In the future, the Very Large Area gamma-ray Space Telescope is expected to observe high-energy electrons and gamma rays in the MeV to TeV range with unprecedented acceptance. As part of the detector suite, a high-ene...In the future, the Very Large Area gamma-ray Space Telescope is expected to observe high-energy electrons and gamma rays in the MeV to TeV range with unprecedented acceptance. As part of the detector suite, a high-energy imaging calorimeter(HEIC) is currently being developed as a homogeneous calorimeter that utilizes long bismuth germanate(BGO) scintillation crystals as both absorbers and detectors. To accurately measure the energy deposition in the BGO bar of HEIC, a highdynamic-range readout method using a silicon photomultiplier(SiPM) and multiphotodiode(PD) with different active areas has been proposed. A prototype readout system that adopts multichannel charge measurement ASICs was also developed to read out the combined system of SiPMs and PDs. Preliminary tests confirmed the feasibility of the readout scheme, which is expected to have a dynamic range close to 10~6.展开更多
We report the laser-chirp controlled terahertz(THz) wave generation from two-color-laser-induced air plasma.Our experimental results reveal that the THz wave is affected by both the laser energy and chirp,leading to r...We report the laser-chirp controlled terahertz(THz) wave generation from two-color-laser-induced air plasma.Our experimental results reveal that the THz wave is affected by both the laser energy and chirp,leading to radiation minima that can be quantitatively reconstructed using the linear-dipole-array model.The phase difference between the two colors,determined by the chirp and intensity of the laser,can account for the radiation minima.Furthermore,we observe an asynchronous variation in the generated THz spectrum,which suggests a THz frequency-dependent phase matching between the laser pulse and THz wave.These results highlight the importance of laser chirp during the THz wave generation and demonstrate the possibility of modulating the THz yields and spectrum through chirping the incident laser pulse.This work can provide valuable insights into the mechanism of plasma-based THz wave generation and offer a unique means to control THz emissions.展开更多
A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-ge...A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China.Characterized by low energy loss and good performances of timing and position measurements,it would be located at focal planes in fragment separator HFRS for position monitoring,beam turning,Bq measurement,and trajectory reconstruction.Moreover,it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(BqDETOF)method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event basis.Most importantly,the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci,and position measurements at a dispersive focus of HFRS,thus making it possible to use two complementary mass measurement methods[isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(BqTOF)at the beam-line HFRS]in one single experimental run.展开更多
With the rapid development of automated visual analysis,visual analysis systems have become a popular research topic in the field of computer vision and automated analysis.Visual analysis systems can assist humans to ...With the rapid development of automated visual analysis,visual analysis systems have become a popular research topic in the field of computer vision and automated analysis.Visual analysis systems can assist humans to detect anomalous events(e.g.,fighting,walking alone on the grass,etc).In general,the existing methods for visual anomaly detection are usually based on an autoencoder architecture,i.e.,reconstructing the current frame or predicting the future frame.Then,the reconstruction error is adopted as the evaluation metric to identify whether an input is abnormal or not.The flaws of the existing methods are that abnormal samples can also be reconstructed well.In this paper,inspired by the human memory ability,we propose a novel deep neural network(DNN)based model termed cognitive memory-augmented network(CMAN)for the visual anomaly detection problem.The proposed CMAN model assumes that the visual analysis system imitates humans to remember normal samples and then distinguishes abnormal events from the collected videos.Specifically,in the proposed CMAN model,we introduce a memory module that is able to simulate the memory capacity of humans and a density estimation network that can learn the data distribution.The reconstruction errors and the novelty scores are used to distinguish abnormal events from videos.In addition,we develop a two-step scheme to train the proposed model so that the proposed memory module and the density estimation network can cooperate to improve performance.Comprehensive experiments evaluated on various popular benchmarks show the superiority and effectiveness of the proposed CMAN model for visual anomaly detection comparing with the state-of-the-arts methods.The implementation code of our CMAN method can be accessed at https://github.com/CMANcode/CMAN_pytorch.展开更多
