Influence of the Excitation Energy on the Ternary Triton Emission Probability of the 248Cm Fissioning System

An interesting characteristic of the ternary fission process is the influence of the excitation energy (E_exc) on the ternary particle emission probability. Up to now, this effect was studied only for ternary alpha particles (also called Long Range Alpha (LRA) particles), comparing the LRA emission probability (noted LRA/B) for the same compound nucleus at zero excitation energy (E_exc=0, for spontaneous fission) and at an excitation energy equal to the neutron binding energy (E_exc=B_n, for thermal neutron induced fission). It was observed on the three compound nuclei investigated that the increase of the excitation energy leads to an unexpected decrease (by about 20%) of the LRA/B ratio. The aim of the present paper is to study for the first time the influence of the excitation energy on the ternary triton emission probability (noted t/B). This investigation has been carried out on the ²⁴⁸Cm compound nucleus. In a previous measurement, a t/B-value of (1.79±0.11)×10^-4 for ²⁴⁸Cm(sf) was obtained. We report here the determination of the same quantity for ²⁴⁷Cm(n_th,f). The measurement was performed at the high flux reactor of the Laue Langevin Institute in Grenoble (France), where both the energy distributions of the ternary particles (tritons and alpha's) as well as their counting rates could be determined. In particular, a t/B-value of (1.84±0.11)×10^-4 was found, revealing a slight increase of the t/B-value with the excitation energy.