Experimental determination of the proton escape width in the giant dipole resonance ofY89

Abstract

The $^{89}\mathrm{Y}$($\ensuremath{\gamma}$,$p$)$^{88}\mathrm{Sr}$ reaction was studied at various bremsstrahlung end point energies in the giant dipole resonance region. Using an artificially constructed pseudomonoenergetic photon spectrum, it was possible to determine the absolute cross sections for various photoproton reaction channels. From the direct decay cross sections the proton escape width ${\ensuremath{\Gamma}}_{p}^{\ensuremath{\uparrow}}$ of the ${T}_{l}$ giant dipole resonance was derived; its value amounts to 0.30-0.35 MeV. The nondirect contribution equals about 25% of the total energy-integrated photoproton cross section.