Nuclear Science and Engineering / Volume 169 / Number 2 / October 2011 / Pages 188-197
Measurements of (n, 2n) reaction cross sections to produce 84Rb, 86Rb, 88Y, 139Ce, 141Ce, 168Tm, 174m+gLu, 180mTa, 184m+gRe, 196n+gAu, and 237U were carried out in the range of 13.4 to 14.8 MeV. The samples were irradiated at various positions on the surface of a two-ring orientation instrument with a 20-cm radius centered at the deuterium-tritium neutron source. The 27Al(n,)24Na reaction was used to monitor the neutron fluence in the target samples. The neutron energies of different directions were determined using the ratio of 89Zr to 92mNb specific activities induced in Zr and Nb foils by (n, 2n) reactions. The (n, 2n) products were measured using a calibrated Ge detector. Experimental uncertainty was within ±4%. The results are presented and compared with the results of references and ENDF/B-VII.0 evaluations. Cross sections of 85Rb(n, 2n)84Rb, 140Ce(n, 2n)139Ce, and 89Y(n, 2n)88Y were in good agreement with those of ENDF/B-VII.0 evaluations; however, disagreements were observed for 175Lu(n, 2n)174Lu and 142Ce(n, 2n)141Ce between the present data and the ENDF/B-VII.0 evaluation file. The present data showed improvement in accuracy in comparison with previously reported data; therefore, the results should be offered for evaluations of neutron (n, 2n) cross sections.