ATMOSPHERIC PROTON MICROPROBE FOR TRACE ELEMENT ANALYSIS

WE WILL DEVELOP AN ATMOSPHERIC SCANNING PROTON MICROPROBE (ASPM) FOR ELEMENTAL ANALYSIS OF ORGANIC SPECIMENS. THE INSTRUMENT WILL BE CAPABLE OF MAPPING ELEMENTAL DISTRIBUTIONS IN CONCENTRATIONS AS LOW AS 1 PPM. THE ABILITY TO BRING HIGH ENERGY PROTONS INTO AIR WILL ALLOW THE ANALYSIS OF HYDRATED ORGANIC SPECIMENS WITH LITTLE OR NO SPECIAL PREPARATION, AVOIDING DISTORTION OF THE ELEMENTAL DISTRIBUTIONS. THE ASPM USES PROTON INDUCED X-RAY EMISSION (PIXE), A GENERAL ANALYSIS TECHNIQUE FOR BULK SPECIMENS. THE USE OF A COLLIMATED PROTON BEAM, SCANNING STAGE AD VACUUM WINDOW WILL PROVIDE THE CAPABILITY TO ANALYZE THE SPECIMEN IN AIR WITH MODERATE SPATIAL RESOLUTION (>10 MICRONS)> PHASE I RESEARCH WILL BE USED TO INSTRUMENT AN EXISTING TEST BEAMLINE. A PERSONAL COMPUTER-BASED ACQUISITION AND CONTROL SYSTEM WILL BE DEVELOPED FOR AREA MAPPING AND DISPLAY. THE RESULTING SYSTEM WILL BE USED TO EVALUATE THE USE OF LOW ENERGY (.5-2 MEV) PROTON BEAMS FOR THE ANALYSIS OF ORGANIC SPECIMENS, WITH THE GOAL OF IDENTIFYING A MINIMUM ENERGY ACCELERATOR SUITABLE FOR DEVELOPMENT INTO A SELF-CONTAINED ANALYTICAL TOOL. PHASE II WILL BE USED TO PRODUCE THE PROTOTYPE OF A DEDICATED SYSTEM INCLUDING ACCELERATOR, BEAMLINE, AND CONTROL SYSTEM.