INDIUM IODIDE PHOTOCONDUCTIVE DETECTORS FOR USE IN SCINTILLATION SPECTROSCOPY

CURRENTLY, SCINTILLATION SPECTROMETERS ARE WIDELY USED FOR DETECTION AND SPECTROMETRY OF ENERGETIC PHOTONS (X-RAYS AND GAMMA-RAYS) AT ROOM TEMPERATURE. THESE SPECTROMETERS FIND EXTENSIVE APPLICATION IN NUCLEAR AND HIGH ENERGY PHYSICS EXPERIMENTS, MEDICAL IMAGING SYSTEMS, AND VARIOUS INDUSTRIAL GAUGING APPARATUSES. ALTHOUGH THE IMPROVEMENTS IN SCINTILLATOR CRYSTAL TECHNOLOGY HAVE EXTENDED THE UTILITY OF SUCH SPECTROMETERS, SERIOUS DEFICIENCIES IN THE OPTICAL DETECTORS THAT ARE USED WITH SCINTILLATORS LIMIT THE FULL POTENTIAL OF THESE DETECTION SYSTEMS. IN CONVENTIONAL SCINTILLATION SPECTROMETERS, PHOTOMULTIPLIER TUBES ARE MOST WIDELY USED AS OPTICAL DETECTORS. UNFORTUNATELY, SUCH PHOTOMULTIPLIER TUBES HAVE LOW QUANTUM EFFICIENCY AT WAVELENGTHS CORRESPONDING TO THE EMISSIONS FROM PROMISING INORGANIC SCINTILLATORS SUCH AS THALLIUM-DOPED CESIUM IODIDE (CSI(T1)), BISMUTH GERMANATE, AND THALLIUM-DOPED SODIUM IODIDE. IN ADDITION, THE PHOTOTUBES ARE BULKY AND SHOW HIGH SENSITIVITY TO MAGNETIC FIELDS. IT HAS RECENTLY BEEN DEMONSTRATED THAT PHOTOCONDUCTIVE DETECTORS FABRICATED FROM WIDE BANDGAP SEMICONDUCTORS HAVE PRODUCED THE HIGHEST PERFORMANCE EVER ACHIEVED WITH A SCINTILLATION SYSTEM. THESE RESULTS WERE OBTAINED WITH A MERCURIC IODIDE (HGI2) PHOTODETECTOR COUPLED TO A CSI(T1) SCINTILLATOR. THIS PROGRAM WILL PRODUCE A NEW TYPE OF WIDE BANDGAP PHOTODETECTOR THAT SHOULD OFFER PERFORMANCE SUPERIOR TO THAT OF HGI2 PHOTODETECTORS AND BE USABLE UNDER A WIDE RANGE OF CONDITIONS. THESE PHOTOCONDUCTIVE DETECTORS CONSTRUCTED FROM THE WIDE BANDGAP SEMICONDUCTOR INDIUM IODIDE WOULD BE VERY USEFUL IN MANY APPLICATIONS THAT USE SCINTILLATION DETECTORS. IN PHASE I, CRYSTALS OF INDIUM IODIDE ARE BEING GROWN, CUT, AND FABRICATED INTO DEVICES. THESE ARE BEING CHARACTERIZED FOR THEIR ELECTRONIC PROPERTIES, AND THEIR PHOTORESPONSES ARE BEING MEASURED.