NCJ Number
45666
Date Published
1975
Length
103 pages
Annotation
THE USES AND LIMITATIONS OF VARIOUS RADIOFREQUENCY RESONANCE ABSORPTION SPECTROSCOPY TECHNIQUES IN DETECTING EXPLOSIVE IN AIRLINE LUGGAGE ARE DESCRIBED.
Abstract
THE RADIOFREQUENCY RESONANCE ABSORPTION SPECTROSCOPY (RRAS) TECHNIQUES CONSIDERED IN THIS STUDY INCLUDED NUCLEAR MAGNETIC RESONANCE (NMR), ELECTRON SPIN RESONANCE (ESR), AND NUCLEAR QUADRUPOLE RESPONANCE (NQR) IT WAS FOUND THAT ALL THE EXPLOSIVES, EXCEPT BLACK POWDER, COULD BE DETECTED BY NMR AND THAT THE NMR RESPONSE FROM EXPLOSIVES COULD BE SEPARATED FROM THE RESPONSE PRODUCED BY OTHER MATERIALS LIKELY TO BE FOUND IN LUGGAGE. IT WAS ALSO FOUND THAT BLACK POWDER AND SMOKELESS POWDERS COULD BE DETECTED BY ESR, BUT NONE OF THE OTHER EXPLOSIVES PRODUCED AN ESR RESPONSE. NQR WAS FOUND USEFUL ONLY FOR THE DETECTION OF THE RDX BASE EXPOLSIVE C-4, BUT EVEN THIS MATERIAL COULD BE MORE SENSITIVELY DETECTED BY NMR. A MAGNET AND DETECTION COIL THROUGH WHICH BAGGAGE WITH CROSS SECTIONAL DIMENSIONS UP TO 14 BY 24 INCHES COULD BE PASSED FOR INSPECTION WAS CONSTRUCTED AND TESTED. THE RESULTS WERE SUFFICIENT TO DEMONSTRATE THE BASIC FEASIBILITY OF USING NMR FOR DETECTION OF RESPONSES FROM MATERIALS IN THE LARGE VOLUMES REQUIRED TO INSPECT CHECKED BAGGAGE, BUT LIMITATIONS ON THE AVAILABLE LABORATORY EQUIPMENT PREVENTED POSITIVE DETECTION OF EXPLOSIVES OR EXPLOSIVES SIMULANTS IN THIS SPACE. THE DETECTION SENSITIVITY WAS SUCH, WITH THE AVAILABLE APPARATUS, THAT AN EXPLOSIVE SIMULANT EQUIVALENT TO TWO STICKS OF DYNAMITE COULD BE DETECTED IN A VOLUME ADEQUATE FOR INSPECTING LARGE ATTACHE CASES. INCREASED RF POWER FROM THE LABORATORY APPARATUS IS NEEDED TO DETECT EXPLOSIVES IN THE LARGER VOLUME. TESTS WITH POTENTIALLY INTERFERING MATERIALS IN THE ATTACHE CASE SHOWED NO SERIOUS PROBLEMS. TESTS WITH ESR SHOWED ADEQUATE SENSITIVITY TO DETECT ONE POUND OF BLACK POWDER IN AN INSPECTION REGION OF ADEQUATE EXTENT TO ACOMMODATE CHECKED LUGGAGE. FROM THE RESULTS OF THE TESTS, IT WAS CONCLUDED THAT THE USE OF HYDROGEN NMR APPEARS FEASIBLE FOR USE IN DETECTING ALL EXPLOSIVES OF INTEREST, EXCEPT BLACK POWDER. NMR APPARATUS WITH ADEQUATE CHARACTERISTICS TO DETECT THE REQUIRED QUANTITIES OF THESE EXPLOSIVES IN THE SPECIFIED SIZE OF CHECKED BAGGAGE ALSO APPEARS FEASIBLE. DETECTION OF BLACK POWDER ALSO APPEARS FEASIBLE BY COMBINING ESR WITH THE NMR. (AUTHOR ABSTRACT MODIFIED--RCB)