Excitation functions of 93Nb(n, 2n) 92mNb, 93Nb(n, α) 90m,gY, 139La(n, α) 136Cs and 181Ta(n, p) 181Hf reactions in the energy range of 12.5–19.6 MeV

Abstract

Cross sections were measured for the 93Nb(n, 2n) 92mNb, 93Nb(n, α) 90m,gY, 139La(n, α) 136Cs and 181Ta(n, p) 181Hf reactions in the energy range of 12.5–19.6 MeV. Use was made of the activation technique in combination with high-resolution γ-ray spectroscopy, except for the product 90gY where radiochemical separation and β − counting were applied. The neutron fluence rates were determined using two independent methods, viz. proton recoil telescope and 27Al(n, α) 24Na monitor reaction. An appraisal of the available cross section data for the five investigated processes was carried out. Due to its relatively high importance as a dosimetry reaction an evaluation of the 93Nb(n, 2n) 92mNb excitation function based on the most recent data is recommended. For the other reactions our measurements furnish an extended data base. A comparison of the experimental data with values calculated from the semi-empirical code THRESH is presented. The code predicts unknown activation cross sections only with partial success.