Formamidinium lead iodide(FAPbI_(3))perovskite exhibits an impressive X-ray absorption coefficient and a large carrier mobility-lifetime product(μτ),making it as a highly promising candidate for X-ray detection appl...Formamidinium lead iodide(FAPbI_(3))perovskite exhibits an impressive X-ray absorption coefficient and a large carrier mobility-lifetime product(μτ),making it as a highly promising candidate for X-ray detection application.However,the presence of larger FA^(+)cation induces to an expansion of the Pb-I octahedral framework,which unfortunately affects both the stability and charge carrier mobility of the corresponding devices.To address this challenge,we develop a novel low-dimensional(HtrzT)PbI_(3) perovskite featuring a conjugated organic cation(1H-1,2,4-Triazole-3-thiol,HtrzT^(+))which matches well with theα-FAPbI_(3) lattices in two-dimensional plane.Benefiting from the matched lattice between(HtrzT)PbI_(3) andα-FAPbI_(3),the anchored lattice enhances the Pb-I bond strength and effectively mitigates the inherent tensile strain of theα-FAPbI_(3) crystal lattice.The X-ray detector based on(HtrzT)PbI_(3)(1.0)/FAPbI_(3) device achieves a remarkable sensitivity up to 1.83×10^(5)μC Gy_(air)^(−1) cm^(−2),along with a low detection limit of 27.6 nGy_(air) s^(−1),attributed to the release of residual stress,and the enhancement in carrier mobility-lifetime product.Furthermore,the detector exhibits outstanding stability under X-ray irradiation with tolerating doses equivalent to nearly 1.17×10^(6) chest imaging doses.展开更多
The PICOSEC Micromegas(MM)is a precise timing gaseous detector based on a Cherenkov radiator coupled with a semi-transparent photocathode and an MM amplifying structure.It features a two-stage amplification process th...The PICOSEC Micromegas(MM)is a precise timing gaseous detector based on a Cherenkov radiator coupled with a semi-transparent photocathode and an MM amplifying structure.It features a two-stage amplification process that leads to a significant deterioration of non-uniformity when scaling up to larger areas.Since the performance of gaseous detectors is highly dependent on the choice of working gas,optimizing the gas mixture offers a promising solution to improve the uniformity performance.This paper addresses these challenges through a combined approach of simulation based on Garfield++and experimental studies.The simulation investigates the properties of different mixing fractions of gas mixtures and their impact on detector performance,including gain uniformity and time resolution.To verify the simulation results,experimental tests were conducted using a multi-channel PICOSEC MM prototype with different gas mixtures.The experimental results are consistent with the findings of the simulation,indicating that a higher concentration of neon significantly improves the detector’s gain uniformity.Furthermore,the influence of gas mixtures on time resolution was explored as a critical performance indicator.The study presented in this paper offers valuable insights for improving uniformity in large-area PICOSEC MM detectors and optimizing overall performance.展开更多
Founded in 2009,the China Dark Matter Experiment(CDEX)collaboration was dedicated to the detection of dark matter(DM)and neutrinoless double beta decay using high-purity germanium(HPGe)detectors in the China Jinping U...Founded in 2009,the China Dark Matter Experiment(CDEX)collaboration was dedicated to the detection of dark matter(DM)and neutrinoless double beta decay using high-purity germanium(HPGe)detectors in the China Jinping Underground Laboratory.HPGe detectors are characterized by a high energy resolution,low analysis threshold,and low radioactive background,making them an ideal platform for the direct detection of DM.Over the years,CDEX has accumulated a massive amount of experimental data,based on which various results on DM detection and neutrinoless double beta decay have been presented.Because the dataset was collected in a low-background environment,apart from the analysis of DM-related physical channels,it has great potential as an indicator in other rare physical events searches.Furthermore,by providing raw pulse shapes,the dataset can serve as a tool for effectively understanding the internal mechanisms of HPGe detectors.展开更多
Quantum key distribution(QKD)is recognized as an unconditionally secure method of communication encryption,relying solely on the principles of quantum mechanics.A key performance metric for QKD systems is secure key r...Quantum key distribution(QKD)is recognized as an unconditionally secure method of communication encryption,relying solely on the principles of quantum mechanics.A key performance metric for QKD systems is secure key rate(SKR),which is a critical factor for real-world applications.Herein,we report a practical QKD system,equipped with compact gated InGaAs/InP single-photon detectors(SPDs),that can generate a high SKR of 15.2 Mb/s with a channel loss of 2 dB.This exceptional performance stems from the ultra-low afterpulsing probability of the SPDs,which significantly reduces the bit error rate in the QKD system.The typical quantum bit error rate is 1.3%.The results validate the feasibility of an integrated,practical QKD system and offer a reliable solution for the future development of real-world QKD networks.展开更多
Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in 2021.The pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μm...Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in 2021.The pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μm.The array is divided into 16 subarrays,with pixels of 400 rows×32 columns per subarray.Each pixel incorporates two charge sensors:a diode sensor and a Topmetal sensor.The in-pixel circuit primarily consists of a charge-sensitive amplifier for energy measurements,a discriminator with a peak-holding circuit,and a time-to-amplitude converter for time-of-arrival measurements.The pixel of Topmetal-M2 has a charge input range of~0-3 k e-,a voltage output range of~0-180 mV,and a charge-voltage conversion gain of~59.56μV∕e-.The average equivalent noise charge of Topmetal-M2,which includes the readout electronic system noise,is~43.45 e-.In the scanning mode,the time resolution of Topmetal-M2 is 1 LSB=1.25μs,and the precision is^()7.41μs.At an operating voltage of 1.5 V,Topmetal-M2 has a power consumption of~49 mW∕cm~2.In this article,we provide a comprehensive overview of the chip architecture,pixel working principles,and functional behavior of Topmetal-M2.Furthermore,we present the results of preliminary tests conducted on Topmetal-M2,namely,alpha-particle and soft X-ray tests.展开更多
