Determination of the 233Pa(n, γ) capture cross section up to neutron energies of 1 MeV using the transfer reaction 232Th(3He, p)234Pa∗

The γ -ray emission probability distribution of 234 Pa ∗ has been measured between 5.2 and 6.2 MeV excitation energy using the transfer reaction 232 Th( 3 He, p) 234 Pa ∗ at an incident 3 He energy of 24 MeV. The experimental set-up is made of four liquid scintillator C 6 D 6 detectors and four Si telescopes arranged to detect γ rays and charged particles in coincidence. In order to determine the total number of γ -ray cascades in a given nucleus, the raw experimental detected gamma-ray events have to be corrected by the weighting function technique. This weighting requires complete knowledge of the efficiency and response functions for the C 6 D 6 detector set-up and surroundings. These have been determined experimentally using gamma-ray sources, inelastic scattering reactions and transfer reactions on light nuclei. Simulations which reproduce successfully the detector response and efficiency are presented. From these measurements, the (n, γ ) capture cross section of 233 Pa, in the neutron energy range 0 to 1 MeV, has been deduced via the product of the measured γ emission probability of 234 Pa ∗ with the calculated compound nucleus formation cross section of the reaction 233 Pa + n. A comparison between existing data bases or recent predictions and the present results is also made.