Present Status of the Dual-Sided Microstructured Semiconductor Neutron Detector (DS-MSND) and Instrumentation
| Autor: | Steven L. Bellinger, Taylor R. Ochs, Jacob M. Terrell, Robyn M. Hutchins, Luke C. Henson, Douglas S. McGregor, K. Scott DeMint |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Silicon 010308 nuclear & particles physics business.industry Detector chemistry.chemical_element 01 natural sciences Particle detector 030218 nuclear medicine & medical imaging 03 medical and health sciences 0302 clinical medicine Semiconductor chemistry 0103 physical sciences Neutron detection Optoelectronics Wafer Neutron business Diode |
| Zdroj: | 2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC). |
| Popis: | Dual-Sided Microstructured Semiconductor Neutron Detectors (DS-MSNDs) are continually being developed as a compact, low-power, high-efficiency alternative to 3He for thermal-neutron detection. DS-MSNDs are fabricated from 1.5-mm thick, 5 kOhm-cm resistivity, silicon wafers. Deep trenches are etched into both sides of the silicon substrate with the back-side trenches offset from the front-side trenches to eliminate neutron free streaming paths through the silicon fins. A pvp-type vertical diode is formed within the trench microstructures on both sides of the substrate. The trenches are then backfilled with 6LiF powder with powder-packing fractions as high as 55%. Incident neutrons are absorbed by 6Li atoms, which then fission and emit charged-particle reaction products that can deposit energy in the adjacent silicon fins. Electron-hole pairs created by the charged particle interactions are then drifted, and the current induced in the electrodes is integrated to form a voltage pulse that can be counted. So far, DS-MSNDs have achieved detection efficiencies as high as 69.3%. The present work describes efforts to improve the signal-to-noise ratio of the DS-MSNDs to increase the gamma-ray rejection ratio of the detectors. Silvaco TCAD simulations indicate alternative doping profiles can improve the charge-collection efficiency and produce single polarity pulses regardless of interaction location, whereas the polarity of the previously reported DS-MSND pulse was dependent on the location of the neutron interaction. Newly fabricated DS-MSNDs will be used to populate Modular Radiation Detectors (MRD) which will be integrated into a high-sensitivity Reconfigurable Wearable Detector (RWD). In addition to neutron detection, the MRDs will incorporate a high energy-resolution gamma-ray spectrometer for gamma-ray source detection and identification. The RWD will be a highly versatile, low cost, low power, tool for the search, localization, and identification of radioactive material. |
| Databáze: | OpenAIRE |
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