The polarization properties of light are widely applied in imaging,communications,materials analy⁃sis,and life sciences.Various methods have been developed that can measure the polarization information of a target.How...The polarization properties of light are widely applied in imaging,communications,materials analy⁃sis,and life sciences.Various methods have been developed that can measure the polarization information of a target.However,conventional polarization detection systems are often bulky and complex,limiting their poten⁃tial for broader applications.To address the challenges of miniaturization,integrated polarization detectors have been extensively explored in recent years,achieving significant advancements in performance and functionality.In this review,we focus mainly on integrated polarization detectors with innovative features,including infinitely high polarization discrimination,ultrahigh sensitivity to polarization state change,full Stokes parameters measure⁃ment,and simultaneous perception of polarization and other key properties of light.Lastly,we discuss the oppor⁃tunities and challenges for the future development of integrated polarization photodetectors.展开更多
The measurement of low-level radioactivity using high-purity germanium(HPGe)detectors is important in applications such as environmental background radiation,material screening,and rare decays.The dead layers,dead zon...The measurement of low-level radioactivity using high-purity germanium(HPGe)detectors is important in applications such as environmental background radiation,material screening,and rare decays.The dead layers,dead zones,aluminum shell thickness,and diameter of Ge crystals are the most influential factors affecting the performance of HPGe detectors;hence,precise modeling of the physical conditions of the detectors is highly desirable.In this study,the GEANT4 simulation framework with an optimized detector geometry adequately replicated the experimentally recorded spectrum.These detector simulations explored the idea of realizing a dead zone(an inactive volume)at the backend of an n-type coaxial Gecrystal.Using multigamma sources,the effect of true coincidence summing(TCS)on the full energy peak(FEP)efficiency calibration of an HPGe detector was investigated as a function of sample-to-detector distance.Good agreements between the simulated and experimental efficiencies as well as the simulated and analytically calculated summing coincidence correction coefficients were achieved.At a short distance between the source and detector,calculating the correction factors for a strong source posed challenges owing to significant deadtime and pile-up effects of the detection system.The described methodology can efficiently determine summing peak probabilities at short sample-to-detector distances.展开更多
Quantum key distribution(QKD)achieves information-theoretic security based on quantum mechanics principles,where single-photon detectors(SPDs)serve as critical components.This study focuses on the sinusoidal gated SPD...Quantum key distribution(QKD)achieves information-theoretic security based on quantum mechanics principles,where single-photon detectors(SPDs)serve as critical components.This study focuses on the sinusoidal gated SPDs widely used in high-speed QKD systems.We investigate the mechanisms underlying the rising-edge jitter in detection signals,identifying contributions from factors such as the temporal width of injected optical pulses,avalanche generation processes,avalanche signal extraction,and pulse discrimination.To address the issue of excessive jitter-induced bit errors,we propose a retiming scheme that utilizes coincidence signals synchronized with the sinusoidal gating signal.This approach effectively suppresses detection signal jitter and reduces the after-pulse probability of the detector.Experimental validation using a high-precision time-to-digital converter(TDC)demonstrates a significant reduction in the rising-edge jitter distribution after applying the suppression scheme.The proposed method features clear principles and straightforward engineering implementation,avoiding direct interference with the detector’s operational processes.The designed high-speed sinusoidal gated InGaAs/InP SPD operates at 1.25 GHz,achieving a remarkable reduction in after-pulse probability from 10.7%(without jitter suppression)to 0.72%,thereby enhancing the overall performance of QKD systems.展开更多
Self-powered neutron detectors(SPNDs)play a critical role in monitoring the safety margins and overall health of reactors,directly affecting safe operation within the reactor.In this work,a novel fault identification ...Self-powered neutron detectors(SPNDs)play a critical role in monitoring the safety margins and overall health of reactors,directly affecting safe operation within the reactor.In this work,a novel fault identification method based on graph convolutional networks(GCN)and Stacking ensemble learning is proposed for SPNDs.The GCN is employed to extract the spatial neighborhood information of SPNDs at different positions,and residuals are obtained by nonlinear fitting of SPND signals.In order to completely extract the time-varying features from residual sequences,the Stacking fusion model,integrated with various algorithms,is developed and enables the identification of five conditions for SPNDs:normal,drift,bias,precision degradation,and complete failure.The results demonstrate that the integration of diverse base-learners in the GCN-Stacking model exhibits advantages over a single model as well as enhances the stability and reliability in fault identification.Additionally,the GCN-Stacking model maintains higher accuracy in identifying faults at different reactor power levels.展开更多
