Study of α-particles produced in thermal neutron induced reactions on 235U

The 235U(nsub(th), α) reaction and the α-particles emitted in the thermal neutron induced fission of 235U were measured using a very pure thermal neutron beam of the Grenoble high flux reactor. An upper limit of 0.66 mb was determined for the 235U(nsub(th), α) reaction cross section, which is lower than all the previous results. The energy distribution of the α-particles produced by the 235U(nsub(th), f) reaction was measured down to 7 MeV with a non-shielded surface-barrier detector telescope assembly. The measured distribution has a quasi-Gaussian shape; it reveals, however, a pronounced deviation from such a shape at lower α-energies. Several possible explanations for this deviation are discussed. (Auth.)