Speaker
Description
Neutron induced reactions can provide significant information in the field of nuclear physics and applications. Hafnium (Hf) is one of the rare-earth isotopes with a relative large total neutron cross-section in the thermal neutron energy region and neutron induced reactions in reactor materials could lead to the production of long-lived isomeric states of Hf isotopes. Thus, the knowledge of neutron cross-sections on Hf isotopes is of great importance both for applications concerning the interaction of neutrons with matter as well as for testing nuclear models.
In this study, experimental cross section measurements for the $^{176}$Hf$(n,2n)^{175}$Hf and $^{174}$Hf$(n,2n)^{173}$Hf reactions were carried out, using the activation technique. The neutron beam energy at 15.3 and 17.1 MeV was produced via the $^{3}$H(d,$n)^{4}$He 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 irradiation was continuous for 28 hours leading to a total neutron fluence of $10^{10}-10^{11}$ n/cm$^{2}$ and a BF3 detector was used for monitoring the neutron flux during the irradiation. After the end of the irradiation, the activity of the Hf target and the Al foils were measured off-line by two HPGe detectors. The $^{176}$Hf$(n,2n)^{175}$Hf reaction has been corrected from the contribution of the $^{177}$Hf$(n,3n)^{175}$Hf and $^{174}$Hf$(n,γ)^{175}$Hf reactions.
Statistical model calculations based on the Hauser-Feshbach theory have also been performed using the code EMPIRE 3.3.2. The predictions have been compared with the data of the present work as well as with data from literature.