SiGe offers a low-cost alternative to conventional infrared sensor material systems such as InGaAs, InSb, and HgCdTe for developing near-infrared (NIR) photodetector devices that do not require cooling and can operate...SiGe offers a low-cost alternative to conventional infrared sensor material systems such as InGaAs, InSb, and HgCdTe for developing near-infrared (NIR) photodetector devices that do not require cooling and can operate with relatively low dark current. As a result of the significant difference in thermal expansion coefficients between germanium (Ge) and silicon (Si), tensile strain incorporated into SiGe detector devices through specialized growth processes can extend their NIR wavelength range of operation. We have utilized high throughput, large-area complementary metal-oxide semiconductor (CMOS) technology to fabricate Ge based p-i-n (PIN) detector devices on 300 mm Si wafers. The two-step device fabrication process, designed to effectively reduce the density of defects and dislocations arising during deposition that form recombination centers which can result in higher dark current, involves low temperature epitaxial deposition of Ge to form a thin p<sup>+</sup> seed layer, followed by higher temperature deposition of a thicker Ge intrinsic layer. Phosphorus was then ion-implanted to create devices with n<sup>+</sup> regions of various doping concentrations. Secondary ion mass spectroscopy (SIMS) has been utilized to determine the doping profiles and material compositions of the layers. In addition, electrical characterization of the I-V photoresponse of different devices from the same wafer with various n<sup>+</sup> region doping concentrations has demonstrated low dark current levels (down to below 1 nA at -1 V bias) and comparatively high photocurrent at reverse biases, with optimal response for doping concentration of 5 × 10<sup>19</sup> cm<sup>-3</sup>.展开更多
Photon counting detectors(PCDs) have attained w ide use in X-ray imaging for various preclinical and clinical applications in the past decade. This paper briefly review s the preclinical and clinical applications of P...Photon counting detectors(PCDs) have attained w ide use in X-ray imaging for various preclinical and clinical applications in the past decade. This paper briefly review s the preclinical and clinical applications of PCDs based X-ray imaging systems.Starting with an introduction of X-ray single photon detection mechanism,the brief review first describes tw o major advantages of utilizing PCDs: photon energy resolving capability and electronic noise elimination. Compared to energy integrating detectors(EIDs),the aforementioned advantages make PCDs more favorable in X-ray imaging with profound benefits such as enhanced tissue contrast,decreased image noise,increased signal to noise ratio,decreased radiation dose to the small animals and patients,and more accurate material decomposition. The utilizations of PCDs in X-ray projection radiography and computed tomography(CT)including micro-CT,dedicated breast CT,K-edge CT,and clinical CT are then review ed for the imaging applications ranging from phantoms to small animals and humans. In addition,optimization methods aiming to improve the imaging performance using PCDs are briefly review ed. PCDs are not flaw less though,and their limitations are also discussed in this review. Nevertheless,PCDs may continuously contribute to the advancement of X-ray imaging techniques in future preclinical and clinical applications.展开更多
Ultraviolet(UV) photodetectors based on wide band gap semiconductor have attracted much attention for their small volume, low working voltage, long lifetime, good chemical and thermal stability. Up to now, many resear...Ultraviolet(UV) photodetectors based on wide band gap semiconductor have attracted much attention for their small volume, low working voltage, long lifetime, good chemical and thermal stability. Up to now, many researches have been done on the semiconductors based UV detectors and some kinds of detectors have been made, such as metal–semiconductor–metal(MSM), Schottky, and PIN-type detectors. However, the sensitivity values of those detectors are still far from the expectation. Recent years, surface plasmon(SP) has been considered to be an effective way to enhance the sensitivity of semiconductor based UV photodetector. When the light is matched with the resonance frequency of surface plasmon, the localized field enhancement or scattering effect will happen and thus the spectral response will be enhanced.Here, we present an overview of surface plasmon enhancing the performance of UV detectors, including the GaN, ZnO,and other wide band gap semiconductor UV detectors. Both fundamental and experimental achievements are contained in this review.展开更多
The charge readout of a liquid xenon(LXe)detector via proportional scintillation in the liquid phase was first realized by the Waseda group 40 years ago,but the technical challenges involved were overwhelming.Although...The charge readout of a liquid xenon(LXe)detector via proportional scintillation in the liquid phase was first realized by the Waseda group 40 years ago,but the technical challenges involved were overwhelming.Although the tests were successful,this method was finally discarded and eventually nearly forgotten.Currently,this approach is not considered for large LXe dark matter detectors.Instead,the dual-phase technology was selected despite many limitations and challenges.In two independent studies,two groups from Columbia University and Shanghai Jiao Tong University reevaluated proportional scintillation in the liquid phase.Both studies established the merits for very large LXe detectors,but the Columbia group also encountered apparent limitations,namely the shadowing of the light by the anode wires,and a dependence of the pulse shape on the drift path of the electrons in the anode region.The differences between the two studies,however,are not intrinsic to the technique,but a direct consequence of the chosen geometry.Taking the geometrical differences into account,the results match without ambiguity.They also agree with the original results from the Waseda group.展开更多
It is of particular interest to investigate nuclear fusion reactions generated by high-intensity lasers in plasma environments that are similar to real astrophysical conditions.We have experimentally investigated2H(d,...It is of particular interest to investigate nuclear fusion reactions generated by high-intensity lasers in plasma environments that are similar to real astrophysical conditions.We have experimentally investigated2H(d,p)3H,one of the most crucial reactions in big bang nucleosynthesis models,at the Shenguang-Ⅱlaser facility.In this work,we present a new calibration of CR-39 solidstate track detectors,which are widely employed as the main diagnostics in this type of fusion reaction experiment.We measure the dependence of the track diameter on the proton energy.It is found that the track diameters of protons with different energies are likely to be identical.We propose that in this case,the energy of the reaction products can be obtained by considering both the diameters and gray levels of these tracks.The present results would be very helpful for analyzing the2 H(d,p)3H reaction products recorded with the same batch of CR-39 solid-state track detectors.展开更多
