Dependence of the ROT effect on the energy of different light charged particles and on the incident neutron energy

Irina Guseva,Yuri Gusev,Alexei Gagarski,Friedrich Gönnenwein,N Carjan,S Oberstedt

doi:10.1051/epjconf/202125600006

Irina Guseva, Yuri Gusev + Show 4 more

Open Access

https://doi.org/10.1051/epjconf/202125600006

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Abstract

The shift of the angular distribution of different light charged particles in ternary fission of235U induced by polarized neutrons, the so-called ROT effect, was estimated by modified trajectory calculations, which take into account the rotation of the compound nucleus. In previous publications onlyα-particles were considered. It is shown here that inclusion of tritons significantly improves the agreement of the energy dependence of the ROT effect with experiment while the inclusion of5He particles practically does not influence this dependence. In particular, the change in the magnitude of the ROT effect depending on the energy of incident neutrons is correctly predicted. Also, the ROT effect for gamma quanta and neutrons in binary fission is discussed along the same lines, because all mentioned effects are proportional to the effective angular velocity of the compound nucleus at the moment of scission.

Highlights

The ROT e↵ect was discovered in 2005. It corresponds to a shift of the angular distribution of light charged particles (LCP), mainly alphas, which was observed in ternary fission of 235U induced by cold polarized neutrons [1, 2]
We assume that the ROT e↵ect mostly develops after the nucleus rupture and when nuclear forces have already ceased to influence the trajectories of fission fragments (FFs) and LCPs flying apart
In the case of correctly fitted initial parameters of the considered system, the calculated final distributions for fission fragments and light charge particles should coincide with those that were experimentally recorded for a non-rotating fission system, in our case for ternary fission induced by unpolarized neutrons

Summary

Introduction

The ROT e↵ect was discovered in 2005 It corresponds to a shift of the angular distribution of light charged particles (LCP), mainly alphas, which was observed in ternary fission of 235U induced by cold polarized neutrons [1, 2]. It was assumed that this experimentally detected shift of the angular distribution is associated with the presence of rotational states in the level structure of the deformed compound nucleus. The validity of this hypothesis was confirmed by Monte-Carlo calculations [3, 4]. Flipping the spin of the polarized neutron beam inducing fission leads to opposite shifts ∆ and −∆ of the LCP angular distribution, which allows to detect the ROT e↵ect. The di↵erence in angular distributions of LCP for the two spin orientations is 2∆

Experimental technique and data analysis

Vt V ij ij ij

Results of calculations

Dependence of the ROT effect on the incident neutron energy

Summary and outlook