This paper proposes two optimal designs of single photon avalanche diodes(SPADs) minimizing dark count rate(DCR). The first structure is introduced as p^+/pwell/nwell, in which a specific shallow pwell layer is added ...This paper proposes two optimal designs of single photon avalanche diodes(SPADs) minimizing dark count rate(DCR). The first structure is introduced as p^+/pwell/nwell, in which a specific shallow pwell layer is added between p^+and nwell layers to decrease the electric field below a certain threshold. The simulation results show on average 19.7%and 8.5% reduction of p^+/nwell structure’s DCR comparing with similar previous structures in different operational excess bias and temperatures respectively. Moreover, a new structure is introduced as n+/nwell/pwell, in which a specific shallow nwell layer is added between n+and pwell layers to lower the electric field below a certain threshold. The simulation results show on average 29.2% and 5.5% decrement of p^+/nwell structure’s DCR comparing with similar previous structures in different operational excess bias and temperatures respectively. It is shown that in higher excess biases(about 6 volts), the n+/nwell/pwell structure is proper to be integrated as digital silicon photomultiplier(dSiPM) due to low DCR. On the other hand, the p^+/pwell/nwell structure is appropriate to be utilized in dSiPM in high temperatures(above 50?C) due to lower DCR value.展开更多
In this research, the excellent parameter for regular Quality Control (QC) testing of intrinsic uniformity for dual-head Single Photon Emission Computed Tomography (SPECT) gamma camera is determined. The integral and ...In this research, the excellent parameter for regular Quality Control (QC) testing of intrinsic uniformity for dual-head Single Photon Emission Computed Tomography (SPECT) gamma camera is determined. The integral and differential intrinsic uniformity tests for both Useful Field Of View (UFOV) and Centre Field Of View (CFOV) were done by insertion a point-source of 99mTc in front of the detectors with detached collimators to measure the effect of source to camera distance and a count rate on intrinsic uniformity. The result reveals that the best intrinsic uniformity image is obtained at source-to-camera distance of 3 m and a count rate between 16 and 60 M.展开更多
A high-sensitivity,low-noise single photon avalanche diode(SPAD)detector was presented based on a 180 nm BCD process.The proposed device utilizes a p-implant layer/high-voltage n-well(HVNW)junction to form a deep aval...A high-sensitivity,low-noise single photon avalanche diode(SPAD)detector was presented based on a 180 nm BCD process.The proposed device utilizes a p-implant layer/high-voltage n-well(HVNW)junction to form a deep avalanche multiplication region for near-infrared(NIR)sensitivity enhancement.By optimizing the device size and electric field of the guard ring,the fill factor(FF)is significantly improved,further increasing photon detection efficiency(PDE).To solve the dark noise caused by the increasing active diameter,a field polysilicon gate structure connected to the p+anode was investigated,effectively suppressing dark count noise by 76.6%.It is experimentally shown that when the active diameter increases from 5 to 10μm,the FF is significantly improved from 20.7%to 39.1%,and thus the peak PDE also rises from 13.3%to 25.8%.At an excess bias voltage of 5 V,a NIR photon detection probability(PDP)of 6.8%at 905 nm,a dark count rate(DCR)of 2.12 cps/μm^(2),an afterpulsing probability(AP)of 1.2%,and a timing jitter of 216 ps are achieved,demonstrating excellent single photon detection performance.展开更多
In this work,we achieve high count-rate single-photon output in single-mode(SM)optical fiber.Epitaxial and dilute InAs/GaAs quantum dots(QDs)are embedded in a GaAs/AlGaAs distributed Bragg reflector(DBR)with a micro-p...In this work,we achieve high count-rate single-photon output in single-mode(SM)optical fiber.Epitaxial and dilute InAs/GaAs quantum dots(QDs)are embedded in a GaAs/AlGaAs distributed Bragg reflector(DBR)with a micro-pillar cavity,so as to improve their light emission extraction in the vertical direction,thereby enhancing the optical SM fiber’s collection capabil-ity(numerical aperture:0.13).By tuning the temperature precisely to make the quantum dot exciton emission resonant to the micro-pillar cavity mode(Q~1800),we achieve a fiber-output single-photon count rate as high as 4.73×10^(6) counts per second,with the second-order auto-correlation g2(0)remaining at 0.08.展开更多
