Measurements of the T-odd effects in fission of 235U at the FRM-2 reactor

The T-odd effects in fission were discovered in experiments on ternary fission with cold polarized neutrons performed at the ILL (Grenoble). The first effect was named TRI-effect, as it imitates the violation of the time reversal invariance. The second one was called ROT-effect, as it appears due to rotation of a nucleus after capturing the polarized neutron. Both effects, being formally T-odd, currently are not considered as violating the time reversal invariance, and are explained by the complicated mechanism of the fission process. However, by measuring these effects one can obtain unique information about the contributions of the quantum numbers J and K, which characterize the fission channels, introduced by A. Bohr.

A series of experiments has been performed at the FRM II reactor – at the MEPHISTO facility, where the ROT-effect in the emission of prompt γ-rays and neutrons in binary fission of 235U and 233U induced by cold polarized neutrons was observed, and at the POLI instrument, where the ROT effect for 235U was measured for the first time in the lowest resonance 0.3 eV.

The results of recent experiments and future prospects of the project will be presented.