L. Holewa, W.S. Charlton,
"Angular Anisotropy of Correlated Neutrons and Application to Detection and Verification,"
Proceedings of the INMM 52nd Annual Meeting
, Palm Desert, CA, July 17-21, 2011.
It has been shown that neutrons emitted from the same Cf-252
fission event are preferentially emitted within small angles of
each other and at angles around 180 degrees. In order to reach this
conclusion, a Cf-252 source was placed in the center of an array of
liquid scintillators and data was taken in list-mode. Previous work
has focused on neutron angular distribution relative to the fission
fragments. By considering the angular distribution between neutrons
from the same fission event, information about preferential
emission of neutrons from the same or opposite fission fragments is
captured. After finding through simulation the extent to which
neutron double scattering should occur in the system for a Cf-252
source, the effects of neutron double scattering for various angles
were accounted for. After analysis of the data, it appears that
neutrons are more likely to be emitted from the same fragment.
Because different fissioning radioisotopes have different
distributions of fission fragments, there should be differences in
the distributions of angles between neutrons from the same fission
event for different isotopes. It is this uniqueness that makes
knowledge of the distribution of angles between neutrons from the
same fission event useful for detection and verification of
radioistopes. The specifications of a practical system that
identifies radioisotopes in cargo containers were determined.
Associated Project(s):SHIELD (Smuggled HEU Interdiction through Enhanced anaLysis and Detection): A Framework for Developing Novel Detection Systems Focused on Interdicting Shielded HEU