Proton capture to continuum states ofBi209

Abstract

High resolution spectra from fast proton radiative capture in $^{208}\mathrm{Pb}$ are presented for three energies of the incident protons: 14.8, 15.7, and 16.9 MeV. The collected spectra were analyzed with emphasis on the region of capture to unbound states in order to search for possible structure and to study the competition between two basically different phenomena: the statistical process versus the fluctuation effects in radiative capture to unbound final states. In the energy region of incoming protons considered in our experiment, the statistical processes modeled with a Hauser-Feshbach calculation dominate. The spectra of primary \ensuremath{\gamma} rays, coincident with the low energy one from the decay of the ${f}_{7/2}$ single-particle state, show a prominent structure which is predominantly of ${g}_{9/2}$ character. The calculations of continuum spectra based on the extended direct-semidirect model and the Hauser-Feshbach statistical approach successfully reproduce the experimental data.