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Hadrons and Nuclei

Eur. Phys. J. A 9, 385-396

Production of neutron-rich isotopes in fission of uranium induced by neutrons of 20 MeV average energy

G. Lhersonneau1,2 - P. Dendooven1 - G. Canchel1 - J. Huikari1 - P. Jardin3 - A. Jokinen1 - V. Kolhinen1 - C. Lau4 - L. Lebreton2 - A.C. Mueller4 - A. Nieminen1 - S. Nummela1 - H. Penttilä1 - K. Peräjärvi1 - Z. Radivojevic1 - V. Rubchenya1 - M.-G. Saint-Laurent3 - W.H. Trzaska1 - D. Vakhtin5 - J. Vervier2 - A.C.C. Villari3 - J.C. Wang1 - J. Äystö1

1 Department of Physics, University of Jyväskylä, POB 35, 40351-Jyväskylä, Finland
2 Centre de Recherches du Cyclotron, 2 chemin du cyclotron, B-1348-Louvain-La-Neuve, Belgium
3 GANIL, BP 5027, F-14076 Caen, France
4 Institut de Physique Nucléaire, F-91406 Orsay, France
5 Khlopin Radium Institute, St. Peterburg, Russia

Received: 10 July 2000
Communicated by C. Signorini

Abstract
In the context of a parameter study conducted by several laboratories for future European radioactive beam facilities based on fast-neutron induced fission, in particular for the SPIRAL-II project at GANIL, we have measured the yields of neutron-rich isotopes in the mass range of 88 to 144. These nuclei were obtained as fission products of natural uranium bombarded by neutrons of 20 MeV average energy emitted by a thick carbon target irradiated by 50 MeV deuterons. Yields have been measured using on-line mass separation with the ion-guide method. Compared with proton-induced fission at 25 MeV the magnitude of cross-sections, except for the symmetric region, is similar. Z-distributions of isobars have the same width, 0.7 charge units, but their maxima are shifted by about 0.8 charge units, favouring production of the neutron-richer isobars. Our data allow calculations of absolute cross-sections for fission of natural uranium induced by neutrons of about 20 MeV.

PACS
24.75.+i General properties of fission - 25.85.Ec Neutron-induced fisssion - 25.85.Ge Charged-particle induced fission


Copyright Società Italiana di Fisica, Springer-Verlag 2000