Parity Nonconservation in Neutron Resonances in 238U

Bret E. Crawford, Gettysburg College
J D. Bowman, Los Alamos National Laboratory
P P J. Delheij, TRIUMF
C M. Frankle, Los Alamos National Laboratory
M IInuma, Kyoto University
J N. Knudsen, Los Alamos National Laboratory
L Y. Lowie, North Carolina State University
A Masaike, Kyoto University
Y Matsuda, Kyoto University
G E. Mitchell, North Carolina State University
S I. Penttila, Los Alamos National Laboratory
H Postma, Delft University of Technology
N R. Roberson, Duke University
S J. Seestrom, Los Alamos National Laboratory
E I. Sharapov, Joint Institute for Nuclear Research
Sharon L. Stephenson, Gettysburg College
Y-F Yen, Los Alamos National Laboratory
V W. Yuan, Los Alamos National Laboratory

Copyright held by American Physical Society. First published as BE Crawford et al, Parity nonconservation in neutron resonances in 238U, Physical Review C, 58:2, 1225–1235, doi: 10.1103/PhysRevC.58.1225.


Parity nonconservation (PNC) was studied for 24 p-wave neutron resonances in 238U from 10 to 300 eV by measuring the helicity dependence of the total neutron cross section with an improved experimental apparatus. Six resonances show statistically significant (greater than 2.9σ) parity violation. An analysis treating the PNC matrix elements as random variables yields a root-mean-square PNC matrix element M=0.67-0.16+0.24 meV. The corresponding weak spreading width Γw=(1.35-0.64+0.97)×10-7 eV.