This study presents a low-noise,high-rate front-end readout application-specific integrated circuit(ASIC)designed for the electromagnetic calorimeter(ECAL)of the Super Tau-Charm Facility(STCF).To address the high back...This study presents a low-noise,high-rate front-end readout application-specific integrated circuit(ASIC)designed for the electromagnetic calorimeter(ECAL)of the Super Tau-Charm Facility(STCF).To address the high background-count rate in the STCF ECAL,the temporal features of signals are analyzed node-by-node along the chain of the analog front-end circuit.Then,the system is optimized to mitigate the pile-up effects and elevate the count rate to megahertz levels.First,a charge-sensitive amplifier(CSA)with a fast reset path is developed,enabling quick resetting when the output reaches the maximum amplitude.This prevents the CSA from entering a pulse-dead zone owing to amplifier saturation caused by the pile-up.Second,a high-order shaper with baseline holder circuits is improved to enhance the anti-pile-up capability while maintaining an effective noise-filtering performance.Third,a high-speed peak-detection and hold circuit with an asynchronous first-input-first-output buffer function is proposed to hold and read the piled-up signals of the shaper.The ASIC is designed and manufactured using a standard commercial 1P6M 0.18μm mixed-signal CMOS process with a chip area of 2.4 mm×1.6 mm.The measurement results demonstrate a dynamic range of 4–500 fC with a nonlinearity error below 1.5%.For periodically distributed input signals,a count rate of 1.5 MHz/Ch is achieved with a peak time of 360 ns,resulting in an equivalent noise charge(ENC)of 2500 e^(-)-.The maximum count rate is 4 MHz/Ch at a peak time of 120 ns.At a peak time of 1.68μs with a 270 pF external capacitance,the minimum ENC is 1966 e^(-)-,and the noise slope is 3.08 e^(-)-∕pF.The timing resolution is better than 125 ps at an input charge of 200 fC.The power consumption is 35 mW/Ch.展开更多
Top Japanese sprinters were evaluated for their physical condition, autonomic function, blood chemistry, differential leukocyte count and blood lactate level before and after short, maximal exercise to explore methods...Top Japanese sprinters were evaluated for their physical condition, autonomic function, blood chemistry, differential leukocyte count and blood lactate level before and after short, maximal exercise to explore methods of quantifying their conditioning level. Statistical analysis of data obtained before and 10 min after exercise were used to estimate the athletes’ autonomic capacity during recovery. Pre and post exercise variances in differential leukocyte count revealed strong correlations between neutrophil and sympathetic activity, and lymphocyte and parasympathetic activity. The results of the study demonstrated significant alterations in autonomic parameters and differential white blood cell count in response to maximal exercise.展开更多
Hamamatsu R1924A is one of the most widely used photomultiplier tubes(PMTs) in nuclear physics.Since the active base suitable for R1924A is still not available in market, an active base is designed for Hamamatsu R1924...Hamamatsu R1924A is one of the most widely used photomultiplier tubes(PMTs) in nuclear physics.Since the active base suitable for R1924A is still not available in market, an active base is designed for Hamamatsu R1924A PMT, and the test results at high counting rates are presented. The active bases with two different sets of resistor chains were tested and compared by a frequency-controlled green straw hat LED light. A stable signal output up to 100 kHz is achieved using frequency-controlled LED pulsed light. The temperature of bases, which reflects the power consumption and is crucial for applications in vacuum, is also monitored with the same LED pulsed light. The temperature of the active base with smaller resistances reaches about twice of that of the active base with larger resistances in the resistor chain. For the applications in vacuum, the active base with resistance between the two sets of resistor chains may be preferable.展开更多
This paper introduces the test results of the soil magnetic survey and the integrated gamma-ray TLD and TC methods for sandstone-type uranium exploration and describes the prospecting mechanism. The tests have proved ...This paper introduces the test results of the soil magnetic survey and the integrated gamma-ray TLD and TC methods for sandstone-type uranium exploration and describes the prospecting mechanism. The tests have proved that these approaches have yielded good results on classifying the sedimentary facies, defining the redox transitional zones and reflecting deep mineralization information. They may probably become new methods on searching for sandstone-type uranium deposits.展开更多
