Quasi-elastic Scattering of Polarized Protons from Calcium-40 at 200 MeV PDF Download

Author: Larry Edward Antonuk
Publisher:
ISBN:
Category : Calcium
Languages : en
Pages : 0

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Book Description
A [superscript 40]Ca(p[superscript +], 2p) experiment was performed at the TRIUMF facility using a 200 MeV polarized proton beam. Data were acquired at eleven independent pairs of angles for separation energies from 0 to 100 MeV over a wide range of recoil momenta. For eight angle pairs, cross sections and analysing powers were extracted from the data as a function of the energy difference of the final state protons for knockout from the valence states (1d[subscript 3/2], 2s[subscript 1/2], and 1d[subscript 5/2]). Cross section and analysing power information was obtained for 3 other angle pairs for only the 2s[subscript 1/2] state. The results were compared with Distorted Wave Impulse Approximation (DWIA) calculations which incorporated the bound state wave functions of Elton and Swift (EL-67), an optical model potential, with spin-orbit terms, from Schwandt (SC-80), and a half-off-shell prescription for the free p-p scattering matrix element. The l=2 states show strong j-dependence in the analysing power at most measured angles. Such dependence was predicted by Jacob and Maris (JA-73) and has been observed for l=1 states in [superscript 16]O (KI-80, KI-76). DWIA calculations agree well with the present analysing powers for equal and near equal angles in the forward direction. The spectroscopic factors resulting from normalizing the calculations to the data are only ~50% to ~55% of the shell model values of (2J+1). This is significantly lower than spectroscopic factors resulting from other reactions. Generally, the kinematic regions of better agreement between the analysing power data and calculations are similar to those of the earlier [superscript 16]O(p[superscript +], 2p) experiment. The analysing power for the 2s[subscript 1/2] state near l=0 dominance is reasonably predicted whether spin-orbit dependence in the optical model is included or not. At various kinematic conditions, peaks in the cross section suggest the possible presence of 1p[subscript 1/2] and 1p[subscript 3/2] [superscript 40]Ca single particle states at ~21 MeV and ~30 MeV separation energy respectively.