The rapid growth of neutron flux has driven the development of^(3)He-free neutron detectors to satisfy the requirements of the neutron scattering instruments under construction or planned at the China Spallation Neutr...The rapid growth of neutron flux has driven the development of^(3)He-free neutron detectors to satisfy the requirements of the neutron scattering instruments under construction or planned at the China Spallation Neutron Source(CSNS).Position-sensitive neutron detectors with a high counting rate and large area play an important role in the instruments performing neutron measurements in or close to the direct beam.The ceramic gas-electron-multiplier(GEM)detector serves as a promising solution,and considerable work has been done using the small-area GEM neutron detectors.In this article,we designed and constructed a detector prototype utilizing ceramic GEM foils with an effective area of about307 mm×307 mm.To evaluate and investigate their basic characteristics,the Monte Carlo(MC)tool FLUKA was employed and several neutron beam tests were conducted at CSNS.The simulated spatial resolution was basically in agreement with the measured value of 2.50±0.01 mm(FWHM).The wavelength spectra measurement was verified through comparisons with a commercial beam monitor.In addition,a detection efficiency of 4.7±0.1%was achieved for monoenergetic neutrons of 1.59 A wavelength.This is consistent with the simulated result.The results indicate that the large-area ceramic GEM detector is a good candidate to implement neutron beam measurements.Its efficiency can be improved in a cascading manner to approach that reached by traditional^(3)He detectors.展开更多
The requirement of a large number of electronic channels poses a big challenge to the further applications of Micro-pattern Gas Detectors （MPGDs）. By using the redundancy that at least two neighboring strips record ...The requirement of a large number of electronic channels poses a big challenge to the further applications of Micro-pattern Gas Detectors （MPGDs）. By using the redundancy that at least two neighboring strips record the signal of a particle, a novel method of encoded multiplexing readout for MPGDs is presented in this paper. The method offers a feasible and easily-extensible way of encoding and decoding, and can significantly reduce the number of readout channels. A verification test was carried out on a 5 cm×5 cm Thick Gas Electron Multiplier （THGEM） detector using a 8 keV Cu X-ray source with 100um slit, where 166 strips were read out by 21 encoded readout channels. The test results show good linearity in its position response, and the spatial resolution root-mean-square （RMS） of the test system is about 260um. This method has potential to build large area detectors and can be easily adapted to other detectors similar to MPGDs.展开更多
A scalable readout system （SRS） is designed to provide a general solution for different micro-pattern gas detectors in various applications. The system mainly consists of three kinds of modules： the ASIC card, the ...A scalable readout system （SRS） is designed to provide a general solution for different micro-pattern gas detectors in various applications. The system mainly consists of three kinds of modules： the ASIC card, the adapter card and the front-end card （FEC）. The ASIC cards, mounted with particular ASIC chips, are designed for receiving detector signals. The adapter card is in charge of digitizing the output signals from several ASIC cards. The FEC, edged-mounted with the adapter, has field-programmable gate array （FPGA）-based reconfigurable logic and I/O interfaces, allowing users to choose different ASIC cards and adapters for different experiments, which expands the system to various applications. The FEC transfers data through Gigabit Ethernet protocol realized by a TCP processor （SiTCP） IP core in FPGA. By assembling a flexible number of FECs in parallel through Gigabit Ethernet, the readout system can be tailored to specific sizes to adapt to the experiment scales and readout requirements. In this paper, two kinds of multi-channel ASIC chip, VA140 and AGET, are applied to verify the scalability of this SRS architecture. Based on this VA140 or AGET SRS, one FEC covers 8 ASIC （VA140） cards handling 512 detector channels, or 4 ASIC （AGET） cards handling 256 detector channels, respectively. More FECs can be assembled in crates to handle thousands of detector channels.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
