A PARTICLE IDENTIFICATION DETECTOR FOR LOW MEV IONS

THIS RESEARCH ADDRESSES THE NEED FOR IMPROVED ANALYTICAL CAPABILITIES IN THE ANALYSIS OF THE NEAR SURFACE COMPOSITION AND DEPTH DISTRIBUTION OF LOW Z ELEMENTS (I.E., THOSE HAVING LOW CHARGE NUMBERS, SUCH AS C, N, AND O) IN MATERIALS SYSTEMS SUCH AS POLYMERS AND PLASTICS. THE RESEARCH OBJECTIVE IS TO DEVELOP A SIMPLE, LOW COST IDENTIFICATION SYSTEM FOR DETECTING LOW Z PARTICLES GENERATED BY ELASTIC RECOIL WITH AN ENERGETIC PARTICLE BEAM. THE NOVEL CONCEPT TO BE ADVANCED BY THIS NEW DETECTION SYSTEM IS THAT THE RISE TIME AND INTEGRATED CHARGE (PULSE HEIGHT) FROM A COMBINED TARGET CHAMBER/GAS PROPORTIONAL COUNTER CAN PROVIDE BOTH IN-DEPTH AND COMPOSITIONAL ANALYSIS. THE AVAILABILITY OF THIS NEW TECHNIQUE WILL POTENTIALLY LEAD TO A BETTER UNDERSTANDING OF VARIOUS MATERIALS SYSTEMS (E.G., ORGANIC OR POLYMERIC COATINGS). IT MAY ALSO LEAD TO THE DEVELOPMENT OF NOVEL MATERIALS WITH UNIQUE AND/OR INNOVATIVE PROPERTIES. IN PHASE I, A GRIDDED PROPORTIONAL COUNTER AND CHAMBER ARE BEING CONSTRUCTED. SEVERAL DIFFERENT POLYMER SAMPLES ARE BEING IRRADIATED WITH MEV BEAMS OF NEON AND ARGON, INCLUDING THIN FILMS OF NYLON, POLYETHYLENETEREPHTHALATE, POLYPROPYLENE FIBERS, AND POLYIMIDE THIN FILMS. THE ENERGY AND INTENSITY OF ELASTIC RECOIL DETECTION (ERD) PARTICLES RESULTING FROM THE IRRADIATION OF THE ABOVE SAMPLES WILL BE MEASURED. THE TIME RISE DIFFERENCE FOR H,C,N AND O ERD PARTICLES IS BEING MEASURED IN THE NEW PROPORTIONAL COUNTER. A TWO-PARAMETER SPECTRUM (ENERGY VS. RISE TIME) WILL THEN BE ACQUIRED TO DEMONSTRATE PARTICLE SPECIATION.