A TUNABLE, MONOCHROMATIC X-RAY GENERATOR FOR EXPLOSIVES DETECTION

PARAMETRIC X-RADIATION (PXR) IS PROPOSED AS AN INTENSE, TUNABLE, MONOCHROMATIC HARD-X-RAY SOURCE FOR THE DETECTION OF EXPLOSIVES. THIS RADIATION IS HIGHLY COLLIMATED, HAS A BANDWIDTH OF 0.1, AND AN INTENSITY EQUAL TO THAT OF SYNCHROTRON RADIATION ON A PER ELECTRON BASIS. PXR GENERATION IS ACHIEVED BY PLACING CRYSTALS INTO THE PATH OF ELECTRON BEAMS WITH ENERGY OF 6 MEV OR GREATER. THE VIRTUAL PHOTONS ASSOCIATED WITH THE FIELDS OF THE ELECTRONS ARE BRAGG REFLECTED BY THE CRYSTAL LATTICE AND REAL X-RAYS APPEAR AT THE BRAGG ANGLE. THE PRODUCTION IS THUS ANALOGOUS TO X-RAY DIFFRACTION EXCEPT THAT THE X-RAY BEAM INCIDENT AT THE BRAGG ANGLE IS REPLACED BY A RELATIVISTIC ELECTRON BEAM. PREVIOUS RESEARCH BY US AND OTHERS HAVE DEMONSTRATED THAT X-RAYS WITH ENERGIES OF E 50 KEV) CAN BE PRODUCED WITH GOOD EFFICIENCY. DURING THE PHASE I RESEARCH WE WILL DESIGN RADIATORS FOR 50 KEV EMISSION, CALCULATE THEIR THEORETICAL X-RAY FLUX, AND MEASURE EXPERIMENTALLY THEIR HARD-R-RAY SPECTRUM USING PULSE HEIGHT ANALYSIS.