POLAR-2 is a gamma-ray burst(GRB)polarimeter that is designed to study the polarization in GRB radiation emissions,aiming to improve our knowledge of related mechanisms.POLAR-2 is expected to utilize an on-board polar...POLAR-2 is a gamma-ray burst(GRB)polarimeter that is designed to study the polarization in GRB radiation emissions,aiming to improve our knowledge of related mechanisms.POLAR-2 is expected to utilize an on-board polarimeter that is sensitive to soft X-rays(2-10 keV),called low-energy polarization detector.We have developed a new soft X-ray polari-zation detector prototype based on gas microchannel plates(GMCPs)and pixel chips(Topmetal).The GMCPs have bulk resistance,which prevents charging-up effects and ensures gain stability during operation.The detector is composed of low outgassing materials and is gas-sealed using a laser welding technique,ensuring long-term stability.A modulation factor of 41.28%±0.64% is obtained for a 4.5 keV polarized X-ray beam.A residual modulation of 1.96%±0.58% at 5.9 keV is observed for the entire sensitive area.展开更多
The variation among Chinese genotypes of Brassica napus L. for seed tocopherols content and their analysis using gas chromatography has not been comprehensively reported till to date. In the present study, the tocophe...The variation among Chinese genotypes of Brassica napus L. for seed tocopherols content and their analysis using gas chromatography has not been comprehensively reported till to date. In the present study, the tocopherol contents of four Chinese genotypes of Brassica napus L., namely, Gaoyou 605, Zhejiang 619, Zheshuang 758, and Zheshuang 72, were evaluated using three modified sample preparation protocols （P1, P2, and P3） for tocopherol extraction. These methods were distinguished as follows. Protocol one （P1） included the evaporation of solvent after extraction without silylation. Protocol two （P2） followed the direct supernatant collection after overnight extraction without drying and silylation. Protocol three （P3） included trimethylsilylation with N,O-bis（trimethylsilyl） trifluoroacetamide. Genotypic comparison of tocopherol and its isoforms revealed that Gaoyou 605 was dominant over the other genotypes with （140.5＋ 10.5）, （316.2＋ 9.2）, and （559.1＋ 24.3） ~tg g-~ of seed meal ct-, 7-, and total （T-） tocopherol, respectively, and a 0.44＋0.04 ^- to 7-tocopherol ratio. The comparison of the sample preparation protocols, on the other hand, suggests that P3 is the most suitable method for the tocopherol extraction from Brassica oilseeds and for the analysis of tocopherols using gas chromatography flame ionization detector （GC-FID）. Trimethylsilylation is the key step differentiating P3 from P1 and P2. Variations detected in tocopherol contents among the Chinese rapeseed （B. napus） genotypes signify the need to quantify a wide range of rapeseed germplasm for seed tocopherol dynamics in short and crop improvement in long.展开更多
Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and...Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.展开更多
The metal organic framework functionalized with sulfonic acid was combined with magnetic nanoparticles to fabricate a new nanocomposite(denoted as Fe3O4@PDA@Zr-SO3H).By combining with gas chromatography-electron captu...The metal organic framework functionalized with sulfonic acid was combined with magnetic nanoparticles to fabricate a new nanocomposite(denoted as Fe3O4@PDA@Zr-SO3H).By combining with gas chromatography-electron capture detector,the resulting Fe3O4@PDA@Zr-SO3H nanocomposite was successfully used as a high-efficiency adsorbent for pre-concentrating eight organochlorine pesticides from water sample in environment.Apart from the ability of fast separation,the as-prepared Fe3O4@PDA@Zr-SO3H nanocomposite also exhibited high adsorption capacity for organochlorine pesticides.With the use of optimal experimental conditions,the linear relationship can be obtained in the range of 0.05~300μg/L,the correlation coefficient was over 0.9978,and the relative standard deviation was located in 2.5%-7.7%.Moreover,the limit of detection and quantification was between0.005-0.016μg/L and 0.017~0.050μg/L.Finally,the nanocomposite was used for the determination of organochlorine pesticides from environmental water samples,and displayed the recovery of 82%-118%.展开更多
The samples of InxGa（1-x）As/In（0.52）Al（0.48）As two-dimensional electron gas（2DEG）are grown by molecular beam epitaxy（MBE）.In the sample preparation process,the In content and spacer layer thickness are chang...The samples of InxGa（1-x）As/In（0.52）Al（0.48）As two-dimensional electron gas（2DEG）are grown by molecular beam epitaxy（MBE）.In the sample preparation process,the In content and spacer layer thickness are changed and two kinds of methods,i.e.,contrast body doping andδ-doping are used.The samples are analyzed by the Hall measurements at 300 Kand 77 K.The InxGa1-xAs/In0.52Al0.48As 2DEG channel structures with mobilities as high as 10289 cm^2/V·s（300 K）and42040 cm^2/V·s（77 K）are obtained,and the values of carrier concentration（Nc）are 3.465×10^12/cm^2 and 2.502×10^12/cm^2,respectively.The THz response rates of In P-based high electron mobility transistor（HEMT）structures with different gate lengths at 300 K and 77 K temperatures are calculated based on the shallow water wave instability theory.The results provide a reference for the research and preparation of In P-based HEMT THz detectors.展开更多
