A common method of inspecting commercial cargoes for the presence of fissile materials involves the use of 1-10MeV bremsstrahlung photon beams. While simple and reliable, this technique has many downsides, such as the large doses involved and its relative inefficiency at triggering NRF and photofission. Much progress in the field of active interrogation can be achieved by developing monochromatic, and possibly tunable gamma sources:
(1) monochromatic or quasi-monochromatic sources will allow for lower dose radiography and photofission based active interogation.(2) tunable sources will increase the signal/dose for NRF applications, and will potentially reduce the required measurements times.
Currently, a collaboration lead by MIT is exploring the possibility of using proton and deuteron beams in 11B(d,nγ)12C and 12C(p,p’γ)12C reactions, which produce highly monochromatic photons.This program makes use of a 3MeV deuteron source at MIT-Bates linear accelerator to experiment with (d,nγ) reactions. This approach can be used not only to achieve low dose radiography, but also low dose dual energy radiography and lower dose photofission for fissionable material detection.