Speaker
Description
In [1], it was rightly noted that “nuclear fission remains the most complex topic in applied nuclear physics”. The current state of the theory based on the model of transition states at fission barriers does not allow one to reproduce the fission cross section of a nucleus by neutrons as a function of their energy without using a significant number of fitting parameters. This is partly due to the lack of information about the spectra of transition states. In our opinion [2,3], the understanding of the fission mechanism can be improved by using data on the angular distribution of fragments or, in other words, on the ratio of the differential fission cross section to the total one. The idea is that the angular distribution of fragments is determined by the distribution of the fission probability over the projection K of the nuclear spin on the axis of deformation on a barrier, which in turn depends on what values of K characterize the rotational bands of transition states on the barrier. Thus, the angular distribution of fragments can provide important information about the spectrum of transition states.
Previously, we analyzed data on fission cross sections and angular distributions of fission fragments in the reactions 237Np(n,f) [3] and 240Pu(n,f) [2]. The present work is devoted to the reaction of 236U(n,f). The parameters of the fission barriers taken from [1] were slightly changed, which made it possible to reproduce, using the TALYS-1.9 program [4], the energy dependence of the total fission cross section in the range of incident neutron energy from 0.5 to 120 MeV. Using a modified version of the same program gives a good description of the angular anisotropy W(0º)/W(90º) of the fission fragments within the statistical model of the probability distribution of fission over the number K in a wide range from 2.5 to 300 MeV. Of particular interest is the low-energy region from 0.5 to 2.5 MeV, in which the energy behavior of angular anisotropy may be related to the structure of the transition state spectrum at the 237U fission barrier.
- R. Capote et al. Nucl. Data Sheets 110, 3107 (2009).
- A. S. Vorobyev et al., JETP Lett. 112, 323 (2020).
- A. L. Barabanov et al.. EPJ Web Conf. 256, 00003 (2021).
- A. J. Koning, S. Hilaire, M. C. Duijvestijn. Proc. Int. Conf. on Nuclear Data for Science and Technology (2007, Nice, France); EDP Sciences. 2008. P.211.
| The speaker is a student or young scientist | No |
|---|---|
| Section | 2. Experimental and theoretical studies of nuclear reactions |
