Monte Carlo Simulations of Powerful Neutron Interaction with Matter for the Goals of Disclosure of Hidden Explosives and Fissile Materials and for Treatment of Cancer Diseases versus their Experimental Verifications

A single-shot nanosecond neutron pulsed technique for the detection of fissile materials

“…We should like to analyze an opportunity to apply this technique for interrogation of items containing fissile materials. One very preliminary result on this point with a single oscilloscope trace was presented in our work [11]. In this paper we describe all results obtained during the above-mentioned experimental session.…”

“…lower speed v of scattered neutrons) will result in a later time of arrival of the scattered neutrons to a detector -in our case it is a photomultiplier with plastic scintillator (PMT+S) -compared with the arrival time of "direct" neutrons coming to the detector from the source without scattering [1,8]. Taking into consideration these time lags, amplitudes of pulses and corresponding cross-sections of scattering it is possible to reconstruct an elemental content of the material under interrogation from an oscilloscope trace [1,8,9,11]. However, as one may see from figure 2, this difference between energy of direct neutrons coming from the source to the detector and elastically scattered by the nuclei becomes negligible for heavy nuclei comprising fissile materials (elements like Th, U, etc.…”

“…It is easy to estimate how many neutrons Nwe have registered in the above pulses associated with the fuel assembly. According to MCNP calculations their intensity at the distance 6 m from 11 neutrons per pulse in full solid angle). This statistics is above the border of acceptability presented in the section 2 (minimal number of registered mono-energetic neutrons must be higher than 10).…”