- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Induced Charge Fluctuations in Semiconductor Detectors with a Cylindrical Geometry
摘要： Now, compound semiconductors are very appealing for hard X-ray room-temperature detectors for medical and astrophysical applications. Despite the attractive properties of compound semiconductors, such as high atomic number, high density, wide band gap, low chemical reactivity and long-term stability, poor hole and electron mobility-lifetime products degrade the energy resolution of these detectors. The main objective of the present study is in development of a mathematical model of the process of the charge induction in a cylindrical geometry with accounting for the charge carrier trapping. The formulae for the moments of the distribution function of the induced charge and the formulae for the mean amplitude and the variance of the signal at the output of the semiconductor detector with a cylindrical geometry were derived. It was shown that the power series expansions of the detector amplitude and the variance in terms of the inverse bias voltage allow determining the Fano factor, electron mobility lifetime product, and the nonuniformity level of the trap density of the semiconductor material.
关键词： cylindrical geometry,compound semiconductors,energy resolution,charge carriers trapping,charge induction
更新于2025-09-23 15:23:52
-
Operando observation of chemical transformations of iridium oxide during photoelectrochemical water oxidation
摘要： Iridium oxide is one of the few catalysts capable of catalyzing the oxygen evolution reaction (OER) in both acidic and basic conditions. Understanding the mechanism of IrOx under realistic photoelectrochemical conditions is important for the development of integrated water splitting systems. Herein, we have developed a highly efficient OER photoanode in pH 1 aqueous solutions based on a sputtered IrOx film and a p+n-Si light absorber, interfaced with sputtered Au layer. Operando high energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD XAS) was employed to monitor the oxidation state changes of IrOx during both electrochemical and photoelectrochemical (PEC) water oxidation reactions in pH 1 aqueous solutions. We observed a gradual increase of the average oxidation state of Ir with increasing anodic potential in the pre-catalytic region, followed by a reduction of Ir under O2 evolution conditions. Consistent results were obtained on dark anodes and illuminated photoanodes. However, when the thickness of IrO2 was increased to 2 and 3 nm, the spectral changes became much less pronounced and the reduction of Ir oxidation state after the OER onset was not observed. This is due to the lower surface to bulk ratio, where lattice oxygen sites in the bulk are not accessible for the formation of hydroxide. More generally, the operando method developed here can be extended to other materials, thereby providing a powerful tool for mechanism discovery and an enabling capability for catalyst design.
关键词： oxygen evolution reaction (OER),electrochemical and photoelectrochemical (PEC),high energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD XAS),iridium oxide,Operando method
更新于2025-09-23 15:23:52
-
Study of energy and timing characteristics of 38.1mm?×?38.1mm CeBr3 scintillator detectors
摘要： We report the results of measurements and GEANT4 simulation for the performance of two 38.1mm × 38.1mm CeBr3 detectors. The linearity and energy resolution of both the detectors have been measured using low energy gamma sources in the range from 121.8 keV to 4.44 MeV. Maintaining the energy linearity condition, the best time resolution value of 423 ± 14 ps was measured for 1173–1332 keV photon pair from a 60Co source. A GEANT4 simulation was performed to reproduce the measured experimental spectrum and to estimate the absolute photopeak efficiencies at several energies up to 4.44 MeV.
关键词： Time resolution,GEANT4 simulation,Energy resolution,Scintillator,CeBr3
更新于2025-09-23 15:22:29
-
[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Compact Solid State Neutron-Gamma Detectors for Backpack or Handheld Instruments
摘要： In this paper, we report on the characterization of detectors constructed at RMD using 1-inch, 1.5-inch, and 2-inch diameter right cylinders of CLYC and CLLBC crystals coupled to arrays of silicon photomultipliers (SiPM). Detectors constructed with small volume CLLBC crystals coupled to a 12 mm × 12mm total area SiPM array show an excellent energy resolution of ~3% at 662 keV and a large volume CLYC crystal when coupled to a 24 mm × 24 mm area array shows an energy resolution of ~6.6% at 662 keV. Both detectors show pulse shape discrimination capabilities.
