Decay via proton emission of isobaric analog states (IAS's) in $^{ 91}{ Nb}$ was studied using the $^{ 90}{ Zr}(\alpha,t)$ reaction at $E_\alpha$=180 MeV. This study provides information about the damping mechanism of these states. Decay to the ground state and low-lying phonon states in $^{ 90}{ Zr}$ was observed. The experimental data are compared with theoretical predictions wherein the IAS `single-particle' proton escape widths are calculated in a continuum RPA approach. The branching ratios for decay to the phonon states are explained using a simple model.
Categories: nucl-ex