The aim of this study was to evaluate the impact of the somatic cell count (SCC) levels measured at 28-test-day intervals or pregnancy rate at the first artificial insemination of Holstein Friesian cows. All necessary...The aim of this study was to evaluate the impact of the somatic cell count (SCC) levels measured at 28-test-day intervals or pregnancy rate at the first artificial insemination of Holstein Friesian cows. All necessary information was taken from test day and farm records. Levels of SCC in milk, 30 days before, and 30 days after the first artificial insemination (FAI) date were divided into 4 categories and their interconnection with pregnancy rate (PR) at FAI was evaluated by applying logistic models. A SCC threshold of 150.000 cells/ml of milk was used to differentiate uninfected udders and infected udders of Holstein Friesian cows. A level of SCC > 150.000 cells/ml in milk, and a level of SCC < 150.000 cells/ml before and after FAI respectively were considered udders with new infections. A level of SCC > 150.000 cells/ml in milk before FAI as well as after FAI, was considered chronically infected udders or subclinical intramammary infections (IMI). Data from 792 FAIs from farm and test day records over a 4-year period (2019-2022) were evaluated. The outcome of this study revealed that the risk for low PR at the first AI was increased in cows with infected udders (OR = 1.33, CI 0.99 - 1.78), compared with uninfected udders. Increased levels of SCC after FAI had a negative effect on PR, while before FAI was not affected. To achieve a good PR, mastitis control measures must be fully adopted to a large extent around the first AI.展开更多
Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.Howe...Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.However,with the rapid development of remote imaging,sensing technologies,and long-range quantum communication with fewer topographical constraints,the demand for high-efficiency single-photon detectors integrated with avionic platforms is rapidly growing.We herein designed and manufactured the first drone-based SNSPD system with a system detection efficiency(SDE)as high as 91.8%.This drone-based system incorporates high-performance NbTiN SNSPDs,a self-developed miniature liquid helium dewar,and custom-built integrated electrical setups,making it capable of being launched in complex topographical conditions.Such a drone-based SNSPD system may open the use of SNSPDs for applications that demand high SDE in complex environments.展开更多
A near-infrared(NIR) enhanced silicon single-photon avalanche diode(SPAD) detector is proposed using 0.18 μm bipolar-CMOS-DMOS technology. It is based on a deep multiplication region, formed by a junction between the...A near-infrared(NIR) enhanced silicon single-photon avalanche diode(SPAD) detector is proposed using 0.18 μm bipolar-CMOS-DMOS technology. It is based on a deep multiplication region, formed by a junction between the highvoltage P-well(HVPW) and high-voltage buried N+ layer, to enhance the NIR photon detection probability(PDP). Thanks to the lightly doped P-type epitaxial layer, the electric field in the guard ring is reduced and premature breakdown is prevented. In particular, an extra P-type implantation layer(PIL) is added to the HVPW to reduce the breakdown voltage and enhance the device's sensitivity. Further research on the impact of different PIL sizes on the device performance is carried out. It is experimentally shown that at an excess bias voltage of 5 V, the optimized SPAD achieves a dark count rate of 0.64 cps/μm^(2), peak PDP of 54.8% at 555 nm and PDP of 10.53% at 905 nm. The full width at half-maximum of the timing jitter is 285 ps, and the afterpulsing probability is lower than 1.17%. This novel device provides a practical, low-cost solution for high-performance NIR time-of-flight detectors and 3D imaging sensors.展开更多
文摘This paper proposes two optimal designs of single photon avalanche diodes(SPADs) minimizing dark count rate(DCR). The first structure is introduced as p^+/pwell/nwell, in which a specific shallow pwell layer is added between p^+and nwell layers to decrease the electric field below a certain threshold. The simulation results show on average 19.7%and 8.5% reduction of p^+/nwell structure’s DCR comparing with similar previous structures in different operational excess bias and temperatures respectively. Moreover, a new structure is introduced as n+/nwell/pwell, in which a specific shallow nwell layer is added between n+and pwell layers to lower the electric field below a certain threshold. The simulation results show on average 29.2% and 5.5% decrement of p^+/nwell structure’s DCR comparing with similar previous structures in different operational excess bias and temperatures respectively. It is shown that in higher excess biases(about 6 volts), the n+/nwell/pwell structure is proper to be integrated as digital silicon photomultiplier(dSiPM) due to low DCR. On the other hand, the p^+/pwell/nwell structure is appropriate to be utilized in dSiPM in high temperatures(above 50?C) due to lower DCR value.
