Measurements of (n, 2n) Reaction Cross Sections at 14 MeV for Several Nuclei

Measurements of (n, 2n) reaction cross sections to produce Rb-84, Rb-86, Y-88, Ce-139, Ce-141, Tm-168, Lu174m+g, Ta-180m, Re184m+g, Au196n+g, and U-237 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 Al-27(n, alpha)Na-24 reaction was used to monitor the neutron fluence in the target samples. The neutron energies of different directions were determined using the ratio of Zr-89 to Nb-92m 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 Rb-85(n, 2n)Rb-84, Ce-140(n, 2n)Ce-139, and Y-89(n, 2n)Y-88 were in good agreement with those of ENDF/B-VII.0 evaluations; however, disagreements were observed for Lu-175(n, 2n)Lu-174 and Ce-142(n, 2n)Ce-141 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.