each at 35 angles from 15° to 150°. The cross sections for the 4.4 and 9.6 MeV levels have a typical relative accuracy of 3%, while the measurements for the 7.7, 10.8, 11.8, 12.7, 14.1, 15.1 and 16.1 MeV levels have a typical accuracy of 10%. The cross sections decrease by from one to three orders of magnitude through the measured angular range. Levels at 13.3 and 16.6 MeV were not observed. The angular distributions have been compared with distorted wave calculations using both macroscopic and microscopic approaches.

A technique for measuring proton total reaction cross sections at medium energies

Abstract Total proton reaction cross sections between 20 and 50 MeV have been measured at the UCLA 50 MeV Cyclotron Laboratory. Our method, a variation of the attenuation technique first proposed by Gooding and Eisberg, is described. Features include a tightly collimated and well defined beam, the ability to use either solid or gaseous targets, and rapid accumulation of the data.