文摘In this research, the excellent parameter for regular Quality Control (QC) testing of intrinsic uniformity for dual-head Single Photon Emission Computed Tomography (SPECT) gamma camera is determined. The integral and differential intrinsic uniformity tests for both Useful Field Of View (UFOV) and Centre Field Of View (CFOV) were done by insertion a point-source of 99mTc in front of the detectors with detached collimators to measure the effect of source to camera distance and a count rate on intrinsic uniformity. The result reveals that the best intrinsic uniformity image is obtained at source-to-camera distance of 3 m and a count rate between 16 and 60 M.
基金supported by the National Natural Science Foundation of China under Grant 62171233the Natural Science Foundation of China,Jiangsu Province under Grant BK20241891the Jiangsu Province Graduate Research and Practice Innovation Plan under Grants SJCX24_0313 and KYCX24_1169。
文摘A high-sensitivity,low-noise single photon avalanche diode(SPAD)detector was presented based on a 180 nm BCD process.The proposed device utilizes a p-implant layer/high-voltage n-well(HVNW)junction to form a deep avalanche multiplication region for near-infrared(NIR)sensitivity enhancement.By optimizing the device size and electric field of the guard ring,the fill factor(FF)is significantly improved,further increasing photon detection efficiency(PDE).To solve the dark noise caused by the increasing active diameter,a field polysilicon gate structure connected to the p+anode was investigated,effectively suppressing dark count noise by 76.6%.It is experimentally shown that when the active diameter increases from 5 to 10μm,the FF is significantly improved from 20.7%to 39.1%,and thus the peak PDE also rises from 13.3%to 25.8%.At an excess bias voltage of 5 V,a NIR photon detection probability(PDP)of 6.8%at 905 nm,a dark count rate(DCR)of 2.12 cps/μm^(2),an afterpulsing probability(AP)of 1.2%,and a timing jitter of 216 ps are achieved,demonstrating excellent single photon detection performance.
基金supported by the Key-Area Research and Development Program of Guangdong Province(Grant No.2018B030329001)the National Key Technologies R&D Program of China(2018YFA0306101)+2 种基金The Scientific Instrument Developing Project of the Chinese Academy of Science(YJKYYQ20170032)the National Natural Science Foundation of China(61505196)the Program of Beijing Academy of Quantum Information Sciences(Grant No.Y18G01).
文摘In this work,we achieve high count-rate single-photon output in single-mode(SM)optical fiber.Epitaxial and dilute InAs/GaAs quantum dots(QDs)are embedded in a GaAs/AlGaAs distributed Bragg reflector(DBR)with a micro-pillar cavity,so as to improve their light emission extraction in the vertical direction,thereby enhancing the optical SM fiber’s collection capabil-ity(numerical aperture:0.13).By tuning the temperature precisely to make the quantum dot exciton emission resonant to the micro-pillar cavity mode(Q~1800),we achieve a fiber-output single-photon count rate as high as 4.73×10^(6) counts per second,with the second-order auto-correlation g2(0)remaining at 0.08.
