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Nuclear Physics A 775 (2006) 175-187
Determination of the233Pa(n, gamma) capture cross section up to neutron energies of 1 MeV using the transfer reaction 232 ThHe, p234Pa*
S. Boyer1, 2, D. Dassié1, J.N. Wilson3, M. Aïche1, G. Barreau1, S. Czajkowski1, C. Grosjean1, A. Guiral1, B. Haas1, B. Osmanov, G. Aerts2, E. Berthoumieux2, F. Gunsing2, C. Theisn2, N. Thiollière2, 4, L. Perrot2, 5

The γ-ray emission probability distribution of 234Pa* has been measured between 5.2 and 6.2 MeV excitation energy using the transfer reaction 232Th(3He, p)234Pa* at an incident 3He energy of 24 MeV. The experimental set-up is made of four liquid scintillator C6D6 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 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, γ) capture cross section of 233Pa, in the neutron energy range 0 to 1 MeV, has been deduced via the product of the measured γ emission probability of 234Pa* with the calculated compound nucleus formation cross section of the reaction 233Pa + n. A comparison between existing data bases or recent predictions and the present results is also made.
1 :  CENBG - Centre d'Etudes Nucléaires de Bordeaux Gradignan
2 :  DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
3 :  IPNO - Institut de Physique Nucléaire d'Orsay
4 :  LPSC - Laboratoire de Physique Subatomique et de Cosmologie
5 :  GANIL - Grand Accélérateur National d'Ions Lourds
Physique/Physique Nucléaire Expérimentale
Nuclear reactions – 232Th(3He – p) – E=24 MeV – measured – Eγ – Iγ – (charged particle) γ-coin – 234Pa deduced – γ-ray emission probability – 233Pa(n – γ) – E=100–900 keV – deduced – capture σ – Comparison with model predictions