Use of CLYC spectrometer in counter-terrorism applications

Abstract

ABSTRACT A new scintillator crystal, now known as CLYC (Cs 2 LiYCl 6 :Ce), has been under development for over 15 years (1) . It was primarily of interest for radiation de tection applications because of its good energy resolu tion for gamma rays (< 4% for 662 keV gamma rays) and its capability for detection of th ermal neutrons. The pulse shapes of the signals from the two radiations are different, which allow them to be separated electronically, permitting simultaneous detection of gamma rays and neutrons. The crystal is now commercially available. Early investigations of the neutron response by the current authors (2) revealed that CLYC also responds to fast neutrons. In fact, the good energy resolution of the response under monoenergetic neutron irradiations showed that CLYC was an excellent high-energy neutron spectrometer. This discovery has great impact on the field of neutron spectroscopy, which has numerous, although often specialized, applications. This presentation focuses on app lications in counter-terrorism scenarios where neutrons may be involved. The relative importance of the fast neutron response of CLYC, compared to the thermal and gamma-ray response, will be discusse d for these scenarios. (1) C.M. Combes, P. Dorenbos, C.W.E. van Eijk, K.W. Kramer, H.U. Gudel, J. Lumin. 82 (1999) 299-305 (2) M.B. Smith, T. Achtzehn, H.R. Andrew s, E.T.H. Clifford, H. Ing, V.D. Kovaltchouk, IEEE Trans. Nucl. Sci 60(2) (2013) 855-859 *This work has been supported by the US Department of Defense, Defense Threat Reduction Agency, under competitively awarded contract HDTRA1-12-C-0005. This support does not constitute an express or implied endorsement on the part of the Government. DISTRIBUTION A. Approved for public release: distribution unlimited. Keywords: Radiation Detection, CLYC, Counter-terrorism, GEANT4