基金supported by the National Natural Science Foundation of China(Nos.12375191,12275218,12341502,12105224,12205307)National Key Research and Development Program of China(No.2023YFE0206300,2023YFF0719600)+2 种基金Guangdong Basic and Applied Basic Research Foundation(No.2024A1515012141)China Postdoctoral Science Foundation(No.2023M742850)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(No.CX2021025)。
文摘This study presents a low-noise,high-rate front-end readout application-specific integrated circuit(ASIC)designed for the electromagnetic calorimeter(ECAL)of the Super Tau-Charm Facility(STCF).To address the high background-count rate in the STCF ECAL,the temporal features of signals are analyzed node-by-node along the chain of the analog front-end circuit.Then,the system is optimized to mitigate the pile-up effects and elevate the count rate to megahertz levels.First,a charge-sensitive amplifier(CSA)with a fast reset path is developed,enabling quick resetting when the output reaches the maximum amplitude.This prevents the CSA from entering a pulse-dead zone owing to amplifier saturation caused by the pile-up.Second,a high-order shaper with baseline holder circuits is improved to enhance the anti-pile-up capability while maintaining an effective noise-filtering performance.Third,a high-speed peak-detection and hold circuit with an asynchronous first-input-first-output buffer function is proposed to hold and read the piled-up signals of the shaper.The ASIC is designed and manufactured using a standard commercial 1P6M 0.18μm mixed-signal CMOS process with a chip area of 2.4 mm×1.6 mm.The measurement results demonstrate a dynamic range of 4–500 fC with a nonlinearity error below 1.5%.For periodically distributed input signals,a count rate of 1.5 MHz/Ch is achieved with a peak time of 360 ns,resulting in an equivalent noise charge(ENC)of 2500 e^(-)-.The maximum count rate is 4 MHz/Ch at a peak time of 120 ns.At a peak time of 1.68μs with a 270 pF external capacitance,the minimum ENC is 1966 e^(-)-,and the noise slope is 3.08 e^(-)-∕pF.The timing resolution is better than 125 ps at an input charge of 200 fC.The power consumption is 35 mW/Ch.
文摘Top Japanese sprinters were evaluated for their physical condition, autonomic function, blood chemistry, differential leukocyte count and blood lactate level before and after short, maximal exercise to explore methods of quantifying their conditioning level. Statistical analysis of data obtained before and 10 min after exercise were used to estimate the athletes’ autonomic capacity during recovery. Pre and post exercise variances in differential leukocyte count revealed strong correlations between neutrophil and sympathetic activity, and lymphocyte and parasympathetic activity. The results of the study demonstrated significant alterations in autonomic parameters and differential white blood cell count in response to maximal exercise.
基金supported by the National Natural Science Foundation of China(Nos.91426301 and 11075189)the Strategic Priority Research Program of the Chinese Academy of Sciences"ADS project"(No.XDA03030200)+2 种基金the Program for the CAS"Light of West China"(No.29Y601030)the US Department of Energy(No.DE-FG02-93ER40773)the program of the"visiting professorship of senior international scientists of the Chinese Academy of Sciences"for their support during his stay at the IMP
文摘Hamamatsu R1924A is one of the most widely used photomultiplier tubes(PMTs) in nuclear physics.Since the active base suitable for R1924A is still not available in market, an active base is designed for Hamamatsu R1924A PMT, and the test results at high counting rates are presented. The active bases with two different sets of resistor chains were tested and compared by a frequency-controlled green straw hat LED light. A stable signal output up to 100 kHz is achieved using frequency-controlled LED pulsed light. The temperature of bases, which reflects the power consumption and is crucial for applications in vacuum, is also monitored with the same LED pulsed light. The temperature of the active base with smaller resistances reaches about twice of that of the active base with larger resistances in the resistor chain. For the applications in vacuum, the active base with resistance between the two sets of resistor chains may be preferable.