In the present work, we designed the new type of photonic crystals (PCs) as reflectors. Reflections from single layer of Al2O3/MgO PC help us in recapturing the light that does escape from the scintillation surface. P...In the present work, we designed the new type of photonic crystals (PCs) as reflectors. Reflections from single layer of Al2O3/MgO PC help us in recapturing the light that does escape from the scintillation surface. Photonic crystals in one dimension array of Al2O3 and MgO with silver at periodicities N = 1, 2 and 3 were used as a reflector around the surface of the scintillation volume. Scintillation detectors are widely used in nuclear medicine. The efficiency is an important parameter for characterizing the capability of the detectors. The counting efficiency of the detectors depends on the light emission induced by radiation. The light then was converted by the photomultiplier tube into electrical pulses. The efficiency may increase by an amount of 1.64% if MgO-Ag photonic crystals are used at periodicity N = 1 as a reflector.展开更多
Several Constant False Alarm Rate （CFAR） architectures, where radar systems often employ them to automatically adapt the detection threshold to the local background noise or clutter power in an attempt to maintain a...Several Constant False Alarm Rate （CFAR） architectures, where radar systems often employ them to automatically adapt the detection threshold to the local background noise or clutter power in an attempt to maintain an approximately constant rate of false alarm, have been recently proposed to estimate the unknown noise power level. Since the Ordered-Statistics （OS） based algorithm has some advantages over the Cell-Averaging （CA） technique, we are concerned here with this type of CFAR detectors. The Linearly Combined Ordered-Statistic （LCOS） processor, which sets threshold by processing a weighted ordered range samples within finite moving window, may actually perform somewhat better than the conventional OS detector. Our objective in this paper is to analyze the LCOS processor along with the conventional OS scheme for the case where the radar receiver incorporates a postdetection integrator amongst its contents and where the operating environments contain a number of secondary interfering targets along with the primary target of concern and the two target types fluctuate in accordance with the Swerling Ⅱ fluctuation model and to compare their performances under various operating conditions.展开更多
Metal-halide perovskites are revolutionizing the world of X-ray detectors,due to the development of sensitive,fast,and cost-effective devices.Self-powered operation,ensuring portability and low power consumption,has a...Metal-halide perovskites are revolutionizing the world of X-ray detectors,due to the development of sensitive,fast,and cost-effective devices.Self-powered operation,ensuring portability and low power consumption,has also been recently demonstrated in both bulk materials and thin films.However,the signal stability and repeatability under continuous X-ray exposure has only been tested up to a few hours,often reporting degradation of the detection performance.Here it is shown that self-powered direct X-ray detectors,fabricated starting from a FAPbBr_(3)submicrometer-thick film deposition onto a mesoporous TiO_(2)scaffold,can withstand a 26-day uninterrupted X-ray exposure with negligible signal loss,demonstrating ultra-high operational stability and excellent repeatability.No structural modification is observed after irradiation with a total ionizing dose of almost 200 Gy,revealing an unexpectedly high radiation hardness for a metal-halide perovskite thin film.In addition,trap-assisted photoconductive gain enabled the device to achieve a record bulk sensitivity of 7.28 C Gy^(−1)cm^(−3)at 0 V,an unprecedented value in the field of thin-film-based photoconductors and photodiodes for“hard”X-rays.Finally,prototypal validation under the X-ray beam produced by a medical linear accelerator for cancer treatment is also introduced.展开更多
A type of Si-based blocked impurity band photoelectric detector with a planar architecture is designed and demonstrated by a modified silicon semiconductor processing technique.In this route,multiple ion implantation ...A type of Si-based blocked impurity band photoelectric detector with a planar architecture is designed and demonstrated by a modified silicon semiconductor processing technique.In this route,multiple ion implantation is utilized to ensure the uniform distribution of the P elements in silicon,and rapid thermal annealing treatment is used to activate the P atoms and reduce damages caused by ion-implantation.The fabricated prototype device exhibits an excellent photoelectric response performance.With a direct current(DC)bias voltage of-2.3 V,the device detectivity to blackbody irradiation is as high as 5×10^(13)cm·Hz^(1/2)/W,which corresponds to a device responsivity of nearly 4.6 A/W,showing their potential applications in infrared detection,infrared astrophysics,and extraterrestrial life science.In particular,the developed device preparation process is compatible with that for the CMOS-circuit,which greatly reduces the manufacturing cost.展开更多
Resonant-mass gravitational wave detectors are reviewed from the concept of gravitational waves and its mathematical derivation, using Einstein＇s general relativity, to the present status of bars and spherical detect...Resonant-mass gravitational wave detectors are reviewed from the concept of gravitational waves and its mathematical derivation, using Einstein＇s general relativity, to the present status of bars and spherical detectors, and their prospects for the future, which include dual detectors and spheres with non-resonant transducers. The review not only covers technical aspects of detectors and sciences that will be done, but also analyzes the subject in a historical perspective, covering the various detection efforts over four decades, starting from Weber＇s pioneering work.展开更多
High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were ...High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.展开更多
基金supports from the National Natural Science Foundation of China(22375220,U2001214,22471302)the Guangdong Basic and Applied Basic Research Foundation(2024B1515020101)Open Project Fund from State Key Laboratory of Optoelectronic Materials and Technologies(OEMT-2024-KF-08).
