Regular Article

Fast neutron counting in a mobile, trailer-based search platform

¹ University of Tennessee, Nuclear Engineering Department, 211 Pasqua Engineering Bldg, 37996 Knoxville, USA
² Oak Ridge National Laboratory, One Bethel Valley Rd, P.O. Box 2008, MS-6010, 37931 Oak Ridge, USA

^* e-mail: jhayward@utk.edu

Received: 19 July 2017
Received in final form: 20 September 2017
Accepted: 7 November 2017
Published online: 12 December 2017

Abstract

Trailer-based search platforms for detection of radiological and nuclear threats are often based upon coded aperture gamma-ray imaging, because this method can be rendered insensitive to local variations in gamma background while still localizing the source well. Since gamma source emissions are rather easily shielded, in this work we consider the addition of fast neutron counting to a mobile platform for detection of sources containing Pu. A proof-of-concept system capable of combined gamma and neutron coded-aperture imaging was built inside of a trailer and used to detect a ²⁵²Cf source while driving along a roadway. Neutron detector types employed included EJ-309 in a detector plane and EJ-299-33 in a front mask plane. While the ²⁵²Cf gamma emissions were not readily detectable while driving by at 16.9 m standoff, the neutron emissions can be detected while moving. Mobile detection performance for this system and a scaled-up system design are presented, along with implications for threat sensing.