Cold seeps spread worldwide along the continental margins,which are closely related to the exploration of gas hydrates.Cold-seep carbonates have been reported to record the nature of seepage,including fluid source,sed...Cold seeps spread worldwide along the continental margins,which are closely related to the exploration of gas hydrates.Cold-seep carbonates have been reported to record the nature of seepage,including fluid source,sedimentary environment,and variation of seepage activity.We investigated the morphology,mineralogy,element compositions,and carbon and oxygen isotopes of 15 cold-seep carbonates collected from the Shenhu area,and compared them with 2 carbonates from the Haima cold seep,the South China Sea(SCS),to promote our knowledge of cold-seep system in SCS.Most of the Shenhu carbonates exhibit crust morphology,and some are in the form of chimneys and blocks.Their absolute(20%–65%)and relative carbonate mineral contents(mainly aragonite and calcite,with minor samples containing dolomite)vary significantly,indicating the multi-stage methane leakage in our study area.Some samples show a slight negative Ce anomaly,suggesting either the mixing of seawater or variation of the redox condition during the precipitation;the cooccurrence of strongly enriched U and Mo demonstrates anoxic condition during precipitation.The mixed genetic methane source was interpreted by δ^(13)C of the Shenhu carbonates to range from-22.34‰to-59.30‰Vienna PeeDee Belemnite(VPDB),and the slight ^(18)O-enrichment imprinted on the carbonates suggests the possible influence from hydrate dissociation.The Haima carbonates,with biogenic methane as the main gas source,were presumably formed in a stronger fluid flux by compared with our Shenhu samples.展开更多
Isochronous mass spectrometry(IMS)of heavyion storage rings is a powerful tool for the mass measurements of short-lived nuclei.In IMS experiments,masses are determined through precision measurements of the revolution ...Isochronous mass spectrometry(IMS)of heavyion storage rings is a powerful tool for the mass measurements of short-lived nuclei.In IMS experiments,masses are determined through precision measurements of the revolution times of the ions stored in the ring.However,the revolution times cannot be resolved for particles with nearly the same mass-to-charge(m/q)ratios.To overcome this limitation and to extract the accurate revolution times for such pairs of ion species with very close m/q ratios,in our early work on particle identification,we analyzed the amplitudes of the timing signals from the detector based on the emission of secondary electrons.Here,the previous data analysis method is further improved by considering the signal amplitudes,detection efficiencies,and number of stored ions in the ring.A sensitive Z-dependent parameter is introduced in the data analysis,leading to a better resolution of ^(34)Ar^(18+) and ^(51)Co^(27+) with A/Z=17/9.The mean revolution times of ^(34)Ar^(18+) and ^(51)Co^(27+) are deduced,although their time difference is merely 1.8 ps.The uncorrected,overlapped peak of these ions has a full width at half maximum of 7.7 ps.The mass excess of ^(51)Co was determined to be-27;332e41T keV,which is in agreement with the previous value of-27;342e48T keV.展开更多
To improve the vibration isolation performance of suspensions,various new structural forms of suspensions have been proposed.However,there is uncertainty in these new structure suspensions,so the deterministic researc...To improve the vibration isolation performance of suspensions,various new structural forms of suspensions have been proposed.However,there is uncertainty in these new structure suspensions,so the deterministic research cannot refect the performance of the suspension under actual operating conditions.In this paper,a quasi-zero stifness isolator is used in automotive suspensions to form a new suspension−quasi-zero stifness air suspension(QZSAS).Due to the strong nonlinearity and structural complexity of quasi-zero stifness suspensions,changes in structural parameters may cause dramatic changes in suspension performance,so it is of practical importance to study the efect of structural parameter uncertainty on the suspension performance.In order to solve this problem,three suspension structural parameters d_(0),L_(0) and Pc_(0) are selected as random variables,and the polynomial chaos expansion(PCE)theory is used to solve the suspension performance parameters.The sensitivity of the performance parameters to diferent structural parameters was discussed and analyzed in the frequency domain.Furthermore,a multi-objective optimization of the structural parameters d_(0),L_(0) and Pc_(0) of QZSAS was performed with the mean and variance of the root-mean-square(RMS)acceleration values as the optimization objectives.The optimization results show that there is an improvement of about 8%−1_(0)%in the mean value and about 4_(0)%−55%in the standard deviation of acceleration(RMS)values.This paper verifes the feasibility of the PCE method for solving the uncertainty problem of complex nonlinear systems,which provide a reference for the future structural design and optimization of such suspension systems.展开更多