A new detection system consisted of a flame ionization detector（FID） and a sulfur chemiluminescence detector（SCD） was developed for sensitive and interference free determination of total sulfur in natural gas by n...A new detection system consisted of a flame ionization detector（FID） and a sulfur chemiluminescence detector（SCD） was developed for sensitive and interference free determination of total sulfur in natural gas by non-separation gas chromatography. In this system, sulfur containing compounds and hydrocarbons were firstly burned in the FID using oxygen rich flame and converted to SO_2, CO_2 and H_2O, respectively. The products from FID were transported into the SCD with hydrogen rich atmosphere wherein only SO_2 could be reduced to SO and reacted with O_3 to produce characteristic chemiluminescence. Therefore, the chemiluminescence of CO found in conventional SCD were eliminated because CO_2 could not be reduced to CO under these conditions. The experimental parameters were systematically investigated. Limit of detection obtained by the proposed system is better than 0.5 mmol/mol for total sulfur and superior to those previously reported. The proposed method not only retains the advantages of the conventional SCD but also provides several unique advantages including no hydrocarbon interference, better stability, and easier calculation. The utility of this technique was demonstrated by the determination of total sulfur in real samples and two certified reference materials（GBW 06332 and GBW（E） 061320）.展开更多
Among various ionization detectors for gas chromatography(GC), the most promising one is perhaps the nonradioactive ionization detector which makes use of a microwave induced plasma(MIP). The use of MIP for gas chroma...Among various ionization detectors for gas chromatography(GC), the most promising one is perhaps the nonradioactive ionization detector which makes use of a microwave induced plasma(MIP). The use of MIP for gas chromatography was first studied by McCormack, et al. in 1965, Freeman developed a photoionization detector utilizing helium microwave discharge. In 1971, we developed a microwave展开更多
The software system, hardware system and performance principle of the gas detector were briefly described. A new method was developed for orientating and cali- brating the instrument. The method shows excellence in au...The software system, hardware system and performance principle of the gas detector were briefly described. A new method was developed for orientating and cali- brating the instrument. The method shows excellence in automation and intelligence, and presents simpler and more reliable new method for orientating and calibrating the nominal physical quantity of the nonlinear sensor.展开更多
A new analytical method for detecting butyltin in seawater is presented. In this method, the solid phase microextraction technique for pretreatment of the butyltin compound was used and a new type Flame Photometric De...A new analytical method for detecting butyltin in seawater is presented. In this method, the solid phase microextraction technique for pretreatment of the butyltin compound was used and a new type Flame Photometric Detector (FPD) was designed. Use of this method to determine the butyltin contents in Qingdao coast seawater yielded convincing results.展开更多
The relative response factors（RRFs） for noble gas（Ng） were determined on a pulsed discharge helium photoionization detector. Using ab initio method, the atomic orbitals of noble gas were calculated and used to det...The relative response factors（RRFs） for noble gas（Ng） were determined on a pulsed discharge helium photoionization detector. Using ab initio method, the atomic orbitals of noble gas were calculated and used to determine the number of ionizable electrons on the basis of the continuous emission of He2. The molar responses of noble gases is well correlated with the number of ionizable electrons.展开更多
A new type of solid-conversion gas detector is investigated for high energy X-ray industrial computed tomography (HECT). The conversion efficiency is calculated by using the EGSnrc Monte Carlo code on the Linux platfo...A new type of solid-conversion gas detector is investigated for high energy X-ray industrial computed tomography (HECT). The conversion efficiency is calculated by using the EGSnrc Monte Carlo code on the Linux platform to simulate the transport process of photons and electrons in the detector. The simulation results show that the conversion efficiency could be more than 65%, if the X-ray beam width is less than about 0.2 mm, and a tungsten slab with 0.2 mm thickness and 30 mm length is employed as a radiation conversion medium. Meanwhile the results indicate that this new detector has higher conversion efficiency as well as less volume. Theoretically this new kind of detector could take place of the traditional scintillation detector for HECT.展开更多