文摘Formamidinium lead iodide(FAPbI_(3))perovskite exhibits an impressive X-ray absorption coefficient and a large carrier mobility-lifetime product(μτ),making it as a highly promising candidate for X-ray detection application.However,the presence of larger FA^(+)cation induces to an expansion of the Pb-I octahedral framework,which unfortunately affects both the stability and charge carrier mobility of the corresponding devices.To address this challenge,we develop a novel low-dimensional(HtrzT)PbI_(3) perovskite featuring a conjugated organic cation(1H-1,2,4-Triazole-3-thiol,HtrzT^(+))which matches well with theα-FAPbI_(3) lattices in two-dimensional plane.Benefiting from the matched lattice between(HtrzT)PbI_(3) andα-FAPbI_(3),the anchored lattice enhances the Pb-I bond strength and effectively mitigates the inherent tensile strain of theα-FAPbI_(3) crystal lattice.The X-ray detector based on(HtrzT)PbI_(3)(1.0)/FAPbI_(3) device achieves a remarkable sensitivity up to 1.83×10^(5)μC Gy_(air)^(−1) cm^(−2),along with a low detection limit of 27.6 nGy_(air) s^(−1),attributed to the release of residual stress,and the enhancement in carrier mobility-lifetime product.Furthermore,the detector exhibits outstanding stability under X-ray irradiation with tolerating doses equivalent to nearly 1.17×10^(6) chest imaging doses.
基金supported by the National Natural Science Foundation of China(12125505).
文摘The PICOSEC Micromegas(MM)is a precise timing gaseous detector based on a Cherenkov radiator coupled with a semi-transparent photocathode and an MM amplifying structure.It features a two-stage amplification process that leads to a significant deterioration of non-uniformity when scaling up to larger areas.Since the performance of gaseous detectors is highly dependent on the choice of working gas,optimizing the gas mixture offers a promising solution to improve the uniformity performance.This paper addresses these challenges through a combined approach of simulation based on Garfield++and experimental studies.The simulation investigates the properties of different mixing fractions of gas mixtures and their impact on detector performance,including gain uniformity and time resolution.To verify the simulation results,experimental tests were conducted using a multi-channel PICOSEC MM prototype with different gas mixtures.The experimental results are consistent with the findings of the simulation,indicating that a higher concentration of neon significantly improves the detector’s gain uniformity.Furthermore,the influence of gas mixtures on time resolution was explored as a critical performance indicator.The study presented in this paper offers valuable insights for improving uniformity in large-area PICOSEC MM detectors and optimizing overall performance.
基金supported by the National Key Research and Development Program of China(Nos.2023YFA1607100 and 2022YFA1605000)the National Natural Science Foundation of China(No.12322511)。
文摘Founded in 2009,the China Dark Matter Experiment(CDEX)collaboration was dedicated to the detection of dark matter(DM)and neutrinoless double beta decay using high-purity germanium(HPGe)detectors in the China Jinping Underground Laboratory.HPGe detectors are characterized by a high energy resolution,low analysis threshold,and low radioactive background,making them an ideal platform for the direct detection of DM.Over the years,CDEX has accumulated a massive amount of experimental data,based on which various results on DM detection and neutrinoless double beta decay have been presented.Because the dataset was collected in a low-background environment,apart from the analysis of DM-related physical channels,it has great potential as an indicator in other rare physical events searches.Furthermore,by providing raw pulse shapes,the dataset can serve as a tool for effectively understanding the internal mechanisms of HPGe detectors.
基金supported by the Innovation Program for Quantum Science and Technology(Grant No.2024ZD0302500)the National Natural Science Foundation of China(Grant No.62250710162)the Beijing Natural Science Foundation(Grant No.Z230005)。
文摘Quantum key distribution(QKD)is recognized as an unconditionally secure method of communication encryption,relying solely on the principles of quantum mechanics.A key performance metric for QKD systems is secure key rate(SKR),which is a critical factor for real-world applications.Herein,we report a practical QKD system,equipped with compact gated InGaAs/InP single-photon detectors(SPDs),that can generate a high SKR of 15.2 Mb/s with a channel loss of 2 dB.This exceptional performance stems from the ultra-low afterpulsing probability of the SPDs,which significantly reduces the bit error rate in the QKD system.The typical quantum bit error rate is 1.3%.The results validate the feasibility of an integrated,practical QKD system and offer a reliable solution for the future development of real-world QKD networks.
基金supported by the National Key Research and Development Program of China(No.2020YFE0202002)the National Natural Science Foundation of China(Nos.11875146 and U1932143)。
文摘Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in 2021.The pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μm.The array is divided into 16 subarrays,with pixels of 400 rows×32 columns per subarray.Each pixel incorporates two charge sensors:a diode sensor and a Topmetal sensor.The in-pixel circuit primarily consists of a charge-sensitive amplifier for energy measurements,a discriminator with a peak-holding circuit,and a time-to-amplitude converter for time-of-arrival measurements.The pixel of Topmetal-M2 has a charge input range of~0-3 k e-,a voltage output range of~0-180 mV,and a charge-voltage conversion gain of~59.56μV∕e-.The average equivalent noise charge of Topmetal-M2,which includes the readout electronic system noise,is~43.45 e-.In the scanning mode,the time resolution of Topmetal-M2 is 1 LSB=1.25μs,and the precision is^()7.41μs.At an operating voltage of 1.5 V,Topmetal-M2 has a power consumption of~49 mW∕cm~2.In this article,we provide a comprehensive overview of the chip architecture,pixel working principles,and functional behavior of Topmetal-M2.Furthermore,we present the results of preliminary tests conducted on Topmetal-M2,namely,alpha-particle and soft X-ray tests.
