Degradation of silicon detectors under long-term irradiation by 252Cf fission products

The response function of the recoil nuclei in detectors designed for detection of neutrinos or dark matter particles can be determined only through usage of a neutron source with a known energy spectrum. A possible solution for a compact neutron calibration source is a combination of a 252Cf neutron source and a semiconductor detector that detects fission fragments, and thus records the neutron emission moment. This work is devoted to the degradation study of the operating parameters for silicon semiconductor detectors irradiated by fission fragments of the nuclide of 252 Cf. Two types of Si detectors were under investigations - silicon-lithium Si(Li) p-i-n detectors and silicon surface barrier detectors. As a result of the measurements, the maximum permissible radiation doses for the correct operation of both types of detectors and the relation of the received radiation dose to the spectroscopic characteristics of the detectors were determined.

Enhanced Fission Probability of Even-Z Fragments in the Decay of Hot and Rotating 210Rn* Compound System

Mass and charge distribution of the cross-section for the fission fragments obtained in the decay of hot and rotating compound system formed in the reaction 48Ca + 162Dy → 210Rn* at an incident energy 139.6 MeV has been calculated using the dynamical cluster-decay model. Isotopic composition for each element belonging to the symmetric mass region has been obtained. The shell closure at N=50 for light and at Z=50 for heavy mass binary fragments gives a deep minima in the fragmentation potential at touching configuration and governs the fission partition of the compound system. The fission fragments of the symmetric mass region have their dominating presence along with strong odd-even staggering i.e., even-Z fission fragments are more probable than the odd ones, similar to the observed trends of the yield.

Transformations of actinides fission product yields due to post scission emission of nuclear particles:232Th

The "many ensembles" method was proposed to investigate the influence of nuclear particles' post-scission emission on mass and charge distributions of fission products. The post scission approximation had been used; each of these ensembles consists of the fission fragments after emission of chains of different lengths, both the beta (±β) particles and neutrons. The theory allows one to find the most probable two fragment clusters of fission products and study their evolution after the post-scission emission of nuclear particles. The isotope ²³²Th was chosen as an example, the fission fragments of which are intensively studied in the experiment. It is shown that the post-scission emission of nuclear particles eventually leads to the convergence of the asymmetric peaks, which looks like enhanced symmetric fission mode over asymmetric one for fission product yields. A comparison of the theoretical results and experimental data for the ²³²Th fission fragments indicates their satisfactory matching.