The accurate measurement of concentration is the basis for determining emission sources and sinks of nitrous oxide （N2O）. The detection of N2O showed that the presence of carbon dioxide （CO2） biased the N2O respon...The accurate measurement of concentration is the basis for determining emission sources and sinks of nitrous oxide （N2O）. The detection of N2O showed that the presence of carbon dioxide （CO2） biased the N2O response when pure nitrogen （N2） was used as a carrier gas for gas chromatography （GC） equipped with an electron capture detector （GC-ECD）. In this study, laboratory experiments were carried out to explore how the presence of CO2 interferes with the accurate determination of N2O. The aims were to address the extent of the influence to try and explain the underlying mechanism, and to uncover technical options for solving the problem. Three GC carrier gases are discussed： pure nitrogen （DN）; a mixture of argon and methane （AM）; and a high concentration CO2, which was introduced into the ECD cell with a low flow rate based on DN （DN-CO2）. The results show that when DN was used, the existence of CO2 in the ECD cell greatly enhanced the response of N2O, which increased with CO2 content and remained constant when the content reached a limit. Comparisons between the three methods show that the DN method is defective for the accurate determination of N2O. The bias is caused by different electron capture mechanisms of CO2 and N2O and depends heavily on the detector temperature. New GC carrier gas types with make-up gases that can remove the CO2-induced influence, such as the DN-CO2 and DN-CH4 methods reported in this paper, are recommended for the accurate measurement of N2O.展开更多
This study presents an electronics system for cosmic X-ray polarization detection(CXPD).The CXPD was designed as a high-sensitivity soft X-ray polarimeter with a measurement energy range of 2-10 keV carried by a CubeS...This study presents an electronics system for cosmic X-ray polarization detection(CXPD).The CXPD was designed as a high-sensitivity soft X-ray polarimeter with a measurement energy range of 2-10 keV carried by a CubeSat.A stable and functionally complete electronics system under power and space constraints is a key challenge.The complete CXPD electronics system(CXPDES)comprises hardware and firmware.CXPDES adopts a three-layer electronic board structure based on functionality and available space.Two gas pixel detectors(GPDs)were placed on the top layer board,and CXPDES provided the GPDs with voltages up to-4000 V.Each GPD signal was digitized,compressed,encoded,and stored before being transmitted to the ground.The CXPDES provided stable and high-speed communication based on a scheme that separated command and data transmission,and it supports the CXPDES in-orbit upgrade.In addition,environmental monitors,silicon photomultiplier(SiPM)triggers,power management,GPDs configuration,and mode switches were included in the overall operating logic of the CXPDES.The results obtained by testing the CXPDES showed that it satisfied all the requirements of CXPD.The CXPDES provides design experience and technological readiness for future large-area X-ray polarimetry missions.展开更多
The gas-sensitive film coated π-phase-shifted long-period fiber grating(LPFG),consisting of two same long-period fiber gratings cascaded by a regular fiber with length of half of the grating period,is proposed for ga...The gas-sensitive film coated π-phase-shifted long-period fiber grating(LPFG),consisting of two same long-period fiber gratings cascaded by a regular fiber with length of half of the grating period,is proposed for gas sensing.The sensitivity of the sensor is defined by the change rate of the transmission at specific wavelength with respect to the film refractive index.The qualitative and numerical analyses show that to get a high sensitivity,the optimal coupling strength of each long-period fiber grating is √2 π/4.With this coupling strength,the longer the grating is,the higher sensitivity the sensor has.By choosing appropriate grating period,a high sensitivity for the film with a certain refractive index and thickness can be attained.展开更多
A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed ...A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). The extract was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.展开更多
An optimized micro-gated terahertz detector with novel triple resonant antenna is presented.The novel resonant antenna operates at room temperature and shows more than a 700% increase in photocurrent response compared...An optimized micro-gated terahertz detector with novel triple resonant antenna is presented.The novel resonant antenna operates at room temperature and shows more than a 700% increase in photocurrent response compared to the conventional bowtie antenna.In finite-difference-time-domain simulations,we found the performance of the self-mixing GaN/AlGaN high electron mobility transistor detector is mainly dependent on the parameters L gs（the gap between the gate and the source/drain antenna） and L w（the gap between the source and drain antenna）.With the improved triple resonant antenna,an optimized micrometer-sized AlGaN/GaN high electron mobility transistor detector can achieve a high responsivity of 9.45×102 V/W at a frequency of 903 GHz at room temperature.展开更多
