Parity violation in <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow></mrow><mrow><mn>232</mn></mrow></msup></mrow><mi mathvariant="normal">Th</mi></math></span> neutron resonances above 250 eV

E. I. Sharapov; J. D. Bowman; B. E. Crawford; P. P. J. Delheij; C. M. Frankle; M. Iinuma; J. N. Knudson; L. Y. Lowie; J. E. Lynch; A. Masaike; Y. Matsuda; G. E. Mitchell; S. I. Penttilä; H. Postma; N. R. Roberson; S. J. Seestrom; S. L. Stephenson; Y.-F. Yen; V. W. Yuan

doi:10.1103/PhysRevC.61.025501

Parity violation in $^{232} Th$ neutron resonances above 250 eV

E. I. Sharapov, J. D. Bowman, B. E. Crawford, P. P. J. Delheij, C. M. Frankle, M. Iinuma, J. N. Knudson, L. Y. Lowie, J. E. Lynch, A. Masaike, Y. Matsuda, G. E. Mitchell, S. I. Penttilä, H. Postma, N. R. Roberson, S. J. Seestrom, S. L. Stephenson, Y.-F. Yen, and V. W. Yuan

Phys. Rev. C 61, 025501 – Published 18 January 2000

Abstract

The analysis of parity nonconservation (PNC) measurements performed on $^{232} Th$ by the TRIPLE Collaboration has been extended to include the neutron energy range of 250 to 1900 eV. Below 250 eV all ten statistically significant parity violations have the same sign. However, at higher energies PNC effects of both signs were observed in the transmission of longitudinally polarized neutrons through a thick thorium target. Although the limited experimental energy resolution precluded analysis in terms of the longitudinal asymmetry, parity violations were observed and the cross section differences for positive and negative neutron helicities were obtained. For comparison, a similar analysis was performed on the data below 250 eV, for which longitudinal asymmetries were obtained previously. For energies below 250 eV, the p-wave neutron strength functions for the $J = 1 / 2$ and $J = 3 / 2$ states were extracted: $S_{1 / 2}^{1} = (1.68 \pm 0.61) \times 10^{- 4}$ and $S_{3 / 2}^{1} = (0.75 \pm 0.18) \times 10^{- 4} .$ The data provide constraints on the properties of local doorway states proposed to explain the PNC sign effect in thorium.

Received 7 September 1999

DOI:https://doi.org/10.1103/PhysRevC.61.025501

Authors & Affiliations

E. I. Sharapov¹, J. D. Bowman², B. E. Crawford^3,*, P. P. J. Delheij⁴, C. M. Frankle², M. Iinuma^5,†, J. N. Knudson², L. Y. Lowie^6,‡, J. E. Lynch⁷, A. Masaike^5,§, Y. Matsuda^5,∥, G. E. Mitchell⁶, S. I. Penttilä², H. Postma^8,¶, N. R. Roberson³, S. J. Seestrom², S. L. Stephenson^6,*, Y.-F. Yen^2,**, and V. W. Yuan²

¹Joint Institute for Nuclear Research, 141980 Dubna, Russia
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
⁵Physics Department, Kyoto University, Kyoto 606-01, Japan
⁶North Carolina State University, Raleigh, North Carolina 27695-8202Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308
⁷Gettysburg College, Gettysburg, Pennsylvania 17325
⁸Delft University of Technology, Delft, 2600 GA, The Netherlands

^*Present address: Gettysburg College, Gettysburg, PA 17325.
^†Present address: Hiroshima University, Hiroshima-Ken 739-8526, Japan.
^‡Present address: McKinsey and Company, Atlanta, GA 30303.
^§Present address: Fukui University of Technology, 3-6-1 Gakuen, Fukui-shi, 910-8505, Japan.
^∥Present address: Institute of Physical and Chemical Research (RIKEN), Saitama, 351-0198, Japan.
^¶Present address: IRI/ISO/TUD, 2629 JB Delft, The Netherlands.
^**Present address: Wake Forest University School of Medicine, Winston-Salem, NC 27157.

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Vol. 61, Iss. 2 — February 2000

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