文摘This paper introduces the test results of the soil magnetic survey and the integrated gamma-ray TLD and TC methods for sandstone-type uranium exploration and describes the prospecting mechanism. The tests have proved that these approaches have yielded good results on classifying the sedimentary facies, defining the redox transitional zones and reflecting deep mineralization information. They may probably become new methods on searching for sandstone-type uranium deposits.
文摘The aim of this study was to evaluate the impact of the somatic cell count (SCC) levels measured at 28-test-day intervals or pregnancy rate at the first artificial insemination of Holstein Friesian cows. All necessary information was taken from test day and farm records. Levels of SCC in milk, 30 days before, and 30 days after the first artificial insemination (FAI) date were divided into 4 categories and their interconnection with pregnancy rate (PR) at FAI was evaluated by applying logistic models. A SCC threshold of 150.000 cells/ml of milk was used to differentiate uninfected udders and infected udders of Holstein Friesian cows. A level of SCC > 150.000 cells/ml in milk, and a level of SCC < 150.000 cells/ml before and after FAI respectively were considered udders with new infections. A level of SCC > 150.000 cells/ml in milk before FAI as well as after FAI, was considered chronically infected udders or subclinical intramammary infections (IMI). Data from 792 FAIs from farm and test day records over a 4-year period (2019-2022) were evaluated. The outcome of this study revealed that the risk for low PR at the first AI was increased in cows with infected udders (OR = 1.33, CI 0.99 - 1.78), compared with uninfected udders. Increased levels of SCC after FAI had a negative effect on PR, while before FAI was not affected. To achieve a good PR, mastitis control measures must be fully adopted to a large extent around the first AI.
基金the Innovation Program for Quantum Science and Technology(Grant No.2023ZD0300100)the National Key Research and Development Program of China(Grant Nos.2023YFB3809600 and 2023YFC3007801)+1 种基金the National Natural Science Foundation of China(Grant Nos.62301543 and U24A20320)the Shanghai Sailing Program(Grant No.21YF1455700).
文摘Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.However,with the rapid development of remote imaging,sensing technologies,and long-range quantum communication with fewer topographical constraints,the demand for high-efficiency single-photon detectors integrated with avionic platforms is rapidly growing.We herein designed and manufactured the first drone-based SNSPD system with a system detection efficiency(SDE)as high as 91.8%.This drone-based system incorporates high-performance NbTiN SNSPDs,a self-developed miniature liquid helium dewar,and custom-built integrated electrical setups,making it capable of being launched in complex topographical conditions.Such a drone-based SNSPD system may open the use of SNSPDs for applications that demand high SDE in complex environments.
基金Project supported by the National Natural Science Foundation of China (Grant No. 62171233)the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20241891)the Jiangsu Province Postgraduate Innovation Program (Grant No. KYCX23_0999)。
文摘A near-infrared(NIR) enhanced silicon single-photon avalanche diode(SPAD) detector is proposed using 0.18 μm bipolar-CMOS-DMOS technology. It is based on a deep multiplication region, formed by a junction between the highvoltage P-well(HVPW) and high-voltage buried N+ layer, to enhance the NIR photon detection probability(PDP). Thanks to the lightly doped P-type epitaxial layer, the electric field in the guard ring is reduced and premature breakdown is prevented. In particular, an extra P-type implantation layer(PIL) is added to the HVPW to reduce the breakdown voltage and enhance the device's sensitivity. Further research on the impact of different PIL sizes on the device performance is carried out. It is experimentally shown that at an excess bias voltage of 5 V, the optimized SPAD achieves a dark count rate of 0.64 cps/μm^(2), peak PDP of 54.8% at 555 nm and PDP of 10.53% at 905 nm. The full width at half-maximum of the timing jitter is 285 ps, and the afterpulsing probability is lower than 1.17%. This novel device provides a practical, low-cost solution for high-performance NIR time-of-flight detectors and 3D imaging sensors.