关键词： Gamma-ray detection,crystal growth,elpasolites,energy resolution,neutron detection,scintillation detector,CLLBC,CLYC,thermal neutrons
更新于2025-09-23 15:22:29
-
Use of YAP(Ce) in the development of high spatial resolution radiation imaging detectors
摘要： A scintillator with a high light output is considered to be required for the development of high spatial resolution radiation imaging detectors. In contrast to this scientific consensus, we found that high spatial resolution images can be obtained using a medium light output scintillator comprising cerium-doped yttrium aluminum perovskite, YA1O3 (YAP(Ce)). We evaluated the performance of a radiation imaging detector comprising a 0.5 mm thick YAP(Ce) plate, which was optically coupled to a 25.4 mm (1-inch) square position-sensitive photomultiplier. The Anger principle was used to calculate the radiation positions. The spatial resolution and energy resolution for the imaging detector with 5.5 MeV alpha particles were 0.2 mm full width at half-maximum (FWHM) and 7.4% FWHM, respectively. The spatial resolutions for 60 keV gamma photons and ~32 keV X-rays were ~ 0.6 mm FWHM and ~ 0.8 mm FWHM, respectively. The spatial resolution of the detector when imaging beta particles at a maximum energy of 254 keV was less than 0.6 mm FWHM. We conclude that YAP(Ce) is a promising scintillator for developing high spatial resolution and high energy resolution radiation detectors for imaging alpha particles, beta particles, and gamma photons.
关键词： YAP(Ce),energy resolution,position-sensitive photomultiplier,spatial resolution
更新于2025-09-23 15:21:21
-
High-selectivity bandpass filter using six pairs of quarter-wavelength coupled lines
摘要： We present a 16-channel readout integrated circuit (ROIC) with nanosecond-resolution time to digital converter (TDC) for pixelated Cadmium Telluride (CdTe) gamma-ray detectors. The pixel array ROIC is the proof of concept of the pixel array readout ASIC for positron-emission tomography (PET) scanner, positron-emission mammography (PEM) scanner, and Compton gamma camera. The electronics of each individual pixel integrates an analog front-end with switchable gain, an analog to digital converter (ADC), configuration registers, and a 4-state digital controller. For every detected photon, the pixel electronics provides the energy deposited in the detector with 10-bit resolution, and a fast trigger signal for time stamp. The ASIC contains the 16-pixel matrix electronics, a digital controller, five global voltage references, a TDC, a temperature sensor, and a band-gap based current reference. The ASIC has been fabricated with TSMC m mixed-signal CMOS technology and occupies an area of mm. The TDC shows a resolution mm of 95.5 ps, a precision of 600 ps at full width half maximum W. In acquisition (FWHM), and a power consumption of mode, the total power consumption of every pixel is W. An equivalent noise charge (ENC) of at maximum gain and negative polarity conditions has been measured at room temperature.
关键词： positron emission tomography,low-power electronics,semiconductor radiation detectors,application specific integrated circuits,gamma-ray detectors,Analog-digital conversion,energy resolution
更新于2025-09-23 15:21:01
-
[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Doped Layer Characterization Using Accurate Optical Modelling of Mid-Infrared Spectrometry
摘要： We present a 16-channel readout integrated circuit (ROIC) with nanosecond-resolution time to digital converter (TDC) for pixelated Cadmium Telluride (CdTe) gamma-ray detectors. The pixel array ROIC is the proof of concept of the pixel array readout ASIC for positron-emission tomography (PET) scanner, positron-emission mammography (PEM) scanner, and Compton gamma camera. The electronics of each individual pixel integrates an analog front-end with switchable gain, an analog to digital converter (ADC), con?guration registers, and a 4-state digital controller. For every detected photon, the pixel electronics provides the energy deposited in the detector with 10-bit resolution, and a fast trigger signal for time stamp. The ASIC contains the 16-pixel matrix electronics, a digital controller, ?ve global voltage references, a TDC, a temperature sensor, and a band-gap based current reference. The ASIC has been fabricated with TSMC m mixed-signal CMOS technology and occupies an area of mm. The TDC shows a resolution mm of 95.5 ps, a precision of 600 ps at full width half maximum W. In acquisition (FWHM), and a power consumption of mode, the total power consumption of every pixel is W. An equivalent noise charge (ENC) of at maximum gain and negative polarity conditions has been measured at room temperature.