Ammonium perchlorate(AP)is the component with the highest content in composite propellants,and it plays a crucial role in propellant performance.In view of the effects of low-temperature AP thermal decomposition on th...Ammonium perchlorate(AP)is the component with the highest content in composite propellants,and it plays a crucial role in propellant performance.In view of the effects of low-temperature AP thermal decomposition on thermal safety and combustion characteristics,porous ammonium perchlorate(PAP)samples with different mass losses were first prepared by thermal convection heating,and the structures were characterized and analysed.Second,the effects of decomposition degree on the thermal decomposition characteristics of PAP were studied by DSC-TG.Finally,the combustion characteristics of AP/Al binary mixtures were tested with high-speed photography and in a sealed bomb.The results showed that low-temperature decomposition of AP resulted in formation of porous structures for AP particles.The pores first appeared near the surfaces of the particles and began from multiple points at the same time.The pores increased in size to approximately 5 mm and then expanded,and finally,the AP particles were full of pores.After partial decomposition,the crystal structure of AP remained unchanged,but the low and high decomposition temperatures decreased obviously.The decomposition rate accelerated.Due to the porous structure of PAP,the combustion rate of the AP/Al system increased obviously with increasing decomposition of AP.The relationship between the combustion rate and the mass loss was approximately linear under open conditions,and it was exponential for a high-pressure environment.A computational model of the combustion process for the AP/Al binary system was established to explain the effects of pore structure and pressure on the combustion process.展开更多
Bi_(2)O_(2)Se has been proved to be a promising candidate for electronic and optoelectronic devices due to their unique physical properties.However,it is still a great challenge to construct the heterostructures with ...Bi_(2)O_(2)Se has been proved to be a promising candidate for electronic and optoelectronic devices due to their unique physical properties.However,it is still a great challenge to construct the heterostructures with direct epitaxy of hetero semiconductor materials on Bi_(2)O_(2)Se nanosheets.Here,a two-step chemical vapor deposition(CVD)route was used to directly grow the CsPbBr_(3)nanoplate-Bi_(2)O_(2)Se nanosheet hetero structures.The CsPbBr_(3)nanoplates were selectively grown on the Bi_(2)O_(2)Se nanosheet along the edges,where the dangling bonds provide the nucleation sites.The epitaxial relationships between CsPbBr3 and Bi_(2)O_(2)Se were determined as[200]_(Bi_(2)O_(2)Se)‖[110]_(CsPbBr_(3))and[110]_(Bi_(2)O_(2)Se)‖[200]_(CsPbBr_(3))by transmission electron microscopy characterization.The photoluminescence(PL)results reveal that the formation of heterostructures results in the remarkable PL quenching due to the type-Ⅰband arrangement at CsPbBr_(3)/Bi_(2)O_(2)Se interface,which was confirmed by ultraviolet photoelectron spectroscopy(UPS)and Kelvin probe measurements,and makes the photogenerated carriers transfer from CsPbBr_(3)to Bi_(2)O_(2)Se.Importantly,the photodetectors based on the heterostructures exhibit a 4-time increase in the responsivity compared to those based on the pristine Bi_(2)O_(2)Se sheets,and the fast rise and decay time in microsecond.These results indicate that the direct epitaxy of the CsPbBr_(3)plates on the Bi_(2)O_(2)Se sheet may improve the optoelectronic performance of Bi_(2)O_(2)Se based devices.展开更多
基金Foundation of China (Nos. 12227805, U1831206, 12103095, 12235012, 12273120, and 11973097)the Scientific Instrument Developing Project of the Chinese Academy of Sciences (No. GJJSTD20210009)。
文摘In the future, the Very Large Area gamma-ray Space Telescope is expected to observe high-energy electrons and gamma rays in the MeV to TeV range with unprecedented acceptance. As part of the detector suite, a high-energy imaging calorimeter(HEIC) is currently being developed as a homogeneous calorimeter that utilizes long bismuth germanate(BGO) scintillation crystals as both absorbers and detectors. To accurately measure the energy deposition in the BGO bar of HEIC, a highdynamic-range readout method using a silicon photomultiplier(SiPM) and multiphotodiode(PD) with different active areas has been proposed. A prototype readout system that adopts multichannel charge measurement ASICs was also developed to read out the combined system of SiPMs and PDs. Preliminary tests confirmed the feasibility of the readout scheme, which is expected to have a dynamic range close to 10~6.
