Recent improvements in on-site detection and identification of radioactive/nuclear material

Sensitive mobile detection systems are important to detect and prevent illicit trafficking of radioactive and nuclear material. Recently, new mobile systems for low and high resolution gamma detection have become available which have new features that enhance the detection possibilities and ease the use of hand-held systems. One improvement is the utilization of improved scintillation material like Lanthanum Bromide (LaBr3) which offers a factor of 2-3 in energy resolution compared to the widely used Sodium Iodide (NaI). An other enhancement is the use of Stirling Coolers for High Purity Germanium (HPGe) detectors which now have become lighter and more reliable and allow building high resolution detectors without the need for liquid nitrogen. These systems are really portable now and can be used as mobile search devices. Such devices have been investigated also. On the other hand also new mobile neutron detection systems came on the market which comprise advanced detection and, to some extend, also identification methods. Although mobile neutron detection systems are less common in typical mission scenarios they play an important role in some special cases, in particular if nuclear material is involved. Because the use of an improvised nuclear device (IND) by terrorists may have vast consequences the identification of nuclear material in such a special device is extremely important. Nuclear material can be identified by the detection of coincidence neutrons or, although with less constraint, also by evaluating the neutron spectra. Devices using both methods, which are hand-held or at least portable, have been investigated