Parity nonconservation in neutron resonances in 232Th

S. L. Stephenson, J. D. Bowman, B. E. Crawford, P. P. J. Delheij, C. M. Frankle, M. Iinuma, J. N. Knudson, L. Y. Lowie, A. Masaike, Y. Matsuda, G. E. Mitchell, S. I. Penttilä, H. Postma, N. R. Roberson, S. J. Seestrom, E. I. Sharapov, Y.-F. Yen, and V. W. Yuan
Phys. Rev. C 58, 1236 – Published 1 August 1998
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Abstract

Parity nonconservation (PNC) was measured for 24 p-wave resonances from 8 to 300 eV in 232Th by measuring the helicity dependence of the total neutron cross section for epithermal neutrons with an improved experimental system. Ten resonances show statistically significant parity violation. For these ten resonances the analyzing powers are all positive, thus confirming the previously observed sign correlation. The data are fit to the sum of two terms, a constant asymmetry and a fluctuating asymmetry. With this ansatz the root-mean-square PNC matrix element M=1.12 meV, which corresponds to a weak spreading width Γw=4.7×107 eV. For the neighboring nuclide 238U there is no constant offset, suggesting that the sign correlation is specific to 232Th.

  • Received 6 April 1998

DOI:https://doi.org/10.1103/PhysRevC.58.1236

©1998 American Physical Society

Authors & Affiliations

S. L. Stephenson1,*, J. D. Bowman2, B. E. Crawford3,†, P. P. J. Delheij4, C. M. Frankle2, M. Iinuma5,‡, J. N. Knudson2, L. Y. Lowie1,§, A. Masaike5, Y. Matsuda5, G. E. Mitchell1, S. I. Penttilä2, H. Postma6, N. R. Roberson3, S. J. Seestrom2, E. I. Sharapov7, Y.-F. Yen2,∥, and V. W. Yuan2

  • 1North Carolina State University, Raleigh, North Carolina 27695-8202Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308
  • 2Los Alamos National Laboratory, Los Alamos, New Mexico 87545
  • 3Duke University, Durham, North Carolina 27708Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308
  • 4TRIUMF, Vancouver, British Columbia, Canada V6T 2A3
  • 5Department of Physics, Kyoto University, Kyoto 606-8502, Japan
  • 6University of Technology, Delft, 2600 GA, The Netherlands
  • 7Joint Institute for Nuclear Research, 141980 Dubna, Russia

  • *Present address: Gettysburg College, Gettysburg, PA 17325.
  • Present address: North Carolina State University, Raleigh, NC 27695-8202 and Gettysburg College, Gettysburg, PA 17325.
  • Present address: Hiroshima University, Hiroshima-Ken 739-8526, Japan.
  • §Present address: McKinsey and Company, Atlanta, GA 30303.
  • Present address: Wake Forest University School of Medicine, Winston-Salem, NC 27157.

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Vol. 58, Iss. 2 — August 1998

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