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Design and characterization of small detection modules based on scintillators and WLS bars with SiPM readout for a cosmic ray mini-array
摘要： This paper describes the design and characterization tests of detection modules for a low-cost, easily reconfigurable mini-array for cosmic rays. The basic layout of each individual module is based on a 400 cm2 scintillator tile, optically coupled to a Wavelength Shifter (WLS) bar and a Silicon Photomultiplier (SiPM) for light collection and readout. Low cost solutions, based on the Arduino MEGA board, have been adopted for electronics, triggering and data acquisition, in view of the operation of this facility. The first detection modules, equipped with 4×4 mm2 SiPMs were fully built and characterized. Additional tests were also carried out with photosensors having different sensitive area and technology.
关键词： Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators),Particle detectors,Interaction of radiation with matter
更新于2025-09-23 15:23:52
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Operation and performance of microhexcavity pixel detector in gas discharge and avalanche mode
摘要： The Microhexcavity Panel (??Hex) is a novel gaseous micropattern particle detector comprised of a dense array of close-packed hexagonal pixels, each operating as an independent detection unit for ionizing radiation. It is a second generation detector derived from plasma panel detectors and microcavity detectors. The ??Hex is under development to be deployed as a scalable, fast timing (ns) and hermetically sealed gaseous tracking detector with high rate (> 100KHz∕cm2) capability. The devices reported here were fabricated as 16 × 16 pixel arrays of 2 mm edge-to-edge, 1 mm deep hexagonal cells embedded in a thin, 1.4 mm glass–ceramic wafer. Cell walls are metalized cathodes, connected to high voltage bus lines through conductive vias. Anodes are small, 457 μm diameter metal discs screen printed on the upper substrate. The detectors are filled with an operating gas to near 1 atm and then closed with a shut-off valve. They have been operated in both avalanche mode and gas discharge devices, producing mV to volt level signals with about 1 to 3 ns rise times. Operation in discharge mode is enabled by high impedance quench resistors on the high voltage bus at each pixel site. Results indicate that each individual pixel behaves as an isolated detection unit with high single pixel intrinsic efficiency to both ??s from radioactive sources and to cosmic ray muons. Continuous avalanche mode operation over several days at hit rates over 300 KHz∕cm2 with no gas flow have been observed. Measurements of pixel isolation, timing response, efficiency, hit rate and rate stability are reported.
关键词： Gas based radiation detectors,Particle detectors,Pixel detectors
更新于2025-09-23 15:21:01
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Timepix in LEO Orbit onboard the VZLUSAT-1 Nanosatellite: 1-year of Space Radiation Dosimetry Measurements
摘要： The VZLUSAT-1 satellite, the first Czech CubeSat, was successfully launched on June 23, 2017, to a 510 km Sun-synchronous low-Earth orbit. It carries several scientific payloads including a Timepix detector as focal plane imager for the X-Ray telescope onboard. The Timepix detector contributes significantly to the satellite data collection, with more than 25 000 sampling acquisitions in the first year of deployment. Despite limitations of the satellite attitude control system, necessary for capturing X-Ray images of the Sun, the Timepix detector allows measuring the space radiation environment along the satellite orbit. As of September 2018, we conducted 33 whole-Earth mappings, recording radiation doses around the planet. Further, we show data from scans of the South Atlantic Anomaly and polar radiation horns, where the location and acquisition time were tailored to minimize event pile-up and particle track overlap. Since October 2017, the optics segment of the onboard X-Ray telescope was deployed, which exposed the Timepix detector unshielded to free open space. This change produced entirely new observations namely of low energy charged particles and a significant increase of measured particle flux. We also registered the effects of exposing the sensor to direct intense sunlight. We will summarize on the actual performance of the custom readout interface, which exceeds expectations in the constrained environment of the low-cost and low-powered CubeSat nanosatellite.
关键词： Particle detectors,On-board space electronics,X-ray detectors and telescopes,Space instrumentation
更新于2025-09-23 15:21:01
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The use of optical fibers as passageways for the scintillation light produced in CaF <sub/>2</sub> (Eu) powder in water for low-level tritiated water measurement
摘要： A solid scintillation counting (SSC) system which uses the mixture of CaF2(Eu) powder and tritiated water inside the chamber room will be developed for the measurement of low-level tritiated water. However, the coincidence detection e?ciency and net count rate might be limited by the photon absorption in the chamber of the SSC detector. This paper discusses the feasibility of using light guide ?bers as the optical passageway in the chamber room by Geant4 simulation. The simulation results show that the performance of the detector can be improved by using wavelength-shifting ?bers as optical passageway in the chamber. The detector can maintain a 4.2% coincidence detection e?ciency at a 6 cm chamber thickness, and the detection limit can be as low as 0.47 Bq/mL under 10 min measurement. As a result, using wavelength-shifting ?bers as optical passageways in the chamber room of the SSC system is possible and e?ective.
关键词： Radiation monitoring,Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc),Very low-energy charged particle detectors,Solid state detectors
更新于2025-09-16 10:30:52
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Feasibility study of a proton fluence monitor for LEO-Nanosatellite missions based on displacement damage induced in GaAs-LED
摘要： High-energy protons trigger irreparable displacement damage (DD) in unbiased Gallium Arsenide (GaAs) Light-Emitting Diode GaAs-LED (GAL). The DD is caused by non-ionizing-energy-loss (NIEL) process and results in reduction of light emission of the GAL when connected to a power source. Based on this finding a lightweight, low current consuming proton detector for space applications was developed. A commercial off the shelf (COTS) yellow GAL optically coupled to a Light-to-Frequency converter chip (LFC) made the basic assembly of the proposed proton detector. The device was calibrated using selected GAL samples irradiated with a 180 MeV proton beam from a proton-therapy medical cyclotron to 2, 10, 50, 100, 200 and 300 Gy dose levels. The light output of the GAL was measured with the detector assembly and presented as frequency (kHz). Protons of energy distribution between 100 keV to ～500 MeV are trapped in the inner-shell of the Van Allen belt (VAB) surrounding the earth, whereas the intensity of trapped electrons (Emax ～10 MeV) remains insignificant. The GAL light output data (frequency) was fitted with a second-degree polynomial function of imparted proton dose (～ number of protons). The results were parameterized for widely used NASA radiation belt models AP8-Max and AP8-Min using the proton NIEL distribution in Gallium Arsenide (GaAs). Spacecrafts, in particular Nanosatellites operating in low earth orbit (LEO) environment are primarily exposed to those trapped protons in the VAB. Nanosatellites endure severe radiation exposure while passing through the South Atlantic Anomaly (SAA) region. The footprint, mass and average current consumption of the proton detector was 0.027 cm2, 0.28 g and 2.5 mA respectively. The highest detectable level proton fluence (protons·cm?2) was evaluated to be 1.17 × 109 and 1.01 × 109 for AP8-Max and AP8-Min models respectively. Hence the proposed GAL based radiation detector is only suited for proton fluence monitoring on board LEO-Nanosatellites (NanoSat) of short lifetime, usually 6–18 months.
关键词： Particle detectors,Solid state detectors,Dosimetry concepts and apparatus
更新于2025-09-12 10:27:22