基金Supported by the National Key Research and Development Program of China(2022YFA1404602)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0580000)+3 种基金the National Natural Science Foundation of China(U23B2045,62305362)the Program of Shanghai Academic/Technology Research Leader(22XD1424400)the Fund of SITP Innovation Foundation(CX-461 and CX-522)Special Project to Seize the Commanding Heights of Science and Technology of Chinese Academy of Sciences,subtopic(GJ0090406-6).
文摘The polarization properties of light are widely applied in imaging,communications,materials analy⁃sis,and life sciences.Various methods have been developed that can measure the polarization information of a target.However,conventional polarization detection systems are often bulky and complex,limiting their poten⁃tial for broader applications.To address the challenges of miniaturization,integrated polarization detectors have been extensively explored in recent years,achieving significant advancements in performance and functionality.In this review,we focus mainly on integrated polarization detectors with innovative features,including infinitely high polarization discrimination,ultrahigh sensitivity to polarization state change,full Stokes parameters measure⁃ment,and simultaneous perception of polarization and other key properties of light.Lastly,we discuss the oppor⁃tunities and challenges for the future development of integrated polarization photodetectors.
基金supported by the Natural Science Foundation of Gansu Province(No.22JR5RA118)the National Natural Science Foundation of China(Nos.12121005 and U1932138)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB34010000)。
文摘The measurement of low-level radioactivity using high-purity germanium(HPGe)detectors is important in applications such as environmental background radiation,material screening,and rare decays.The dead layers,dead zones,aluminum shell thickness,and diameter of Ge crystals are the most influential factors affecting the performance of HPGe detectors;hence,precise modeling of the physical conditions of the detectors is highly desirable.In this study,the GEANT4 simulation framework with an optimized detector geometry adequately replicated the experimentally recorded spectrum.These detector simulations explored the idea of realizing a dead zone(an inactive volume)at the backend of an n-type coaxial Gecrystal.Using multigamma sources,the effect of true coincidence summing(TCS)on the full energy peak(FEP)efficiency calibration of an HPGe detector was investigated as a function of sample-to-detector distance.Good agreements between the simulated and experimental efficiencies as well as the simulated and analytically calculated summing coincidence correction coefficients were achieved.At a short distance between the source and detector,calculating the correction factors for a strong source posed challenges owing to significant deadtime and pile-up effects of the detection system.The described methodology can efficiently determine summing peak probabilities at short sample-to-detector distances.
基金supported by the Major Scientific and Technological Special Project of Anhui Province(202103a13010004)the Major Scientific and Technological Special Project of Hefei City(2021DX007)the Manufacturing Industry Project of Attracting Talents and Wisdom of Anhui Province(JB24179).
文摘Quantum key distribution(QKD)achieves information-theoretic security based on quantum mechanics principles,where single-photon detectors(SPDs)serve as critical components.This study focuses on the sinusoidal gated SPDs widely used in high-speed QKD systems.We investigate the mechanisms underlying the rising-edge jitter in detection signals,identifying contributions from factors such as the temporal width of injected optical pulses,avalanche generation processes,avalanche signal extraction,and pulse discrimination.To address the issue of excessive jitter-induced bit errors,we propose a retiming scheme that utilizes coincidence signals synchronized with the sinusoidal gating signal.This approach effectively suppresses detection signal jitter and reduces the after-pulse probability of the detector.Experimental validation using a high-precision time-to-digital converter(TDC)demonstrates a significant reduction in the rising-edge jitter distribution after applying the suppression scheme.The proposed method features clear principles and straightforward engineering implementation,avoiding direct interference with the detector’s operational processes.The designed high-speed sinusoidal gated InGaAs/InP SPD operates at 1.25 GHz,achieving a remarkable reduction in after-pulse probability from 10.7%(without jitter suppression)to 0.72%,thereby enhancing the overall performance of QKD systems.
基金the Industry-University Cooperation Project in Fujian Province University(No.2022H6020)。
文摘Self-powered neutron detectors(SPNDs)play a critical role in monitoring the safety margins and overall health of reactors,directly affecting safe operation within the reactor.In this work,a novel fault identification method based on graph convolutional networks(GCN)and Stacking ensemble learning is proposed for SPNDs.The GCN is employed to extract the spatial neighborhood information of SPNDs at different positions,and residuals are obtained by nonlinear fitting of SPND signals.In order to completely extract the time-varying features from residual sequences,the Stacking fusion model,integrated with various algorithms,is developed and enables the identification of five conditions for SPNDs:normal,drift,bias,precision degradation,and complete failure.The results demonstrate that the integration of diverse base-learners in the GCN-Stacking model exhibits advantages over a single model as well as enhances the stability and reliability in fault identification.Additionally,the GCN-Stacking model maintains higher accuracy in identifying faults at different reactor power levels.