基金supported by the National Natural Science Foundation of China (Grant Nos.12174449,12225511,T2241002,12074250,11991073,12135009,61988102,and 61971397)the National Key Research and Development Program of China (Grant Nos.2019YFA0307703 and 2018YFB2202500)。
文摘We report the laser-chirp controlled terahertz(THz) wave generation from two-color-laser-induced air plasma.Our experimental results reveal that the THz wave is affected by both the laser energy and chirp,leading to radiation minima that can be quantitatively reconstructed using the linear-dipole-array model.The phase difference between the two colors,determined by the chirp and intensity of the laser,can account for the radiation minima.Furthermore,we observe an asynchronous variation in the generated THz spectrum,which suggests a THz frequency-dependent phase matching between the laser pulse and THz wave.These results highlight the importance of laser chirp during the THz wave generation and demonstrate the possibility of modulating the THz yields and spectrum through chirping the incident laser pulse.This work can provide valuable insights into the mechanism of plasma-based THz wave generation and offer a unique means to control THz emissions.
基金supported by the National Natural Science Foundation of China(Nos.11605248,11605249,11605267,and 11805032.)
文摘A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China.Characterized by low energy loss and good performances of timing and position measurements,it would be located at focal planes in fragment separator HFRS for position monitoring,beam turning,Bq measurement,and trajectory reconstruction.Moreover,it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(BqDETOF)method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event basis.Most importantly,the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci,and position measurements at a dispersive focus of HFRS,thus making it possible to use two complementary mass measurement methods[isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(BqTOF)at the beam-line HFRS]in one single experimental run.
基金the National Natural Science Foundation of China(61976049,62072080,U20B2063)the Fundamental Research Funds for the Central Universities(ZYGX2019Z015)+1 种基金the Sichuan Science and Technology Program,China(2018GZDZX0032,2019ZDZX0008,2019YFG0003,2019YFG0533,2020YFS0057)Dongguan Songshan Lake Introduction Program of Leading Innovative and Entrepreneurial Talents.Recommended by Associate Editor Huimin Lu.
文摘With the rapid development of automated visual analysis,visual analysis systems have become a popular research topic in the field of computer vision and automated analysis.Visual analysis systems can assist humans to detect anomalous events(e.g.,fighting,walking alone on the grass,etc).In general,the existing methods for visual anomaly detection are usually based on an autoencoder architecture,i.e.,reconstructing the current frame or predicting the future frame.Then,the reconstruction error is adopted as the evaluation metric to identify whether an input is abnormal or not.The flaws of the existing methods are that abnormal samples can also be reconstructed well.In this paper,inspired by the human memory ability,we propose a novel deep neural network(DNN)based model termed cognitive memory-augmented network(CMAN)for the visual anomaly detection problem.The proposed CMAN model assumes that the visual analysis system imitates humans to remember normal samples and then distinguishes abnormal events from the collected videos.Specifically,in the proposed CMAN model,we introduce a memory module that is able to simulate the memory capacity of humans and a density estimation network that can learn the data distribution.The reconstruction errors and the novelty scores are used to distinguish abnormal events from videos.In addition,we develop a two-step scheme to train the proposed model so that the proposed memory module and the density estimation network can cooperate to improve performance.Comprehensive experiments evaluated on various popular benchmarks show the superiority and effectiveness of the proposed CMAN model for visual anomaly detection comparing with the state-of-the-arts methods.The implementation code of our CMAN method can be accessed at https://github.com/CMANcode/CMAN_pytorch.
