Neutron resonance imaging(NRI)has recently emerged as an appealing technique for neutron radiography.Its complexity surpasses that of conventional transmission imaging,as it requires a high demand for both a neutron s...Neutron resonance imaging(NRI)has recently emerged as an appealing technique for neutron radiography.Its complexity surpasses that of conventional transmission imaging,as it requires a high demand for both a neutron source and detector.Consequently,the progression of NRI technology has been sluggish since its inception in the 1980s,particularly considering the limited studies analyzing the neutron energy range above keV.The white neutron source(Back-n)at the China Spallation Neutron Source(CSNS)provides favorable beam conditions for the development of the NRI technique over a wide neutron energy range from eV to MeV.Neutron-sensitive microchannel plates(MCP)have emerged as a cutting-edge tool in the field of neutron detection owing to their high temporal and spatial resolutions,high detection efficiency,and low noise.In this study,we report the development of a 10B-doped MCP detector,along with its associated electronics,data processing system,and NRI experiments at the Back-n.Individual heavy elements such as gold,silver,tungsten,and indium can be easily identified in the transmission images by their characteristic resonance peaks in the 1–100 eV energy range;the more difficult medium-weight elements such as iron,copper,and aluminum with resonance peaks in the 1–100 keV energy range can also be identified.In particular,results in the neutron energy range of dozens of keV(Aluminum)are reported here for the first time.展开更多
The back-streaming white-neutron beamline(Back-n)of the China Spallation Neutron Source is an essential neutronresearch platform built for the study of nuclear data,neutron physics,and neutron applications.Many types ...The back-streaming white-neutron beamline(Back-n)of the China Spallation Neutron Source is an essential neutronresearch platform built for the study of nuclear data,neutron physics,and neutron applications.Many types of cross-sectional neutron-reaction measurements have been performed at Back-n since early 2018.These measurements have shown that a significant number of gamma rays can be transmitted to the experimental stations of Back-n along with the neutron beam.These gamma rays,commonly referred to as in-beam gamma rays,can induce a non-negligible experimental background in neutron-reaction measurements.Studying the characteristics of in-beam gamma rays is important for understanding the experimental background.However,measuring in-beam gamma rays is challenging because most gamma-ray detectors are sensitive to neutrons;thus,discriminating between neutron-induced signals and those from in-beam gamma rays is difficult.In this study,we propose the use of the black resonance filter method and a CeBr_(3) scintillation detector to measure the characteristics of the in-beam gamma rays of Back-n.Four types of black resonance filters,^(181)Ta,^(59)Co,^(nat)Ag,and^(nat)Cd,were used in this measurement.The time-of-flight(TOF)technique was used to select the detector signals remaining in the absorption region of the TOF spectra,which were mainly induced by in-beam gamma rays.The energy distribution and flux of the in-beam gamma rays of Back-n were determined by analyzing the deposited energy spectra of the CeBr_(3) scintillation detector and using Monte Carlo simulations.Based on the results of this study,the background contributions from in-beam gamma rays in neutron-reaction measurements at Back-n can be reasonably evaluated,which is beneficial for enhancing both the experimental methodology and data analysis.展开更多
Neutron-sensitive microchannel plates(nMCPs)have applications in neutron detection,including energy spectrum measurements,neutron-induced cross sections,and neutron imaging.10B-doped MCPs(B-MCPs)have attracted signifi...Neutron-sensitive microchannel plates(nMCPs)have applications in neutron detection,including energy spectrum measurements,neutron-induced cross sections,and neutron imaging.10B-doped MCPs(B-MCPs)have attracted significant attention owing to their potential for exhibiting a high neutron detection efficiency over a large neutron energy range.Good spatial and temporal resolutions are useful for neutron energy-resolved imaging.However,their practical applications still face many technical challenges.In this study,a B-MCP with 10 mol%10B was tested for its response to wide-energy neutrons from eV to MeV at the Back-n white neutron source at the China Spallation Neutron Source.The neutron detection efficiency was calibrated at 1 eV,which is approximately 300 times that of an ordinary MCP and indicates the success of 10 B doping.The factors that caused the reduction in the detection efficiency were simulated and discussed.The neutron energy spectrum obtained using B-MCP was compared with that obtained by other measurement methods,and showed very good consistency for neutron energies below tens of keV.The response is more complicated at higher neutron energy,at which point the elastic and nonelastic reactions of all nuclides of B-MCP gradually become dominant.This is beneficial for the detection of neutrons,as it compensates for the detection efficiency of B-MCP for high-energy neutrons.展开更多
Purpose Back-n is a white neutron beamline at China spallation neutron source,which was established in the year of 2018.It is a powerful facility for nuclear data measurement,neutron detector calibration,and radiation...Purpose Back-n is a white neutron beamline at China spallation neutron source,which was established in the year of 2018.It is a powerful facility for nuclear data measurement,neutron detector calibration,and radiation effect research.Method A series of detectors were built for different experiments,including beam monitoring,beam profile measurement,neutron induced secondaries(fission fragments,light charged particles and gamma)cross section measurement,and neutron resonance radiography,etc.A common digitization electronics and a cluster-based DAQ were developed for these detector systems.Most detectors have been employed at Back-n and serviced for experiments from the beginning of the beamline running.Results and conclusion As an overview of detectors of Back-n,the details of the detector design and the experiment performing are described in this paper.Some developing systems,e.g.,MTPC and B-MCP,are also included.展开更多
基金supported by the National Natural Science Foundation of China(No.12035017)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515030074)。
文摘Neutron resonance imaging(NRI)has recently emerged as an appealing technique for neutron radiography.Its complexity surpasses that of conventional transmission imaging,as it requires a high demand for both a neutron source and detector.Consequently,the progression of NRI technology has been sluggish since its inception in the 1980s,particularly considering the limited studies analyzing the neutron energy range above keV.The white neutron source(Back-n)at the China Spallation Neutron Source(CSNS)provides favorable beam conditions for the development of the NRI technique over a wide neutron energy range from eV to MeV.Neutron-sensitive microchannel plates(MCP)have emerged as a cutting-edge tool in the field of neutron detection owing to their high temporal and spatial resolutions,high detection efficiency,and low noise.In this study,we report the development of a 10B-doped MCP detector,along with its associated electronics,data processing system,and NRI experiments at the Back-n.Individual heavy elements such as gold,silver,tungsten,and indium can be easily identified in the transmission images by their characteristic resonance peaks in the 1–100 eV energy range;the more difficult medium-weight elements such as iron,copper,and aluminum with resonance peaks in the 1–100 keV energy range can also be identified.In particular,results in the neutron energy range of dozens of keV(Aluminum)are reported here for the first time.