文摘SiGe offers a low-cost alternative to conventional infrared sensor material systems such as InGaAs, InSb, and HgCdTe for developing near-infrared (NIR) photodetector devices that do not require cooling and can operate with relatively low dark current. As a result of the significant difference in thermal expansion coefficients between germanium (Ge) and silicon (Si), tensile strain incorporated into SiGe detector devices through specialized growth processes can extend their NIR wavelength range of operation. We have utilized high throughput, large-area complementary metal-oxide semiconductor (CMOS) technology to fabricate Ge based p-i-n (PIN) detector devices on 300 mm Si wafers. The two-step device fabrication process, designed to effectively reduce the density of defects and dislocations arising during deposition that form recombination centers which can result in higher dark current, involves low temperature epitaxial deposition of Ge to form a thin p<sup>+</sup> seed layer, followed by higher temperature deposition of a thicker Ge intrinsic layer. Phosphorus was then ion-implanted to create devices with n<sup>+</sup> regions of various doping concentrations. Secondary ion mass spectroscopy (SIMS) has been utilized to determine the doping profiles and material compositions of the layers. In addition, electrical characterization of the I-V photoresponse of different devices from the same wafer with various n<sup>+</sup> region doping concentrations has demonstrated low dark current levels (down to below 1 nA at -1 V bias) and comparatively high photocurrent at reverse biases, with optimal response for doping concentration of 5 × 10<sup>19</sup> cm<sup>-3</sup>.
基金supported in part by a grant from the University of Oklahoma Charles and Peggy Stephenson Cancer Center funded by the Oklahoma Tobacco Settlement Endowment Trust
文摘Photon counting detectors(PCDs) have attained w ide use in X-ray imaging for various preclinical and clinical applications in the past decade. This paper briefly review s the preclinical and clinical applications of PCDs based X-ray imaging systems.Starting with an introduction of X-ray single photon detection mechanism,the brief review first describes tw o major advantages of utilizing PCDs: photon energy resolving capability and electronic noise elimination. Compared to energy integrating detectors(EIDs),the aforementioned advantages make PCDs more favorable in X-ray imaging with profound benefits such as enhanced tissue contrast,decreased image noise,increased signal to noise ratio,decreased radiation dose to the small animals and patients,and more accurate material decomposition. The utilizations of PCDs in X-ray projection radiography and computed tomography(CT)including micro-CT,dedicated breast CT,K-edge CT,and clinical CT are then review ed for the imaging applications ranging from phantoms to small animals and humans. In addition,optimization methods aiming to improve the imaging performance using PCDs are briefly review ed. PCDs are not flaw less though,and their limitations are also discussed in this review. Nevertheless,PCDs may continuously contribute to the advancement of X-ray imaging techniques in future preclinical and clinical applications.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0400904)the National Natural Science Foundation for Distinguished Young Scholars,China(Grant No.61725403)+5 种基金the National Natural Science Foundation of China(Grant Nos.61574142,61322406,61704171,and 11705206)the Key Program of International Partnership Program of the Chinese Academy of Sciences(Grant No.181722KYSB20160015)the Special Project for Inter-government Collaboration of State Key Research and Development Program,China(Grant No.2016YFE0118400)the Science and Technology Service Network Initiative of the Chinese Academy of Sciences,the Jilin Provincial Science&Technology Department,China(Grant No.20180201026GX)the Interdisciplinary Innovation Team of the Chinese Academy of Sciencesthe Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2015171)
文摘Ultraviolet(UV) photodetectors based on wide band gap semiconductor have attracted much attention for their small volume, low working voltage, long lifetime, good chemical and thermal stability. Up to now, many researches have been done on the semiconductors based UV detectors and some kinds of detectors have been made, such as metal–semiconductor–metal(MSM), Schottky, and PIN-type detectors. However, the sensitivity values of those detectors are still far from the expectation. Recent years, surface plasmon(SP) has been considered to be an effective way to enhance the sensitivity of semiconductor based UV photodetector. When the light is matched with the resonance frequency of surface plasmon, the localized field enhancement or scattering effect will happen and thus the spectral response will be enhanced.Here, we present an overview of surface plasmon enhancing the performance of UV detectors, including the GaN, ZnO,and other wide band gap semiconductor UV detectors. Both fundamental and experimental achievements are contained in this review.
基金supported by a Grant from the Ministry of Science and Technology of China(No.2016YFA0400301)。
文摘The charge readout of a liquid xenon(LXe)detector via proportional scintillation in the liquid phase was first realized by the Waseda group 40 years ago,but the technical challenges involved were overwhelming.Although the tests were successful,this method was finally discarded and eventually nearly forgotten.Currently,this approach is not considered for large LXe dark matter detectors.Instead,the dual-phase technology was selected despite many limitations and challenges.In two independent studies,two groups from Columbia University and Shanghai Jiao Tong University reevaluated proportional scintillation in the liquid phase.Both studies established the merits for very large LXe detectors,but the Columbia group also encountered apparent limitations,namely the shadowing of the light by the anode wires,and a dependence of the pulse shape on the drift path of the electrons in the anode region.The differences between the two studies,however,are not intrinsic to the technique,but a direct consequence of the chosen geometry.Taking the geometrical differences into account,the results match without ambiguity.They also agree with the original results from the Waseda group.
基金This work was supported by the National Key Research and Development Project(No.2016YFA0400502)the National Natural Science Foundation of China(No.11775312).
文摘It is of particular interest to investigate nuclear fusion reactions generated by high-intensity lasers in plasma environments that are similar to real astrophysical conditions.We have experimentally investigated2H(d,p)3H,one of the most crucial reactions in big bang nucleosynthesis models,at the Shenguang-Ⅱlaser facility.In this work,we present a new calibration of CR-39 solidstate track detectors,which are widely employed as the main diagnostics in this type of fusion reaction experiment.We measure the dependence of the track diameter on the proton energy.It is found that the track diameters of protons with different energies are likely to be identical.We propose that in this case,the energy of the reaction products can be obtained by considering both the diameters and gray levels of these tracks.The present results would be very helpful for analyzing the2 H(d,p)3H reaction products recorded with the same batch of CR-39 solid-state track detectors.