关键词： positron emission tomography,low-power electronics,application speci?c integrated circuits,semiconductor radiation detectors,gamma-ray detectors,Analog-digital conversion,energy resolution
更新于2025-09-23 15:21:01
-
[IEEE 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Guangzhou, China (2019.5.19-2019.5.22)] 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Surface Waveguide Leaky-wave Antenna for Single-Side Beam Scanning
摘要： We present a 16-channel readout integrated circuit (ROIC) with nanosecond-resolution time to digital converter (TDC) for pixelated Cadmium Telluride (CdTe) gamma-ray detectors. The pixel array ROIC is the proof of concept of the pixel array readout ASIC for positron-emission tomography (PET) scanner, positron-emission mammography (PEM) scanner, and Compton gamma camera. The electronics of each individual pixel integrates an analog front-end with switchable gain, an analog to digital converter (ADC), configuration registers, and a 4-state digital controller. For every detected photon, the pixel electronics provides the energy deposited in the detector with 10-bit resolution, and a fast trigger signal for time stamp. The ASIC contains the 16-pixel matrix electronics, a digital controller, five global voltage references, a TDC, a temperature sensor, and a band-gap based current reference. The ASIC has been fabricated with TSMC m mixed-signal CMOS technology and occupies an area of mm. The TDC shows a resolution mm of 95.5 ps, a precision of 600 ps at full width half maximum W. In acquisition (FWHM), and a power consumption of mode, the total power consumption of every pixel is W. An equivalent noise charge (ENC) of at maximum gain and negative polarity conditions has been measured at room temperature.
关键词： gamma-ray detectors,low-power electronics,Analog-digital conversion,semiconductor radiation detectors,application specific integrated circuits,positron emission tomography,energy resolution
更新于2025-09-23 15:19:57
-
High resolution time- and angle-resolved photoemission spectroscopy with 11 eV laser pulses
摘要： Performing time- and angle-resolved photoemission (tr-ARPES) spectroscopy at high momenta necessitates extreme ultraviolet laser pulses, which are typically produced via high harmonic generation (HHG). Despite recent advances, HHG-based setups still require large pulse energies (from hundreds of μJ to mJ) and their energy resolution is limited to tens of meV. Here, we present a novel 11 eV tr-ARPES setup that generates a flux of 5 × 1010 photons/s and achieves an unprecedented energy resolution of 16 meV. It can be operated at high repetition rates (up to 250 kHz) while using input pulse energies down to 3 μJ. We demonstrate these unique capabilities by simultaneously capturing the energy and momentum resolved dynamics in two well-separated momentum space regions of a charge density wave material ErTe3. This novel setup offers the opportunity to study the non-equilibrium band structure of solids with exceptional energy and time resolutions at high repetition rates.
关键词： energy resolution,time- and angle-resolved photoemission spectroscopy,HHG,tr-ARPES,charge density wave,high repetition rates,high harmonic generation,ErTe3,11 eV laser pulses
更新于2025-09-23 15:19:57
-
[IEEE 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Sydney, Australia (2018.11.10-2018.11.17)] 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC) - Comparison of NaI coupled to photomultiplier tube and silicon photomultiplier
摘要： The NaI scintillator has been widely used for decades. In recent years, the silicon photomultiplier (SiPM), a new photosensor based on semiconductor technologies, has attracted a great deal of attention and has started replacing the conventional photomultiplier tube (PMT) in some applications. This work compares the performance of two NaI detectors with the same size crystals in which one is coupled to a PMT and the other is coupled to a SiPM array. The response of both detectors is fairly linear although the NaI-SiPM detector shows signs of saturation for high energy gammas. The waveform and the energy resolution of the detectors are studied for temperatures between –20 and 50°C. Because of the capacitance of the SiPMs, the decay constant of the waveform for the NaI-SiPM detector is signi?cantly longer than that for the NaI-PMT detector. The energy resolution for both detectors changes with temperatures for a ?xed shaping time. However, with a proper choice of the shaping time according to the temperature, the energy resolution for the NaI-SiPM detector is as good as the NaI-PMT detector.
关键词： NaI scintillator,silicon photomultiplier (SiPM),energy resolution,photomultiplier tube (PMT),temperature dependence
更新于2025-09-16 10:30:52