基金supported by the Youth Talent Program of China National Nuclear Corporationthe Continuous-Support Basic Scientific Research Project(BJ010261223282)+1 种基金the National Natural Science Foundation of China(No.11790321)the Research and development project of China National Nuclear Corporation。
文摘The back-streaming white-neutron beamline(Back-n)of the China Spallation Neutron Source is an essential neutronresearch platform built for the study of nuclear data,neutron physics,and neutron applications.Many types of cross-sectional neutron-reaction measurements have been performed at Back-n since early 2018.These measurements have shown that a significant number of gamma rays can be transmitted to the experimental stations of Back-n along with the neutron beam.These gamma rays,commonly referred to as in-beam gamma rays,can induce a non-negligible experimental background in neutron-reaction measurements.Studying the characteristics of in-beam gamma rays is important for understanding the experimental background.However,measuring in-beam gamma rays is challenging because most gamma-ray detectors are sensitive to neutrons;thus,discriminating between neutron-induced signals and those from in-beam gamma rays is difficult.In this study,we propose the use of the black resonance filter method and a CeBr_(3) scintillation detector to measure the characteristics of the in-beam gamma rays of Back-n.Four types of black resonance filters,^(181)Ta,^(59)Co,^(nat)Ag,and^(nat)Cd,were used in this measurement.The time-of-flight(TOF)technique was used to select the detector signals remaining in the absorption region of the TOF spectra,which were mainly induced by in-beam gamma rays.The energy distribution and flux of the in-beam gamma rays of Back-n were determined by analyzing the deposited energy spectra of the CeBr_(3) scintillation detector and using Monte Carlo simulations.Based on the results of this study,the background contributions from in-beam gamma rays in neutron-reaction measurements at Back-n can be reasonably evaluated,which is beneficial for enhancing both the experimental methodology and data analysis.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515030074)the National Natural Science Foundation of China(No.12035017)。
文摘Neutron-sensitive microchannel plates(nMCPs)have applications in neutron detection,including energy spectrum measurements,neutron-induced cross sections,and neutron imaging.10B-doped MCPs(B-MCPs)have attracted significant attention owing to their potential for exhibiting a high neutron detection efficiency over a large neutron energy range.Good spatial and temporal resolutions are useful for neutron energy-resolved imaging.However,their practical applications still face many technical challenges.In this study,a B-MCP with 10 mol%10B was tested for its response to wide-energy neutrons from eV to MeV at the Back-n white neutron source at the China Spallation Neutron Source.The neutron detection efficiency was calibrated at 1 eV,which is approximately 300 times that of an ordinary MCP and indicates the success of 10 B doping.The factors that caused the reduction in the detection efficiency were simulated and discussed.The neutron energy spectrum obtained using B-MCP was compared with that obtained by other measurement methods,and showed very good consistency for neutron energies below tens of keV.The response is more complicated at higher neutron energy,at which point the elastic and nonelastic reactions of all nuclides of B-MCP gradually become dominant.This is beneficial for the detection of neutrons,as it compensates for the detection efficiency of B-MCP for high-energy neutrons.
基金support provided by the National KeyR&DProgram of China(Grant No.2016YFA0401600).
文摘Purpose Back-n is a white neutron beamline at China spallation neutron source,which was established in the year of 2018.It is a powerful facility for nuclear data measurement,neutron detector calibration,and radiation effect research.Method A series of detectors were built for different experiments,including beam monitoring,beam profile measurement,neutron induced secondaries(fission fragments,light charged particles and gamma)cross section measurement,and neutron resonance radiography,etc.A common digitization electronics and a cluster-based DAQ were developed for these detector systems.Most detectors have been employed at Back-n and serviced for experiments from the beginning of the beamline running.Results and conclusion As an overview of detectors of Back-n,the details of the detector design and the experiment performing are described in this paper.Some developing systems,e.g.,MTPC and B-MCP,are also included.