基金Supported by the Guangdong Province Marine Economic Development(Six Major Marine Industries)Special Fund Project(No.[2021]No.58)the National Key R&D Program of China(No.2018YFC0310000)the National Natural Science Foundation of China(Nos.41776056,42076054)。
文摘Cold seeps spread worldwide along the continental margins,which are closely related to the exploration of gas hydrates.Cold-seep carbonates have been reported to record the nature of seepage,including fluid source,sedimentary environment,and variation of seepage activity.We investigated the morphology,mineralogy,element compositions,and carbon and oxygen isotopes of 15 cold-seep carbonates collected from the Shenhu area,and compared them with 2 carbonates from the Haima cold seep,the South China Sea(SCS),to promote our knowledge of cold-seep system in SCS.Most of the Shenhu carbonates exhibit crust morphology,and some are in the form of chimneys and blocks.Their absolute(20%–65%)and relative carbonate mineral contents(mainly aragonite and calcite,with minor samples containing dolomite)vary significantly,indicating the multi-stage methane leakage in our study area.Some samples show a slight negative Ce anomaly,suggesting either the mixing of seawater or variation of the redox condition during the precipitation;the cooccurrence of strongly enriched U and Mo demonstrates anoxic condition during precipitation.The mixed genetic methane source was interpreted by δ^(13)C of the Shenhu carbonates to range from-22.34‰to-59.30‰Vienna PeeDee Belemnite(VPDB),and the slight ^(18)O-enrichment imprinted on the carbonates suggests the possible influence from hydrate dissociation.The Haima carbonates,with biogenic methane as the main gas source,were presumably formed in a stronger fluid flux by compared with our Shenhu samples.
基金This work was supported by the National Key R&D Program of China(Nos.2016YFA0400504 and 2018YFA0404401)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB34000000)+4 种基金the National Natural Science Foundation of China(Nos.11905261,11805032,11975280,and 11605248)the CAS "Light of West China" Program,the China Postdoctoral Science Foundation(No.2019M660250)the FRIB-CSC Fellowship,China(No.201704910964)the International Postdoctoral Exchange Fellowship Program 2017 by the Office of China Postdoctoral Council(No.60 Document of OCPC,2017)the European Research Council(ERC)under the European Union’s Horizon 2020 Research and Innovation Programme(No.682841 "ASTRUm").
文摘Isochronous mass spectrometry(IMS)of heavyion storage rings is a powerful tool for the mass measurements of short-lived nuclei.In IMS experiments,masses are determined through precision measurements of the revolution times of the ions stored in the ring.However,the revolution times cannot be resolved for particles with nearly the same mass-to-charge(m/q)ratios.To overcome this limitation and to extract the accurate revolution times for such pairs of ion species with very close m/q ratios,in our early work on particle identification,we analyzed the amplitudes of the timing signals from the detector based on the emission of secondary electrons.Here,the previous data analysis method is further improved by considering the signal amplitudes,detection efficiencies,and number of stored ions in the ring.A sensitive Z-dependent parameter is introduced in the data analysis,leading to a better resolution of ^(34)Ar^(18+) and ^(51)Co^(27+) with A/Z=17/9.The mean revolution times of ^(34)Ar^(18+) and ^(51)Co^(27+) are deduced,although their time difference is merely 1.8 ps.The uncorrected,overlapped peak of these ions has a full width at half maximum of 7.7 ps.The mass excess of ^(51)Co was determined to be-27;332e41T keV,which is in agreement with the previous value of-27;342e48T keV.
