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H. C. Evans; G. T. Ewan; S. -P. Kwan; J. R. Leslie; J. D. MacArthur; H. -B. Mak; W. McLatchie; S. A. Page; P. Skensved; S. -S. Wang; A. B. McDonald; C. A. Barnes; T. K. Alexander; E. T. H. Clifford

doi:10.1103/PhysRevLett.55.791

Parity Mixing of $0^{+}$ and $0^{-}$ Levels in ${}^{18}F$

H. C. Evans, G. T. Ewan, S. -P. Kwan, J. R. Leslie, J. D. MacArthur, H. -B. Mak, W. McLatchie, S. A. Page, P. Skensved, S. -S. Wang, A. B. McDonald, C. A. Barnes, T. K. Alexander, and E. T. H. Clifford

Phys. Rev. Lett. 55, 791 – Published 19 August 1985

Abstract

The circular polarization of the $γ$ rays emitted in the transition from the 1.081-MeV state to the ground state in ${}^{18}F$ has been measured to be (1.6±5.6)× $10^{- 4}$ , corresponding to a parity-nonconserving (PNC) matrix element $| 〈 0^{+}, I = 1 | V^{PNC} | 0^{-}, I = 0 〉 | = 0.03 \pm 0.10$ eV. The weak pion-nucleon coupling constant deduced from the weighted average of all recent ${}^{18}F$ measurements is ( ${0.28}_{- 0.28}^{+ 0.89}$ )× $10^{- 7}$ . This result, together with PNC matrix elements in other experiments, suggests that the isovector weak $NN$ interaction may be strongly suppressed compared with the isoscalar weak $NN$ interaction.

Received 15 July 1985

DOI:https://doi.org/10.1103/PhysRevLett.55.791

Authors & Affiliations

H. C. Evans, G. T. Ewan, S. -P. Kwan, J. R. Leslie, J. D. MacArthur, H. -B. Mak, W. McLatchie, S. A. Page, P. Skensved, and S. -S. Wang^*

Queen's University, Kingston, Ontario K7L 3N6, Canada

A. B. McDonald

Princeton University, Princeton, New Jersey 08544

C. A. Barnes

California Institute of Technology, Pasadena, California 91125

T. K. Alexander and E. T. H. Clifford^†

Chalk River Nuclear Laboratories, Atomic Energy of Canada Limited Research Company, Chalk River, Ontario K0J 1J0, Canada

^*Present address: Department of Modern Physics, China University of Science and Technology, Hefei, Anhwei, People's Republic of China.
^†Present address: TRIUMF, University of British Columbia, 4004 Westbrook Mall, Vancouver, B. C., Canada V6T 2A6.