A portable discrete frequency NQR explosives detection system

This paper describes realization of a prototype discrete-frequency self-contained NQR system into a small portable battery powered form-factor capable of detecting and classifying explosive ingredients such as sodium nitrite, ammonium nitrate, RDX, HMX, PETN, potassium nitrate, tetryl, urea nitrate, and glycine. Size is similar to the smallest commercially available NMR spectrometer, but includes all system components. This version uses fixed frequencies and simple pulse sequences to prove feasibility. Results include signature amplitude variation as a function of both sample mass and standoff, and detection unaffected by presence of both metallic and non-metallic clutter.