Excitation of the ground state rotational band inNe20by 0.8 GeV protons

Abstract

Angular distributions for the scattering of 0.8 GeV polarized protons from the ground state rotational band in $^{20}\mathrm{Ne}$ are reported. Cross sections and analyzing powers for protons exciting these states were measured with a high resolution spectrometer. Coupled channels and distorted wave Born approximation analyses of scattering data for the ${0}^{+}$, ${2}^{+}$, ${4}^{+}$, and experimentally unresolved ${6}^{+}$ states are presented. The observed cross section data for the ${0}^{+}$, ${2}^{+}$, and ${4}^{+}$ states are reproduced quite well with the coupled channels calculations, and the large hexadecapole deformation reported previously is confirmed. The distorted wave Born approximation results are equally good for the ${0}^{+}$ angular distribution, but are a significantly poorer representation of the cross section data for the ${2}^{+}$ and ${4}^{+}$ states. Both calculations do equally well in explaining the ${0}^{+}$ analyzing power data and both fail to explain the ${4}^{+}$ analyzing power data past the region of the first maximum. The coupled channels results do a better job in explaining the ${2}^{+}$ analyzing power data. The multipole moments of the deformed optical potential used in the coupled channels calculations are related to those of the matter distributions by Satchler's theorem. These are compared to the moments found using other hadronic probes, those of the charge distribution determined by electromagnetic measurements, and to moments from shell model and Hartree-Fock calculations.