Detection of hidden explosives by using tagged neutron beams with sub-nanosecond time resolution

Non-destructive inspection of luggage has been simulated in laboratory conditions by using a 14 MeV tagged neutron beam and BaF2 scintillation detectors (Tagged Neutron Inspection System, TNIS). The tagged, neutron beam is produced by detecting the associated alpha particle emitted in the D+T reaction by means of a YARCe scintillator. The TNIS intrinsic time resolution has been measured to be delta t = 0.9 ns [FWHM], which allows inspection of a minimum voxel of 5 cm depth along the neutron flight path. This characteristic is demonstrated by identifying graphite and water samples hidden inside a hard plastic suitcase filled with background material. Finally, explosive devices such as small anti-personnel or anti-tank landmines have been inspected when, placed inside the suitcase. In the case of relatively large explosive objects such as an anti-tank landmine, the system is capable of testing directly the TNT charge inside the device, separating this material from the external plastic case-Further developments of the TNIS concept are discussed.