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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA, USA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Investigation of a Readout Circuit Design that Reduces Effective Capacitance of Large Area SiPMs
摘要： In order to provide a large photo-sensitive area, silicon photomultipliers (SiPMs) comprise thousands of Geiger-mode avalanche photodiodes (GM-APDs) connected in parallel. This results in a large device capacitance that causes R-C shaping of output signals, elongating signal rise time and reducing signal-to-noise ratio (SNR). One aspect of SiPMs that this affects is achievable single photon timing resolution (SPTR), where the increased signal rise time and reduced amplitude degrades timing jitter, according to the relationship in Equation 1. A method to reduce the effective device capacitance of silicon photosensors has previously been explored and applied to direct conversion semiconductor devices. The basic idea is that signal from the cathode is connected to the opposite side of the junction via a unity-gain amplifier to balance the AC voltages on the two sides of the detector. The result is an effective reduction in device capacitance seen by the front-end electronics used to read signal from cathode. If this technique is applied to SiPM readout, it has the potential to reduce the effective device capacitance and provide a pathway for improved timing performance.
关键词： SiPM,effective capacitance,readout circuit,timing resolution,bootstrap amplifier
更新于2025-09-04 15:30:14
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Tests and Foreseen Developments of Fibered-OSLD Gamma-Heating Measurements in Low-Power Reactors
摘要： In this paper, test measurements of a fibered optically stimulated luminescent dosimeter (OSLD) system performed during a dedicated experimental phase in EOLE zero-power reactor are presented. The measurement setup consists of an OSLD crystal connected onto the extremity of an optical fiber and a laser stimulation system, manufactured by the CEA/LIST, Saclay, France. The OSL sensor is remotely stimulated via an optical fiber using a diode-pumped solid-state laser. The OSL light is collected and guided back along the same fiber to a photomultiplier tube through appropriate optical filters. OSL signals are corrected for background noise and integrated to provide the absorbed doses thanks to calibration coefficients. The light stimulation also fully bleaches the crystal (reusable for the next measurement). Results obtained using this system are compared to usual gamma-heating measurement protocol using OSLD pellets. Both measurement processes were calibrated to ensure the comparison of absolute doses in gray at the same positions in the core. The presence of induced radioluminescence in the OSLD during the irradiation was also observed and could be used to monitor the gamma flux. The feasibility of remote measurements is achieved, whereas further developments could be conducted to improve this technique since the readout procedure still requires to withdraw the OSLD off the gamma flux (hence from the core) on account of the dose rate (around a few Gy·h?1), and the readout time remains quite long for online applications. Several improvements are foreseen and will be tested in the forthcoming years.
关键词： optically stimulated luminescent dosimeters (OSLD),optical fibers,Nuclear heating,remote readout
更新于2025-09-04 15:30:14
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Dual-ended readout small animal PET detector by using 0.5?mm pixelated LYSO crystal arrays and SiPMs
摘要： Small animal PET scanners need to have a high spatial resolution since the size of the organs of small animals is much smaller than that of humans, and also need to have a high sensitivity since the allowed injection dose is limited by the radiation dosimetry of the small organs. To simultaneously achieve high spatial resolution and high sensitivity for a small animal PET scanner, detectors with high position resolution, high efficiency and high depth of interaction (DOI) resolution are required. In this work, three 17 × 17 pixelated LYSO arrays with crystal size of ～ 0.5 mm and an outer dimension of 10 × 10 × 20 mm3 are fabricated. The first LYSO array uses 80 μm thick BaSO4 reflector. The second and the third LYSO arrays use 65 μm thick Toray reflectors. The outermost side of the third LYSO array is also wrapped with k9 glass of the same size as the crystals in the array in order to improve the light collection and flood histogram quality for the edge crystals. The LYSO arrays are read out with two Hamamatsu SiPM arrays from both ends. The SiPM array is 4 × 4, with 3 × 3 mm2 pixel size and 0.2 mm gap in between the SiPM pixels. The SiPM array is read out with a resistor network circuit to reduce the number of signals from 16 to 4. The performance of the detector in terms of flood histograms, energy resolution, DOI resolution and timing resolution was measured. All three detectors provide good flood histograms and all crystals in an array can be clearly resolved. The average DOI resolutions of individual crystals are 1.84, 1.98 and 1.93 mm for the three detectors for events with energy E > 350 keV. The BaSO4 array has higher light output and provides a better average crystal energy resolution of 21.0 %. The photopeak amplitude of the Toray arrays changes with depth, which results in worse energy resolutions of 24.4 % and 23.8 % for the two detectors respectively. The average timing resolutions of individual crystals are 1.23, 1.27 and 1.24 ns for the three detectors for events with E > 350 keV. All three detector modules achieved high position resolution (0.5 mm crystal size), high efficiency (20 mm crystal length) and high DOI resolution (<2.0 mm) and can be used to build a high sensitivity small animal PET scanner with spatial resolution approaching the physical limit.
关键词： Dual-ended readout,Small animal PET,Depth of interaction,High resolution,SiPM
更新于2025-09-04 15:30:14
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A line code with quick-resynchronization capability and low latency for the optical data links of LHC experiments
摘要： We propose a line code that has fast resynchronization capability and low latency. Both the encoder and decoder have been implemented in FPGAs. The encoder has also been implemented in an ASIC. The latency of the whole optical link (not including the optical ?ber) is estimated to be less than 73.9 ns. In the case of radiation-induced link synchronization loss, the decoder can recover the synchronization in 25 ns. The line code will be used in the ATLAS liquid argon calorimeter Phase-I trigger upgrade and can also be potentially used in other LHC experiments.
关键词： Digital electronic circuits,Trigger concepts and systems (hardware and software),Front-end electronics for detector readout
更新于2025-09-04 15:30:14
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Design of the readout electronics for the DAMPE Silicon Tracker detector
摘要： The Silicon Tracker (STK) is one of the detectors of the DAMPE satellite used to measure the incidence direction of high energy cosmic rays. It consists of 6 X-Y double layers of silicon micro-strip detectors with 73728 readout channels. It is a great challenge to read out the channels and process the huge volume of data in the harsh environment of space. 1152 Application Specific Integrated Circuits (ASIC) and 384 ADCs are used to read out the detector channels. 192 Tracker Front-end Hybrid (TFH) modules and 8 identical Tracker Readout Board (TRB) modules are designed to control and digitalize the front signals. In this paper, the design of the readout electronics for the STK and its performance are presented in detail.
关键词： silicon strip detector,readout electronics,DAMPE,VA140
更新于2025-09-04 15:30:14