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Experiments on Parity Non-Conservation in Nuclear Forces in ¹⁸⁰Hf, ¹⁵⁹Tb, ²⁰³Tl-203 and ¹⁸¹Ta


Lipson, Edward David (1971) Experiments on Parity Non-Conservation in Nuclear Forces in ¹⁸⁰Hf, ¹⁵⁹Tb, ²⁰³Tl-203 and ¹⁸¹Ta. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/NQ36-P768.


Weak interaction theories of the "current-current” form predict a weak parity-non-conserving force between nucleons. One manifestation of such a force is the net circular polarization of γ rays from unoriented nuclei. We have measured the circular polarization for four favorable nuclear γ transitions obtaining

180Hf 501 keV γ: pγ = (-23 ± 6) x 10-4
159Tb 363 keV γ: pγ = (-1 ± 5) x 10 -4
203Tl 279 keV γ: Pγ = (-0.04 ± 0.10) x 10-4
181Ta 482 keV γ: pγ = (-0.031 ± 0.025) x 10 -4

The measurements were performed with a forward-scattering rapidly reversing Compton polarimeter and a phase-sensitive detection system. The analyzing efficiency of the Compton polarimeter, including effects of multiple scattering, was determined by Monte Carlo calculations. It was necessary in most experiments to apply corrections for polarized bremsstrahlung associated with β decays. Calculations of bremsstrahlung effects were verified by experiments on 198 Au and 177Lu. The residual asymmetry of the polarimeter itself was determined by contro1 experiments on103Ru.

The values of Pγ obtained are compared with related experiments and discussed in the framework of nuclear and weak-interaction theories.

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:13 May 1971
Funding AgencyGrant Number
U.S. Atomic Energy CommissionUNSPECIFIED
Record Number:CaltechTHESIS:06082018-121644195
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11051
Deposited On:25 Jun 2018 21:04
Last Modified:21 Dec 2019 04:08

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