Cross Section Measurements and Theoretical Study of the ^174,176Hf(n,2n)^173,175Hf Reactions

Abstract

Experimental cross section measurements for the 176Hf(n,2n)175Hf and 174Hf(n,2n)173Hf reactions were carried out, using the activation technique. The neutron beam energy in the range of 15.3-20.3 MeV was produced via the 3H(d,n)4He reaction at the 5.5 MeV Tandem Van de Graaf accelerator laboratory of NCSR “Demokritos”. A thin metallic foil of natural Hf was used, while for the determination of the neutron flux at the target position, reference foils of Al were placed at the front and back of the Hf target. The irradiations were continuous for ~24-48 hours, leading to a total neutron fluence of 1010-1011 n/cm2 and a BF3 detector was used for monitoring the neutron flux during the irradiations. After the end of each irradiation, the activity of the Hf target and the Al reference foils were measured off-line by two HPGe detectors. The 176Hf(n,2n)175Hf reaction has been corrected for the contribution of the 177Hf(n,3n)175Hf and 174Hf(n,γ)175Hf reactions. Statistical model calculations based on the Hauser-Feshbach theory have also been performed using the EMPIRE 3.2.3 code. The predictions have been compared with the data of the present work as well as with data from literature.