T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

Journal Article · Sun May 15 04:00:00 EDT 2011 · Physics of Atomic Nuclei

DOI:https://doi.org/10.1134/S1063778811050061· OSTI ID:22029913

Danilyan, G V ^[1]; Klenke, J ^[2]; Krakhotin, V A; Kopach, Yu N; Novitsky, V V; Pavlov, V S; Shatalov, P B ^[1]

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1. Institute for Theoretical and Experimental Physics (Russian Federation)
2. Forschungs-Neutronenquelle Heinz Meier-Leibnitz (FRM II) (Germany)

Study of the T-odd three-vector correlation in the emission of prompt neutrons from {sup 235}U 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 Multiplication-Sign 10{sup -5}. The upper limit for the asymmetry coefficient has been set to vertical bar D{sub n} vertical bar < 6 Multiplication-Sign 10{sup -5} at 99% confidence level, whereas for ternary fission correlation coefficient D{sub {alpha}} = (170{+-}20) Multiplication-Sign 10{sup -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 Degree-Sign to the fission axis, the correlation coefficient was found to be (1.57 {+-} 0.20) Multiplication-Sign 10{sup -4}, while at the angle of 67.5 Degree-Sign 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 {gamma}-rays.

• OSTI ID: 22029913
• Journal Information: Physics of Atomic Nuclei, Journal Name: Physics of Atomic Nuclei Journal Issue: 5 Vol. 74; ISSN 1063-7788; ISSN PANUEO
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR CORRELATION
ANISOTROPY
ASYMMETRY COEFFICIENTS
COLD NEUTRONS
CORIOLIS FORCE
FISSION FRAGMENTS
FRM-II REACTOR
GAMMA RADIATION
NEUTRON BEAMS
NEUTRON EMISSION
NEUTRON REACTIONS
NUCLEAR DEFORMATION
POLARIZED BEAMS
PROMPT NEUTRONS
ROTATION
TERNARY FISSION
URANIUM 235