Active target time projection chambers are state-of-the-art tools in the field of low-energy nuclear physics and are particularly suitable for experiments using low-intensity radioactive ion beams or gamma rays.The Fu...Active target time projection chambers are state-of-the-art tools in the field of low-energy nuclear physics and are particularly suitable for experiments using low-intensity radioactive ion beams or gamma rays.The Fudan multi-purpose active target time projection chamber(fMeta-TPC)with 2048 channels was developed to studyα-clustering nuclei.This study focused on the photonuclear reaction with a laser Compton scattering gamma source,particularly for the decay of the highly excitedαcluster state.The design of fMeta-TPC is described in this paper.A comprehensive evaluation of its offline performance was conducted using an ultraviolet laser and ^(241)Amαsource.The results showed that the intrinsic angular resolution of the detector was within 0.30°,and the detector had an energy resolution of 6.85%for 3.0 MeVαparticles.The gain uniformity of the detector was approximately 10%(RMS/Mean),as tested by the ^(55)Fe X-ray source.展开更多
Accurate cross sections of neutron induced fission reactions are required in the design of advanced nuclear systems and the development of fission theory.Time projection chambers(TPCs),with their track reconstruction ...Accurate cross sections of neutron induced fission reactions are required in the design of advanced nuclear systems and the development of fission theory.Time projection chambers(TPCs),with their track reconstruction and particle identification capabilities,are considered the best detectors for high-precision fission cross section measurements.The TPC developed by the back-streaming white neutron source(Back-n)team of the China Spallation Neutron Source(CSNS)was used as the fission fragment detector in measurements.In this study,the cross sections of the ^(232)Th(n,f)reaction at five neutron energies in the 4.50−5.40 MeV region were measured.The fission fragments and α particles were well identified using our TPC,which led to a higher detection efficiency of the fission fragments and smaller uncertainty of the measured cross sections.Ours is the first measurement of the ^(232)Th(n,f)reaction using a TPC for the detection of fission fragments.With uncertainties less than 5%,our cross sections are consistent with the data in different evaluation libraries,including JENDL-4.0,ROSFOND-2010,CENDL-3.2,ENDF/B-VⅢ.0,and BROND-3.1,whose uncertainties can be reduced after future improvement of the measurement.展开更多
The ^(12)C+^(12)C fusion reaction was studied in the range of E_(c.m.)=8.9 to 21 MeV using the active-target Time Projection Chamber.With full information on all tracks of the reaction products,cross sections of the^(...The ^(12)C+^(12)C fusion reaction was studied in the range of E_(c.m.)=8.9 to 21 MeV using the active-target Time Projection Chamber.With full information on all tracks of the reaction products,cross sections of the^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)channel and the ^(12)C(^(12)C,3a)^(12)C channel could be measured down to the level of a few milibarns.The ^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)reaction channel was determined to be 10_(-8)^(+24) mb at E_(c.m.)=11.1 MeV,supporting the direct a transfer reaction mechanism.The ^(12)C(^(12)C,3α)^(12)C reaction channel was studied for the first time using an exclusive measurement.Our result does not confirm the anomaly behavior reported in the previous inclusive measurement by Kolata et al.[Phys.Rev.C 21,579(1980)].Our comparisons with statistical model calculations suggest that the 3 a channel is dominated by the fusion evaporation process at E_(c.m.)>19 MeV.The additional contribution of the 3 a channel increases the fusion reaction cross section by 10% at energies above 20 MeV.We also find that an additional reaction mechanism is needed to explain the measured cross section at E_(c.m.)<15 MeV at which point the statistical model prediction vanishes.展开更多
A charged particle array named MATE-PA,which serves as an auxiliary detector system for a Multi-purpose Active-target Time projection chamber used in nuclear astrophysical and exotic beam Experiments(MATE),was constru...A charged particle array named MATE-PA,which serves as an auxiliary detector system for a Multi-purpose Active-target Time projection chamber used in nuclear astrophysical and exotic beam Experiments(MATE),was constructed.The array comprised of 20 single-sided strip-silicon detectors covering approximately 10%of the solid angle.The detectors facilitated the detection of reaction-induced charged particles that penetrate the active volume of the MATE.The performance of MATE-PA has been experimentally studied using an alpha source and a 36-MeV 14 N beam injected into the MATE chamber on the radioactive ion beam line in Lanzhou(RIBLL).The chamber was filled with a gas mixture of 95%4 He and 5%CO_(2) at a pressure of 500 mbar.The results indicated good separation of light-charged particles using the forward double-layer silicon detectors of MATE-PA.The energy resolution of the Si detectors was deduced to be approximately 1%(σ)for an energy loss of approximately 10 MeV caused by theαparticles.The inclusion of MATE-PA improves particle identification and increases the dynamic range of the kinetic energy of charged particles,particularly that of theαparticles,up to approximately 15 MeV.展开更多
