Gamma-Insensitive Fast Neutron Detector with Spectral Source Identification Potential [open pdf - 554KB]
"Calculations are presented to support the claim that fast neutron detection systems can achieve higher performance in detecting weak neutron sources than conventional thermal neutron detection systems involving moderators. Minimum Detectable Limits (MDL) are used as a comparative metric, more representative than the metric of absolute sensitivity, which does not take into account the influence of natural backgrounds. Monte Carlo simulations are used to show that heavily shielded neutron sources emit a substantial fraction of fast neutrons. Arguments are presented to support the claim that fast neutron detection systems are superior at defeating heavy neutron shielding than thermal systems."
2011 Naval Postgraduate School (U.S.). Center for Homeland Defense and Security. Posted here with permission. Documents are for personal use only and not for commercial profit.
Homeland Security Affairs Journal: http://www.hsaj.org/
Homeland Security Affairs (March 2011), Supplement no.3