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X-ray imaging demonstration of glass GEM detector with dynamic time-over-threshold-based readout
摘要： Large-scale detection is one of the important roles for gaseous detectors to play in high-energy physics. In many cases, energy resolving multi-channel readout is required. Recent micro-pattern gaseous detectors (MPGDs) have finer pitches or pixels; hence, large-sized detectors have thousands of readout channels. In those cases, it becomes important to reduce the scale and complexity of the readout circuit while keeping its energy resolving capability. The signal processing technique called dynamic time-over-threshold (dynamic ToT, dToT) achieves both the good conversion linearity from analog to digital signal and the compact circuit scale compared with conventional analog-to-digital-converter (ADC)-based readout. In this study, we developed and demonstrated a dToT-based readout circuit for glass gas electron multiplier (glass GEM, G-GEM). The readout circuit showed better linearity than that of normal ToT. We demonstrated the readout circuit by X-ray imaging with the charge-division scheme. The good linearity of the readout circuit enabled imaging over a 100 × 100 mm2 area with small distortion. We expect that the dToT-based readout would be a promising candidate for the future readout of large-scaled MPGDs.
关键词： Digital electronic circuits,Electronic detector readout concepts (gas, liquid),Analogue electronic circuits,Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc)
更新于2025-09-23 15:23:52
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Monitoring the effect of gas purification of sealed MPGDs for X-ray imaging
摘要： The response of a sealed MicroPatterned Gaseous Detector (MPGD), with an enclosed gas purification system based on getters, was monitored for several weeks. An average of 2 discharges per day was registered during the monitoring period and the charge gain varied a maximum of 15% during the more stable period. The temperature of the getters was varied from 180?C to 250?C and no significant influence was registered in the detector response. A reactivation of the getters also did not affect the charge gain, which means that their gettering rate was at full efficiency before the reactivation. However, careful attention is paid to charge gain reduction for long times of operation which can denote a loss of getters efficiency along time and the need of getter reactivation. On the other hand, turning off the getters lead to a rapid decrease in the charge gain. This allows concluding that a purification system based on getters is really effective in removing gas impurities, being a crucial component of the detection system for a sealed gaseous detector.
关键词： Gaseous detectors,Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc)
更新于2025-09-11 14:15:04
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Tomographic capabilities of the new GEM based SXR diagnostic of WEST
摘要： The tokamak WEST (Tungsten Environment in Steady-State Tokamak) will start operating by the end of 2016 as a test bed for the ITER divertor components in long pulse operation. In this context, radiative cooling of heavy impurities like tungsten (W) in the Soft X-ray (SXR) range [0.1 keV; 20 keV] is a critical issue for the plasma core performances. Thus reliable tools are required to monitor the local impurity density and avoid W accumulation. The WEST SXR diagnostic will be equipped with two new GEM (Gas Electron Multiplier) based poloidal cameras allowing to perform 2D tomographic reconstructions in tunable energy bands. In this paper tomographic capabilities of the Minimum Fisher Information (MFI) algorithm developed for Tore Supra and upgraded for WEST are investigated, in particular through a set of emissivity phantoms and the standard WEST scenario including reconstruction errors, in?uence of noise as well as computational time.
关键词： Plasma diagnostics - interferometry, spectroscopy and imaging,X-ray detectors,Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc),Radiation calculations
更新于2025-09-09 09:28:46
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Recent advances in bubble-assisted Liquid Hole-Multipliers in liquid xenon
摘要： We report on recent advances in the operation of bubble-assisted Liquid Hole-Multipliers (LHM). By con?ning a vapor bubble under or adjacent to a perforated electrode immersed in liquid xenon, we could record both radiation-induced ionization electrons and primary scintillation photons in the noble liquid. Four types of LHM electrodes were investigated: a THGEM, standard double-conical GEM, 50 μm-thick single-conical GEM (SC-GEM) and 125 μm-thick SC-GEM — all coated with CsI photocathodes. The 125 μm-thick SC-GEM provided the highest electroluminescence (EL) yields, up to ～ 400 photons per electron over 4π, with an RMS pulse-height resolution reaching 5.5% for events comprising ～ 7000 primary electrons. Applying a high transfer ?eld across the bubble, the EL yield was further increased by a factor of ～ 5. The feasibility of a vertical-mode LHM, with the bubble con?ned between two vertical electrodes, and the operation of a two-stage LHM con?guration were demonstrated for the ?rst time. We combine electrostatic simulations with observed signals to draw conclusions regarding the location of the liquid-gas interface and suggest an explanation for the observed di?erences in EL yield between the investigated electrodes.
关键词： Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc),Noble liquid detectors (scintillation, ionization, double-phase),Charge transport, multiplication and electroluminescence in rare gases and liquids
更新于2025-09-09 09:28:46