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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:29 |
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Conference: Bucharest University Faculty of Physics 2018 Meeting
Section: Nuclear and Elementary Particles Physics
Title:
Parity violation effects in capture of slow neutrons by Lead
Authors:
Cristina OPREA, Alexandru Ioan OPREA
Affiliation:
C. Oprea, A.I. Oprea, Yu. M. Gledenov, P.V. Sedyshev
E-mail
ionica@nf.jinr.ru
Keywords:
Parity violation effects, weak matrix element, slow neutrons, capture process
Abstract:
Parity violation effects (PV) in nuclear reaction were discovered in the ’60
years of the last century in the capture of thermal transversal polarized neutrons by
113Cd nucleus. In this reaction experimentally was measured a non zero asymmetry of
emitted gamma quanta and the results was interpreted by the existence of weak non
leptonic interaction between nucleons in the compound nucleus. This first experimental
result gave a serious impulse of theoretical and experimental developments of parity
violation question in nuclear reactions.
The weak interaction acts in the background of strong interaction (with order of
magnitude higher) and therefore it is very difficult to observe and evidence it. One
possibility is the evaluation of asymmetry effects induced by PV phenomena.
For neutrons scattering there are a few asymmetry effects (like polarization of
incident neutron beam, spin rotation and emitted neutrons asymmetry of incident
transversal polarized neutrons) explained by the presence of weak interaction.
In natural Lead were observed an unexpected high value of neutron spin
rotation due to the PV phenomena. The natural Lead contains four isotopes and the
main contribution to the PV effects is given by 204Pb. Further to explain the high value of
neutron spin rotation it was supposed the existence of a new negative P resonance with energy EP = - 16 eV.
In this work were estimated the PV effects in scattering in order to extract the weak matrix element and to verify the existence of the new negative resonance of 204Pb nucleus.
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