<Emphasis Type="Italic">T</Emphasis>-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons |
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Authors: | G V Danilyan J Klenke V A Krakhotin Yu N Kopach V V Novitsky V S Pavlov P B Shatalov |
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Institution: | 1.Institute for Theoretical and Experimental Physics,Moscow,Russia;2.Forschungs-Neutronenquelle Heinz Meier-Leibnitz (FRM II),Garching,Germany;3.Frank Laboratory of Neutron Physics,JINR,Dubna,Russia |
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Abstract: | Study of the T-odd three-vector correlation in the emission of prompt neutrons from 235U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University
of Munich). The sought correlation was not found within experimental error of 2.3 × 10−5. The upper limit for the asymmetry coefficient has been set to |D
n
| < 6 × 10−5 at 99% confidence level, whereas for ternary fission correlation coefficient D
α
= (170±20) × 10−5. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism.
At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the
rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5° to the fission axis, the correlation
coefficient was found to be (1.57 ± 0.20) × 10−4, while at the angle of 67.5° it is zero within the experimental uncertainty. The existence of ROT effect in the emission
of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission
fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT
effect in the emission of prompt γ-rays. |
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Keywords: | |
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