ULTRAVIOLET-SENSITIVE LARGE-AREA AVALANCHE PHOTODIODES FOR IMPROVED CALORIMETRY

THIS PROJECT WILL EXTEND THE RESPONSIVITY OF CURRENTLY AVAILABLE LARGE-AREA AVALANCHE PHOTODIODES (APDS) INTO THE BLUE AND NEAR-UV REGION. APDS CAN OFFER SIGNIFICANT COST SAVINGS AND SUPERIOR PERFORMANCE (HIGH QUANTUM EFFICIENCY, COMPACTNESS, RUGGEDNESS, FREEDOM FROM AFTERPULSING, MAGNETIC FIELD IMMUNITY, AND FAST TIME RESPONSE) OVE2R PHOTMULTIPLIE2RS. DURING PHASE I, TWO PARALLEL APPROACHES WILL BE EXPLORED TO ENHANCE APD'S BLUE AND NEAR-UV RESPONSIVITY USING BORON IMPLANTATION AND WAVELENGTH-SHIFTING PHOSPHOR COATING. THE GOAL IS TO ACHIEVE A 40% QUANTUM EFFICIENCY IN THE WAVELENGTH REGION 200-450 NN. A CUCCESSFUL COMPLETION OF PHASE I WILL DEMONSTRATE THE FEASIBILITY OF THE TECHNICAL APPROACH. PHASE II WOULD OPTIMIZE THESE PROCESSES FLUXES OF LESS THAN 1000 W/CM(2). POROUS METAL COOLING WILL INCREASE THE POWER CAPABILITY AND DESIGN MARGIN FOR THE KLYSTRON COLLECTOR. TASKS TO BE COMPLETED IN PHASE I INCLUDE DEFINING DETAILED REQUIREMENTS FOR THE COLLECTOR, COMPLETING A CONCEPTUAL DESIGN OF A POROUS METAL COOLED HEAT EXCHANGER FOR THE TARGET APPLICATION, AND DEMONSTRATION OF A SUBSCALE TEST ARTICLE TO REMOVE AN ABSORBED HEAT FLUX GOAL OF 1000 W/CM(2) USING POROUS METAL COOLING.