Effects of T -odd asymmetry of the emission of light charged particles and photons during fission of heavy nuclei by pol
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HYSICS OF NUCLEUS AND FUNDAMENTAL INTERACTIONS
Effects of TOdd Asymmetry of the Emission of Light Charged Particles and Photons during Fission of Heavy Nuclei by Polarized Neutrons A. M. Gagarskiia, I. S. Gusevaa, F. Goennenweinb, Yu. N. Kopachc, M. Muttererd, T. E. Kuz’minae, G. A. Petrova, G. Tyurine, and V. Nesvizhevskyf a
St. Petersburg Nuclear Physics Institute, Russian Academy of Sciences, Gatchina, Leningrad oblast, 188350 Russia email [email protected] b Technische Universitat, Darmstadt, Germany c Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia d Eberhard Karls Universitat Tubingen, Tubingen, Germany e Khlopin Radium Institute, St. Petersburg, 194021 Russia f Institut Laue–Langevin, BP 156, Cedex 9, 38042 Grenoble, France Received January 25, 2011
Abstract—The new physical effects of Todd asymmetry of the emission of light charged particles (LCPs) during the ternary fission of some heavy nuclei by cold polarized neutrons have been experimentally studied. The coefficients of triple scalar and vector correlation of the pulses of light particles and fission fragments (TRI effect) and the fivefold correlation of the same vectors (ROT effect) have been measured. These effects are believed to be caused by the rotation of polarized fissioning system around its polarization direction. The treatment of the experimental data for LCPs in the framework of this hypothesis leads to a good agreement between the calculation results and experimental data. The calculated value of the angle of rotation of the fis sion axis in the ternary fission of the polarized fissioning 236U* compound nucleus was used to process the results of measuring the ROT effect for γ photons from binaryfission fragments of the same nucleus. A satis factory description of these experimental data is obtained which serves a convincing confirmation of the rota tion hypothesis. DOI: 10.1134/S1063774511070133
The first search for the effect of Todd asymmetry in the emission of light charged particles (LCPs) in 233U ternary fission in the form [1] W ( Ω ) = 1 + 〈 D TRI〉 σ ⋅ [ p f × p lp ]
polarization direction at its periodic reverse (0 and 1) and the fragment separation axis, to their sum:
DTRI =
(1)
were performed on the highflux nuclear reactor in Grenoble in 1998 as a part of international collabora tion (Institut Laue–Langevin (ILL), Institute for Theoretical and Experimental Physics (ITEP), St. Petersburg Nuclear Physics Institute (PNPI), Khlopin Radium Institute, and Universities of Tübin gen and Darmstadt (Germany) and Juvascyla (Fin land)). In expression (1), σn is the pseudovector of neutron polarization, pf is the fragment momentum, and plp is the LCP momentum. It was believed [2] that this Todd effect can be used as a test of the principle of timereversal invari ance in nature. The corresponding coefficients of T odd asymmetry (DTRI), which were measured in our experiments, were the ratios of the difference in the count rates of light particles escaping to different sides (up and down) with re
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