An investigation of the 40Ca(p, 2p) reaction with polarised protons
Abstract
The reaction has been observed at the TRIUMF facility using a 200 MeV polarised proton beam. Data were acquired at fourteen independent pairs of angles for separation energies from 0 to 100 MeV over a wide range of recoil momenta. Cross sections and analysing powers for the valence states were extracted from the data.
The results are compared with distorted wave impulse approximation (DWIA) calculations which incorporated the wave functions of EIton and Swift, spin-orbit dependent optical model potentials from Schwandt, and a half-off-shell prescription for the p-p scattering matrix element. The l = 2 states show strong j-dependence in the analysing power at most measured angles. DWIA calculations agree well with the analysing powers for equal and near equal angles in the forward direction. Unless nonlocality effects are included, however, the cross sections are overestimated (typically by 80%) when spectroscopic factors equal to the shell-model values of (2J + 1) are used. The analysing power for the state for small recoil momentum is reasonably predicted whether spin-orbit dependence in the optical model is included or not.
For some kinematic conditions, peaks in the separation energy spectrum suggest the possible presence of 40Ca single particle states at ∼12 MeV and ∼22 MeV excitation respectively.
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- •
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- •
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- •
- γ-ray mixing ratios σ,
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- •
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Present address: Institute de Physique, Université de Neuchâtel, Rue A.-L. Breguet 1, CH-2000, Neuchâtel, Switzerland.