A HIGH COUNT RATE TWO-DIMENSIONAL NEUTRON DETECTOR

MOST MAJOR NEUTRON FACILITIES OPERATING IN THE U.S. WERE DEVELOPED TWO OR THREE DECADES AGO. TO MEET THE NEW CHALLENGES FOR MATERIALS AND BIOLOGICAL RESEARCH IN THE FUTURE, A NEW GENERATION OF NEUTRON FACILITIES WITH MUCH HIGHER FLUX AND WITH COMPATIBLE INSTRUMENTATION IS BEING CONSIDERED. THE CURRENT TECHNOLOGY OF NEUTRON DETECTION (GAS-FILLED, PROPORTIONAL, POSITION-SENSITIVE CHAMBERS) COULD NOT MEET THE NEEDS IN AN ADVANCED NEURTRON SOURCE ENVIRONMENT BECAUSE OF THE INHERENTLY LIMITED MAXIMUM COUNT RATE, LIMITED SPATIAL RESOLUTION, AND LIMITED DETECTION EFFICIENCY, ESPECIALLY FOR NEUTRONS WITH SHORTER WAVELENGTH. TO MEET THE NEEDS FOR NEUTRON SCATTERING AND NEUTRON DIFFRACTION EXPERIMENTS AT HIGHER NEUTRON FLUXES, THIS PHASE I PROJECT WILL STUDY THE DEVELOPMENT OF A LARGE FORMAT, INTEGRATED, AMORPHOUS SILICON, PHOTODIODE ARRAY COUPLED WITH AN EFFICIENT SCINTILLATOR. THE NOVEL TWO-DIMENSIONAL NEUTRON DETECTOR IS EXPECTED TO BE ABLE TO IMPROVE THE MAXIMUM COUNT RATE FROM THE CURRENT 10(5)-10(6)/SECOND GIVEN BY A GAS-FILLED CHAMBER TO 10(8)-10(9)/SECOND, RESULTING IN SIGNIFICANTLY IMPROVED PRODUCTIVITY AND DATA THROUGHPUT. SPATIAL RESOLUTION IS EXPECTED TO BE ENHANCED FROM THE CURRENT 5 MM LEVEL TO A SUBMILLIMETER LEVEL. PARALLAX ERROR PRODUCED BY GAS-FILLED DETECTORS WILL BE ELIMINATED, AND AT THE SAME TIME DETECTION EFFICIENCY FOR SHORTER WAVELENGTH (DOWN TO 0.5A) NEUTRONS WOULD ALSO BE SUBSTANTIALLY IMPROVED. PHASE I SHOULD DEMONSTRATE FEASIBILITY OF THE PLANNED APPROACH, AND PHASE II WOULD PROVIDE A PROTOTYPE TWO-DIMENSIONAL NEUTRON DETECTOR.