High Resolution Spectroscopy in the Third Minimum of 232Pa

Abstract

The fission probability of 232Pa was measured as a function of the excitation energy in order to search for hyperdeformed (HD) transmission resonances using the (d,pf) transfer reaction on a radioactive 231Pa target. The experiment was performed at the Tandem accelerator of the Maier–Leibnitz Laboratory (MLL) at Garching using the 231Pa (d,pf) reaction at a bombarding energy of E_d = 12MeV and with an energy resolution of Delta(E) = 5:5 keV. Two groups of transmission resonances have been observed at excitation energies of E* = 5:7 and 5.9MeV. The fine structure of the resonance group at E* = 5:7MeV could be interpreted as overlapping rotational bands with a rotational parameter characteristic to a HD nuclear shape (hbar^2 / 2theta = 2:05 keV). The fission barrier parameters of 232Pa have been determined by fitting TALYS nuclear reaction code calculations to the overall structure of the fission probability.