Excitation functions of some neutron threshold reactions on isotopes of molybdenum

Abstract

Cross sections were measured for (n,p) reactions on 92, 95, 96, 97, 98mo, (n, α) reactions on 92, 98Mo, and (n, 2n) reaction on 100Mo for the first time in the neutron energy range of 5.9 to 9.6 MeV. The quasi-monoenergetic neutrons were produced via the 2H(d, n) 3He reaction using a deuterium gas target at a compact cyclotron. Use was made of the activation technique in combination with high-resolution γ-ray spectroscopy. Some systematic trends observed in the excitation functions are discussed. For the various isotopes of molybdenum, with increasing mass of the target nucleus, the thresholds of (n,p) and (n,α) reactions increase and the magnitudes of cross sections near the maxima of the excitation functions appear to decrease. Hauser-Feshbach calculations show that in general the excitation functions of (n, p) and (n, α) reactions are described within a factor of 2 by the statistical model only up to about 8 MeV; the (n,2n) reaction on 100Mo, however, is reproduced well from threshold up to 15 MeV by this model.