基金Project supported by the National Key R&D Program of China(Grant No.2023YFC2206502)the National Natural Science Foundation of China(Grant Nos.12175254 and 12227810)+1 种基金Guangdong Major Project of Basic and Applied Basic Research(Grant No.2023B0303000003)Guangdong Provincial Key Laboratory of Advanced Particle Detection Technology(Grant No.2024B1212010005)。
文摘The rapid growth of neutron flux has driven the development of^(3)He-free neutron detectors to satisfy the requirements of the neutron scattering instruments under construction or planned at the China Spallation Neutron Source(CSNS).Position-sensitive neutron detectors with a high counting rate and large area play an important role in the instruments performing neutron measurements in or close to the direct beam.The ceramic gas-electron-multiplier(GEM)detector serves as a promising solution,and considerable work has been done using the small-area GEM neutron detectors.In this article,we designed and constructed a detector prototype utilizing ceramic GEM foils with an effective area of about307 mm×307 mm.To evaluate and investigate their basic characteristics,the Monte Carlo(MC)tool FLUKA was employed and several neutron beam tests were conducted at CSNS.The simulated spatial resolution was basically in agreement with the measured value of 2.50±0.01 mm(FWHM).The wavelength spectra measurement was verified through comparisons with a commercial beam monitor.In addition,a detection efficiency of 4.7±0.1%was achieved for monoenergetic neutrons of 1.59 A wavelength.This is consistent with the simulated result.The results indicate that the large-area ceramic GEM detector is a good candidate to implement neutron beam measurements.Its efficiency can be improved in a cascading manner to approach that reached by traditional^(3)He detectors.
基金Supported by National Natural Science Foundation of China(11222552,11265003)
文摘The requirement of a large number of electronic channels poses a big challenge to the further applications of Micro-pattern Gas Detectors （MPGDs）. By using the redundancy that at least two neighboring strips record the signal of a particle, a novel method of encoded multiplexing readout for MPGDs is presented in this paper. The method offers a feasible and easily-extensible way of encoding and decoding, and can significantly reduce the number of readout channels. A verification test was carried out on a 5 cm×5 cm Thick Gas Electron Multiplier （THGEM） detector using a 8 keV Cu X-ray source with 100um slit, where 166 strips were read out by 21 encoded readout channels. The test results show good linearity in its position response, and the spatial resolution root-mean-square （RMS） of the test system is about 260um. This method has potential to build large area detectors and can be easily adapted to other detectors similar to MPGDs.
基金Supported by National Natural Science Foundation of China(11222552)
文摘A scalable readout system （SRS） is designed to provide a general solution for different micro-pattern gas detectors in various applications. The system mainly consists of three kinds of modules： the ASIC card, the adapter card and the front-end card （FEC）. The ASIC cards, mounted with particular ASIC chips, are designed for receiving detector signals. The adapter card is in charge of digitizing the output signals from several ASIC cards. The FEC, edged-mounted with the adapter, has field-programmable gate array （FPGA）-based reconfigurable logic and I/O interfaces, allowing users to choose different ASIC cards and adapters for different experiments, which expands the system to various applications. The FEC transfers data through Gigabit Ethernet protocol realized by a TCP processor （SiTCP） IP core in FPGA. By assembling a flexible number of FECs in parallel through Gigabit Ethernet, the readout system can be tailored to specific sizes to adapt to the experiment scales and readout requirements. In this paper, two kinds of multi-channel ASIC chip, VA140 and AGET, are applied to verify the scalability of this SRS architecture. Based on this VA140 or AGET SRS, one FEC covers 8 ASIC （VA140） cards handling 512 detector channels, or 4 ASIC （AGET） cards handling 256 detector channels, respectively. More FECs can be assembled in crates to handle thousands of detector channels.
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 Department of Physics and GXUNAOC Center for Astrophysics and Space Sciences,Guangxi UniversityThe National Natural Science Foundation of China(Nos.12027803,U1731239,12133003,12175241,U1938201,U1732266)the Guangxi Science Foundation(Nos.2018GXNSFGA281007,2018JJA110048).
