Isobaric Analog Resonances from Proton Scattering on the Barium Isotopes

Abstract

With barium isotopes of mass 130, 132, 134, 136, and 138 as targets, proton elastic scattering excitation functions have been obtained at several angles. In the proton energy range 7.0-12.0 MeV, we observed several resonances which correspond to isobaric analogs of the low-lying states of the target-plus-neutron systems. The resonance data have been analyzed to extract proton elastic widths, total widths, and resonance energies. Spectroscopic factors have been extracted by comparing the measured proton elastic widths with the single-particle widths calculated on the basis of a shell-model description of the analog state. The spectroscopic factors so determined are compared with those from the $\mathrm{Ba}(d,p)$ reaction to the parent analog states. The variation of single-particle width with the parameters of the bound-state neutron well has been investigated. From the analog resonance energies and the $Q$ values for the parent states in $\mathrm{Ba}(d,p)$ reactions, the Coulomb shifts of the principal resonances have been found.