基金Supported by National Natural Science Foundation of China(Grant No.51875256)Open Platform Fund of Hunan Institute of Technology of China(Grant No.KFA20009)Hong Kong,Macao and Taiwan Science and Technology Cooperation Project in Jiangsu Province of China(Grant No.BZ2020050)。
文摘To improve the vibration isolation performance of suspensions,various new structural forms of suspensions have been proposed.However,there is uncertainty in these new structure suspensions,so the deterministic research cannot refect the performance of the suspension under actual operating conditions.In this paper,a quasi-zero stifness isolator is used in automotive suspensions to form a new suspension−quasi-zero stifness air suspension(QZSAS).Due to the strong nonlinearity and structural complexity of quasi-zero stifness suspensions,changes in structural parameters may cause dramatic changes in suspension performance,so it is of practical importance to study the efect of structural parameter uncertainty on the suspension performance.In order to solve this problem,three suspension structural parameters d_(0),L_(0) and Pc_(0) are selected as random variables,and the polynomial chaos expansion(PCE)theory is used to solve the suspension performance parameters.The sensitivity of the performance parameters to diferent structural parameters was discussed and analyzed in the frequency domain.Furthermore,a multi-objective optimization of the structural parameters d_(0),L_(0) and Pc_(0) of QZSAS was performed with the mean and variance of the root-mean-square(RMS)acceleration values as the optimization objectives.The optimization results show that there is an improvement of about 8%−1_(0)%in the mean value and about 4_(0)%−55%in the standard deviation of acceleration(RMS)values.This paper verifes the feasibility of the PCE method for solving the uncertainty problem of complex nonlinear systems,which provide a reference for the future structural design and optimization of such suspension systems.
基金the National Natural Science Foundation of China(Grant No.11772058).
文摘Ammonium perchlorate(AP)is the component with the highest content in composite propellants,and it plays a crucial role in propellant performance.In view of the effects of low-temperature AP thermal decomposition on thermal safety and combustion characteristics,porous ammonium perchlorate(PAP)samples with different mass losses were first prepared by thermal convection heating,and the structures were characterized and analysed.Second,the effects of decomposition degree on the thermal decomposition characteristics of PAP were studied by DSC-TG.Finally,the combustion characteristics of AP/Al binary mixtures were tested with high-speed photography and in a sealed bomb.The results showed that low-temperature decomposition of AP resulted in formation of porous structures for AP particles.The pores first appeared near the surfaces of the particles and began from multiple points at the same time.The pores increased in size to approximately 5 mm and then expanded,and finally,the AP particles were full of pores.After partial decomposition,the crystal structure of AP remained unchanged,but the low and high decomposition temperatures decreased obviously.The decomposition rate accelerated.Due to the porous structure of PAP,the combustion rate of the AP/Al system increased obviously with increasing decomposition of AP.The relationship between the combustion rate and the mass loss was approximately linear under open conditions,and it was exponential for a high-pressure environment.A computational model of the combustion process for the AP/Al binary system was established to explain the effects of pore structure and pressure on the combustion process.
基金the National Natural Science Foundation of China(Grant No.51772088)Hunan Provincial Innovation Foundation for Postgraduate,China(Grant No.CX20200422)。
文摘Bi_(2)O_(2)Se has been proved to be a promising candidate for electronic and optoelectronic devices due to their unique physical properties.However,it is still a great challenge to construct the heterostructures with direct epitaxy of hetero semiconductor materials on Bi_(2)O_(2)Se nanosheets.Here,a two-step chemical vapor deposition(CVD)route was used to directly grow the CsPbBr_(3)nanoplate-Bi_(2)O_(2)Se nanosheet hetero structures.The CsPbBr_(3)nanoplates were selectively grown on the Bi_(2)O_(2)Se nanosheet along the edges,where the dangling bonds provide the nucleation sites.The epitaxial relationships between CsPbBr3 and Bi_(2)O_(2)Se were determined as[200]_(Bi_(2)O_(2)Se)‖[110]_(CsPbBr_(3))and[110]_(Bi_(2)O_(2)Se)‖[200]_(CsPbBr_(3))by transmission electron microscopy characterization.The photoluminescence(PL)results reveal that the formation of heterostructures results in the remarkable PL quenching due to the type-Ⅰband arrangement at CsPbBr_(3)/Bi_(2)O_(2)Se interface,which was confirmed by ultraviolet photoelectron spectroscopy(UPS)and Kelvin probe measurements,and makes the photogenerated carriers transfer from CsPbBr_(3)to Bi_(2)O_(2)Se.Importantly,the photodetectors based on the heterostructures exhibit a 4-time increase in the responsivity compared to those based on the pristine Bi_(2)O_(2)Se sheets,and the fast rise and decay time in microsecond.These results indicate that the direct epitaxy of the CsPbBr_(3)plates on the Bi_(2)O_(2)Se sheet may improve the optoelectronic performance of Bi_(2)O_(2)Se based devices.
