THE FEASIBILITY OF A THIN FOIL/MICROCHANNEL-PLATE DETECTOR SYSTEM FOR DIAGNOSTIC IMAGING OF ENERGETIC CHARGED PARTICLE BEAMS

DURING THE PAST FIVE YEARS, EXTENSIVE DEVELOPMENTAL EFFORT HAS LED TO THE PRODUCTION OF COMPUTER-COMPATIBLE POSITION-SENSITIVE ION DETECTION SYSTEMS FOR STIGMATIC IMAGING, SECONDARY-ION MASS SPECTROMETRY. A TREMENDOUS BODYOF KNOWLEDGE AND SEVERAL PRODUCTS HAVE RESULTED FROM THIS WORK, WITH APPLICATIONS TO THE LOW ENERGY ION BEAM REGIME (KEV). THE OBJECTIVE OF THIS PHASE I RESEARCH PROJECT IS TOASSESS THE FEASIBILITY OF TRANSFERRING SOME OR ALL OF THIS TECHNOLOGY TO THE NONDESTRUCTIVE TWO-DIMENSIONAL DETECTION OF HIGH ENERGY PARTICLE BEAMS. THE BASIC APPROACH TO BE EVALUATED WILL CONSIST OF COLLIDING THE HIGH ENERGY BEAM WITH A LOW MASS DENSITY/LOW Z THIN FOIL TRANSDUCER FROM WHICH SECONDARY ELECTRONS WILL BE PRODUCED. THESE SECONDARYELECTRONS WILL BE FOCUSED ONTO A MICROCHANNEL PLATE (MCP) INTENSIFIER USING PROXIMITY FOCUSING OR STIGMATIC ELECTRON EXTRACTION OPTICS. THE AMPLIFIED ELECTRON SIGNAL PRODUCED BY THIS MCP INTENSIFIER WILL BE ACCELERATED ONTO A FLUORESCENT SCREEN DETECTOR, VIEWED WITH A VIDEO CAMERA, A RESISTIVE ANODE ENCODER WITH A POSITION COMPUTER, OR A HYBRID COMBINATION OF THE TWO. THE FEASIBILITY OF THESE VARIOUS DETECTOR STRATEGIES IN DETERMINING THE SPATIAL DISTRIBUTION OF HIGH ENERGY BEAMS WILL BE EVALUATED USING 1-5 MEV HE OR O BEAMS PRODUCED IN A 1.2 MEV TANDEM ION ACCELERATOR CONVENTIONALLY EMPLOYED FOR RUTHERFORD BACKSCATTERING SPECTROMETRY.