文摘POLAR-2 is a gamma-ray burst(GRB)polarimeter that is designed to study the polarization in GRB radiation emissions,aiming to improve our knowledge of related mechanisms.POLAR-2 is expected to utilize an on-board polarimeter that is sensitive to soft X-rays(2-10 keV),called low-energy polarization detector.We have developed a new soft X-ray polari-zation detector prototype based on gas microchannel plates(GMCPs)and pixel chips(Topmetal).The GMCPs have bulk resistance,which prevents charging-up effects and ensures gain stability during operation.The detector is composed of low outgassing materials and is gas-sealed using a laser welding technique,ensuring long-term stability.A modulation factor of 41.28%±0.64% is obtained for a 4.5 keV polarized X-ray beam.A residual modulation of 1.96%±0.58% at 5.9 keV is observed for the entire sensitive area.
基金supported by the National Natural Science Foundation of China (30971700 and 31171463)Natural Science Foundation of Zhejiang Province (Z3100130)
文摘The variation among Chinese genotypes of Brassica napus L. for seed tocopherols content and their analysis using gas chromatography has not been comprehensively reported till to date. In the present study, the tocopherol contents of four Chinese genotypes of Brassica napus L., namely, Gaoyou 605, Zhejiang 619, Zheshuang 758, and Zheshuang 72, were evaluated using three modified sample preparation protocols （P1, P2, and P3） for tocopherol extraction. These methods were distinguished as follows. Protocol one （P1） included the evaporation of solvent after extraction without silylation. Protocol two （P2） followed the direct supernatant collection after overnight extraction without drying and silylation. Protocol three （P3） included trimethylsilylation with N,O-bis（trimethylsilyl） trifluoroacetamide. Genotypic comparison of tocopherol and its isoforms revealed that Gaoyou 605 was dominant over the other genotypes with （140.5＋ 10.5）, （316.2＋ 9.2）, and （559.1＋ 24.3） ~tg g-~ of seed meal ct-, 7-, and total （T-） tocopherol, respectively, and a 0.44＋0.04 ^- to 7-tocopherol ratio. The comparison of the sample preparation protocols, on the other hand, suggests that P3 is the most suitable method for the tocopherol extraction from Brassica oilseeds and for the analysis of tocopherols using gas chromatography flame ionization detector （GC-FID）. Trimethylsilylation is the key step differentiating P3 from P1 and P2. Variations detected in tocopherol contents among the Chinese rapeseed （B. napus） genotypes signify the need to quantify a wide range of rapeseed germplasm for seed tocopherol dynamics in short and crop improvement in long.
基金Supported by the National Natural Science Foundation of China(51474184)the Natural Science Foundation of the State Administration of Work Safety in China(2012-387,Sichuan-0021-2016AQ)
文摘Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.
文摘The metal organic framework functionalized with sulfonic acid was combined with magnetic nanoparticles to fabricate a new nanocomposite(denoted as Fe3O4@PDA@Zr-SO3H).By combining with gas chromatography-electron capture detector,the resulting Fe3O4@PDA@Zr-SO3H nanocomposite was successfully used as a high-efficiency adsorbent for pre-concentrating eight organochlorine pesticides from water sample in environment.Apart from the ability of fast separation,the as-prepared Fe3O4@PDA@Zr-SO3H nanocomposite also exhibited high adsorption capacity for organochlorine pesticides.With the use of optimal experimental conditions,the linear relationship can be obtained in the range of 0.05~300μg/L,the correlation coefficient was over 0.9978,and the relative standard deviation was located in 2.5%-7.7%.Moreover,the limit of detection and quantification was between0.005-0.016μg/L and 0.017~0.050μg/L.Finally,the nanocomposite was used for the determination of organochlorine pesticides from environmental water samples,and displayed the recovery of 82%-118%.
