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 gamma-ray emission probability distribution of Pa-234* has been measured between 5.2 and 6.2 MeV excitation energy using the transfer reaction Th-232(He-3,p)Pa-234* at an incident He-3 energy of 24 MeV. The experimental set-up is made of four liquid scintillator C6D6 detectors and four Si telescopes arranged to detect gamma rays and charged particles in coincidence. In order to determine the total number of gamma-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 C6D6 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, gamma) capture cross section of Pa-233, in the neutron energy range 0 to 1 MeV, has been deduced via the product of the measured gamma emission probability of Pa-234* with the calculated compound nucleus formation cross section of the reaction Pa-233 + n. A comparison between existing data bases or recent predictions and the present results is also made. (c) 2006 Elsevier B.V. All rights reserved.