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Experimental study of time reversal invariance and atomic final state effects in nuclear transitions

Citation

Gimlett, James L. (1980) Experimental study of time reversal invariance and atomic final state effects in nuclear transitions. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/n7sw-jy41. https://resolver.caltech.edu/CaltechTHESIS:10272016-131924862

Abstract

Experiments have been performed to test time reversal invariance in nuclei using gamma transitions of oriented 191Ir and 131Xe. The phase angle η associated with the imaginary part of the ratio of reduced matrix elements of the gamma transition was measured through observation of the angular distribution of the linear polarization from oriented nuclei. Interaction of the gamma ray with the atomic electron cloud can cause an additional phase shift ξ which is indistinguishable from the time-reversal phase η. Such an atomic final state effect has been observed for the 129 keV transition in 191Ir. Nuclear orientation was achieved with a large magnetic field (the hyperfine field of Ir in iron) and low temperature (20 to 30 mK obtained with a dilution refrigerator). A Compton polarimeter was used to measure linear polarization of the E2-Ml gamma ray. The matrix-element ratio was found to have an imaginary part corresponding to a phase angle (η+ξ) = (-4.8 ± 0.2) x 10-3. This measurement is in agreement with the most recent final state calculations which give ξ = (-4.3 ± 0.4) x 10-3. A limit |η| < 10-3 is deduced for the time-reversal phase. In another experiment a phase angle η = (-1.2 ± 1.1) x 10-3 was measured for the E2-Ml 364 keV transition in 131Xe, for which atomic final state effects are small. Both measurements are consistent with time reversal invariance.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Boehm, Felix H.
Thesis Committee:
  • Unknown, Unknown
Defense Date:5 May 1980
Funders:
Funding AgencyGrant Number
CaltechUNSPECIFIED
Schlumberger FoundationUNSPECIFIED
Energy Research and Development AgencyUNSPECIFIED
Record Number:CaltechTHESIS:10272016-131924862
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:10272016-131924862
DOI:10.7907/n7sw-jy41
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9961
Collection:CaltechTHESIS
Deposited By: Benjamin Perez
Deposited On:27 Oct 2016 22:41
Last Modified:16 Apr 2021 22:57

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