基金Project supported by the Foundation for Scientific Instrument and Equipment Development,Chinese Academy of Sciences(Grant No.YJKYYQ20170032)the National Natural Science Foundation of China(Grant No.61435012)
文摘The samples of InxGa（1-x）As/In（0.52）Al（0.48）As two-dimensional electron gas（2DEG）are grown by molecular beam epitaxy（MBE）.In the sample preparation process,the In content and spacer layer thickness are changed and two kinds of methods,i.e.,contrast body doping andδ-doping are used.The samples are analyzed by the Hall measurements at 300 Kand 77 K.The InxGa1-xAs/In0.52Al0.48As 2DEG channel structures with mobilities as high as 10289 cm^2/V·s（300 K）and42040 cm^2/V·s（77 K）are obtained,and the values of carrier concentration（Nc）are 3.465×10^12/cm^2 and 2.502×10^12/cm^2,respectively.The THz response rates of In P-based high electron mobility transistor（HEMT）structures with different gate lengths at 300 K and 77 K temperatures are calculated based on the shallow water wave instability theory.The results provide a reference for the research and preparation of In P-based HEMT THz detectors.
基金the National Science and Technology Supporting Plan(No.2013BAK12B04)for financial support
文摘A new detection system consisted of a flame ionization detector（FID） and a sulfur chemiluminescence detector（SCD） was developed for sensitive and interference free determination of total sulfur in natural gas by non-separation gas chromatography. In this system, sulfur containing compounds and hydrocarbons were firstly burned in the FID using oxygen rich flame and converted to SO_2, CO_2 and H_2O, respectively. The products from FID were transported into the SCD with hydrogen rich atmosphere wherein only SO_2 could be reduced to SO and reacted with O_3 to produce characteristic chemiluminescence. Therefore, the chemiluminescence of CO found in conventional SCD were eliminated because CO_2 could not be reduced to CO under these conditions. The experimental parameters were systematically investigated. Limit of detection obtained by the proposed system is better than 0.5 mmol/mol for total sulfur and superior to those previously reported. The proposed method not only retains the advantages of the conventional SCD but also provides several unique advantages including no hydrocarbon interference, better stability, and easier calculation. The utility of this technique was demonstrated by the determination of total sulfur in real samples and two certified reference materials（GBW 06332 and GBW（E） 061320）.
文摘Among various ionization detectors for gas chromatography(GC), the most promising one is perhaps the nonradioactive ionization detector which makes use of a microwave induced plasma(MIP). The use of MIP for gas chromatography was first studied by McCormack, et al. in 1965, Freeman developed a photoionization detector utilizing helium microwave discharge. In 1971, we developed a microwave
基金Key Project Sponsored by Science and Technology Office of Hebei(01220140D)
文摘The software system, hardware system and performance principle of the gas detector were briefly described. A new method was developed for orientating and cali- brating the instrument. The method shows excellence in automation and intelligence, and presents simpler and more reliable new method for orientating and calibrating the nominal physical quantity of the nonlinear sensor.
文摘A new analytical method for detecting butyltin in seawater is presented. In this method, the solid phase microextraction technique for pretreatment of the butyltin compound was used and a new type Flame Photometric Detector (FPD) was designed. Use of this method to determine the butyltin contents in Qingdao coast seawater yielded convincing results.
基金the National Natural Science Foundation of China(No.20503010)
文摘The relative response factors（RRFs） for noble gas（Ng） were determined on a pulsed discharge helium photoionization detector. Using ab initio method, the atomic orbitals of noble gas were calculated and used to determine the number of ionizable electrons on the basis of the continuous emission of He2. The molar responses of noble gases is well correlated with the number of ionizable electrons.