文摘In the present work, we designed the new type of photonic crystals (PCs) as reflectors. Reflections from single layer of Al2O3/MgO PC help us in recapturing the light that does escape from the scintillation surface. Photonic crystals in one dimension array of Al2O3 and MgO with silver at periodicities N = 1, 2 and 3 were used as a reflector around the surface of the scintillation volume. Scintillation detectors are widely used in nuclear medicine. The efficiency is an important parameter for characterizing the capability of the detectors. The counting efficiency of the detectors depends on the light emission induced by radiation. The light then was converted by the photomultiplier tube into electrical pulses. The efficiency may increase by an amount of 1.64% if MgO-Ag photonic crystals are used at periodicity N = 1 as a reflector.
文摘Several Constant False Alarm Rate （CFAR） architectures, where radar systems often employ them to automatically adapt the detection threshold to the local background noise or clutter power in an attempt to maintain an approximately constant rate of false alarm, have been recently proposed to estimate the unknown noise power level. Since the Ordered-Statistics （OS） based algorithm has some advantages over the Cell-Averaging （CA） technique, we are concerned here with this type of CFAR detectors. The Linearly Combined Ordered-Statistic （LCOS） processor, which sets threshold by processing a weighted ordered range samples within finite moving window, may actually perform somewhat better than the conventional OS detector. Our objective in this paper is to analyze the LCOS processor along with the conventional OS scheme for the case where the radar receiver incorporates a postdetection integrator amongst its contents and where the operating environments contain a number of secondary interfering targets along with the primary target of concern and the two target types fluctuate in accordance with the Swerling Ⅱ fluctuation model and to compare their performances under various operating conditions.
基金supported by the project“PARIDE”(Perovskite Advanced Radiotherapy&Imaging Detectors),funded under the Regional Research and Innovation Programme POR-FESR Lazio 2014-2020(project number:A0375-2020-36698).
文摘Metal-halide perovskites are revolutionizing the world of X-ray detectors,due to the development of sensitive,fast,and cost-effective devices.Self-powered operation,ensuring portability and low power consumption,has also been recently demonstrated in both bulk materials and thin films.However,the signal stability and repeatability under continuous X-ray exposure has only been tested up to a few hours,often reporting degradation of the detection performance.Here it is shown that self-powered direct X-ray detectors,fabricated starting from a FAPbBr_(3)submicrometer-thick film deposition onto a mesoporous TiO_(2)scaffold,can withstand a 26-day uninterrupted X-ray exposure with negligible signal loss,demonstrating ultra-high operational stability and excellent repeatability.No structural modification is observed after irradiation with a total ionizing dose of almost 200 Gy,revealing an unexpectedly high radiation hardness for a metal-halide perovskite thin film.In addition,trap-assisted photoconductive gain enabled the device to achieve a record bulk sensitivity of 7.28 C Gy^(−1)cm^(−3)at 0 V,an unprecedented value in the field of thin-film-based photoconductors and photodiodes for“hard”X-rays.Finally,prototypal validation under the X-ray beam produced by a medical linear accelerator for cancer treatment is also introduced.
基金the National Natural Science Foundation of China(Grant Nos.11933006,61805060,and 61290304).
文摘A type of Si-based blocked impurity band photoelectric detector with a planar architecture is designed and demonstrated by a modified silicon semiconductor processing technique.In this route,multiple ion implantation is utilized to ensure the uniform distribution of the P elements in silicon,and rapid thermal annealing treatment is used to activate the P atoms and reduce damages caused by ion-implantation.The fabricated prototype device exhibits an excellent photoelectric response performance.With a direct current(DC)bias voltage of-2.3 V,the device detectivity to blackbody irradiation is as high as 5×10^(13)cm·Hz^(1/2)/W,which corresponds to a device responsivity of nearly 4.6 A/W,showing their potential applications in infrared detection,infrared astrophysics,and extraterrestrial life science.In particular,the developed device preparation process is compatible with that for the CMOS-circuit,which greatly reduces the manufacturing cost.
基金supported by FAPESP (under grant No.1998/13468-9 and2006/56041-3)CNPq (under grant No. 306467/03-8), CAPES and MCT/INPE
文摘Resonant-mass gravitational wave detectors are reviewed from the concept of gravitational waves and its mathematical derivation, using Einstein＇s general relativity, to the present status of bars and spherical detectors, and their prospects for the future, which include dual detectors and spheres with non-resonant transducers. The review not only covers technical aspects of detectors and sciences that will be done, but also analyzes the subject in a historical perspective, covering the various detection efforts over four decades, starting from Weber＇s pioneering work.
基金Research of the photoelectric properties of theκ(ε)-Ga_(2)O_(3)films was supported by the Russian Science Foundation,grant number 20-79-10043-P.Fabrication of the ultraviolet detectors based on theκ(ε)-Ga_(2)O_(3)layers was supported by the grant under the Decree of the Government of the Rus-sian Federation No.220 of 09 April 2010(Agreement No.075-15-2022-1132 of 01 July 2022)Research of the structural prop-erties of theκ(ε)-Ga_(2)O_(3)was supported by the St.Petersburg State University,grant number 94034685.
文摘High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.