基金supported by the National Natural Science Foundation of China (No.60672098)the Tackling Key Problems of Science and Technology of ChongQing (No.CSTC2009AC3047)
文摘A new type of solid-conversion gas detector is investigated for high energy X-ray industrial computed tomography (HECT). The conversion efficiency is calculated by using the EGSnrc Monte Carlo code on the Linux platform to simulate the transport process of photons and electrons in the detector. The simulation results show that the conversion efficiency could be more than 65%, if the X-ray beam width is less than about 0.2 mm, and a tungsten slab with 0.2 mm thickness and 30 mm length is employed as a radiation conversion medium. Meanwhile the results indicate that this new detector has higher conversion efficiency as well as less volume. Theoretically this new kind of detector could take place of the traditional scintillation detector for HECT.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-204)the National Basic Research Program of China (No.2007CB407303)
文摘The accurate measurement of concentration is the basis for determining emission sources and sinks of nitrous oxide （N2O）. The detection of N2O showed that the presence of carbon dioxide （CO2） biased the N2O response when pure nitrogen （N2） was used as a carrier gas for gas chromatography （GC） equipped with an electron capture detector （GC-ECD）. In this study, laboratory experiments were carried out to explore how the presence of CO2 interferes with the accurate determination of N2O. The aims were to address the extent of the influence to try and explain the underlying mechanism, and to uncover technical options for solving the problem. Three GC carrier gases are discussed： pure nitrogen （DN）; a mixture of argon and methane （AM）; and a high concentration CO2, which was introduced into the ECD cell with a low flow rate based on DN （DN-CO2）. The results show that when DN was used, the existence of CO2 in the ECD cell greatly enhanced the response of N2O, which increased with CO2 content and remained constant when the content reached a limit. Comparisons between the three methods show that the DN method is defective for the accurate determination of N2O. The bias is caused by different electron capture mechanisms of CO2 and N2O and depends heavily on the detector temperature. New GC carrier gas types with make-up gases that can remove the CO2-induced influence, such as the DN-CO2 and DN-CH4 methods reported in this paper, are recommended for the accurate measurement of N2O.
基金supported by the National Natural Science Foundation of China (Nos.11875146,U1932143)National Key Research and Development Program of China (No.2020YFE0202002)。
文摘This study presents an electronics system for cosmic X-ray polarization detection(CXPD).The CXPD was designed as a high-sensitivity soft X-ray polarimeter with a measurement energy range of 2-10 keV carried by a CubeSat.A stable and functionally complete electronics system under power and space constraints is a key challenge.The complete CXPD electronics system(CXPDES)comprises hardware and firmware.CXPDES adopts a three-layer electronic board structure based on functionality and available space.Two gas pixel detectors(GPDs)were placed on the top layer board,and CXPDES provided the GPDs with voltages up to-4000 V.Each GPD signal was digitized,compressed,encoded,and stored before being transmitted to the ground.The CXPDES provided stable and high-speed communication based on a scheme that separated command and data transmission,and it supports the CXPDES in-orbit upgrade.In addition,environmental monitors,silicon photomultiplier(SiPM)triggers,power management,GPDs configuration,and mode switches were included in the overall operating logic of the CXPDES.The results obtained by testing the CXPDES showed that it satisfied all the requirements of CXPD.The CXPDES provides design experience and technological readiness for future large-area X-ray polarimetry missions.
基金supported by the National Natural Science Foundation of China (No.60777035)the Scientific Research Key Project Fund of the Ministry of Education (No.208040)the Shanghai Leading Academic Discipline Project (No.T0501)
文摘The gas-sensitive film coated π-phase-shifted long-period fiber grating(LPFG),consisting of two same long-period fiber gratings cascaded by a regular fiber with length of half of the grating period,is proposed for gas sensing.The sensitivity of the sensor is defined by the change rate of the transmission at specific wavelength with respect to the film refractive index.The qualitative and numerical analyses show that to get a high sensitivity,the optimal coupling strength of each long-period fiber grating is √2 π/4.With this coupling strength,the longer the grating is,the higher sensitivity the sensor has.By choosing appropriate grating period,a high sensitivity for the film with a certain refractive index and thickness can be attained.
基金Project supported by the National Tea Research Foundation, Kolkata,India
文摘A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). The extract was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.
基金Project supported by the National Basic Research Program of China (Grant No. G2009CB929303)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. Y0BAQ31001)+1 种基金the National Natural Science Foundation of China(Grant Nos. 60871077 and 61107093)the Visiting Professorship for Senior International Scientists of the Chinese Academy of Sciences (Grant No. 2010T2J07)
文摘An optimized micro-gated terahertz detector with novel triple resonant antenna is presented.The novel resonant antenna operates at room temperature and shows more than a 700% increase in photocurrent response compared to the conventional bowtie antenna.In finite-difference-time-domain simulations,we found the performance of the self-mixing GaN/AlGaN high electron mobility transistor detector is mainly dependent on the parameters L gs（the gap between the gate and the source/drain antenna） and L w（the gap between the source and drain antenna）.With the improved triple resonant antenna,an optimized micrometer-sized AlGaN/GaN high electron mobility transistor detector can achieve a high responsivity of 9.45×102 V/W at a frequency of 903 GHz at room temperature.