Observing nuclear neutrinoless double beta (0vββ) decay would be a revolutionary result in particle physics.Observing such a decay would prove that the neutrinos are their own antiparticles,help to study the absolut...Observing nuclear neutrinoless double beta (0vββ) decay would be a revolutionary result in particle physics.Observing such a decay would prove that the neutrinos are their own antiparticles,help to study the absolute mass of neutrinos,explore the origin of their mass,and may explain the matter-antimatter asymmetry in our universe by lepton number violation.We propose developing a time projection chamber (TPC) using high-pressure ^(82)SeF_(6) gas and Topmetal silicon sensors for readout in the China Jinping Underground Laboratory (CJPL) to search for neutrinoless double beta decay of82Se,called the NvDEx experiment.Besides being located at CJPL with the world’s thickest rock shielding,NvDEx combines the advantages of the high Qββ(2.996 MeV) of82Se and the TPC’s ability to distinguish signal and background events using their different topological characteristics.This makes NvDEx unique,with great potential for low-background and high-sensitivity 0 vββsearches.NvDEx-100,a NvDEx experiment phase with 100 kg of SeF_(6)gas,is being built,with plans to complete installation at CJPL by 2025.This report introduces 0 vββ physics,the NvDEx concept and its advantages,and the schematic design of NvDEx-100,its subsystems,and background and sensitivity estimation.展开更多
Purpose Low-radioactive material screening is becoming essential for rare event search experiments,such as neutrinoless double beta decay and dark matter searches in underground laboratories.A gaseous time projection ...Purpose Low-radioactive material screening is becoming essential for rare event search experiments,such as neutrinoless double beta decay and dark matter searches in underground laboratories.A gaseous time projection chamber(TPC)can be used for such purposes with large active areas and high efficiency.Methods A gaseous TPC with a Micromegas readout plane of approximately 20×20 cm^(2)is successfully constructed for surface alpha contamination measurements.Results We have characterized the energy resolution,gain stability,and tracking capability with calibration sources.Conclusion With the unique track-related background suppression cuts of the gaseous TPC,we have established that the alpha background rate of the TPC is(0.13±0.03)×10^(−6)Bq/cm^(2),comparable to the leading commercial solutions.展开更多
“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the...“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the universe.Also,they are being increasingly used in other disciplines like nuclear power generation,life sciences,environmental sciences,medical sciences,etc.The article reviews the short history,recent development,and trend of nuclear detection and readout techniques,covering Semiconductor Detector,Gaseous Detector,Scintillation Detector,Cherenkov Detector,Transition Radiation Detector,and Readout Techniques.By explaining the principle and using examples,we hope to help the interested reader underst and this research field and bring exciting information to the community.展开更多
The charge readout of a liquid xenon(LXe)detector via proportional scintillation in the liquid phase was first realized by the Waseda group 40 years ago,but the technical challenges involved were overwhelming.Although...The charge readout of a liquid xenon(LXe)detector via proportional scintillation in the liquid phase was first realized by the Waseda group 40 years ago,but the technical challenges involved were overwhelming.Although the tests were successful,this method was finally discarded and eventually nearly forgotten.Currently,this approach is not considered for large LXe dark matter detectors.Instead,the dual-phase technology was selected despite many limitations and challenges.In two independent studies,two groups from Columbia University and Shanghai Jiao Tong University reevaluated proportional scintillation in the liquid phase.Both studies established the merits for very large LXe detectors,but the Columbia group also encountered apparent limitations,namely the shadowing of the light by the anode wires,and a dependence of the pulse shape on the drift path of the electrons in the anode region.The differences between the two studies,however,are not intrinsic to the technique,but a direct consequence of the chosen geometry.Taking the geometrical differences into account,the results match without ambiguity.They also agree with the original results from the Waseda group.展开更多
基金supported by the National Key R&D Program of China(Nos.2022YFA1602402,2020YFE0202001,2023YFA1606900)the National Natural Science Foundation of China(NSFC)(Nos.12235003,11835002,11925502,11705031,12275053,12147101).
文摘Active target time projection chambers are state-of-the-art tools in the field of low-energy nuclear physics and are particularly suitable for experiments using low-intensity radioactive ion beams or gamma rays.The Fudan multi-purpose active target time projection chamber(fMeta-TPC)with 2048 channels was developed to studyα-clustering nuclei.This study focused on the photonuclear reaction with a laser Compton scattering gamma source,particularly for the decay of the highly excitedαcluster state.The design of fMeta-TPC is described in this paper.A comprehensive evaluation of its offline performance was conducted using an ultraviolet laser and ^(241)Amαsource.The results showed that the intrinsic angular resolution of the detector was within 0.30°,and the detector had an energy resolution of 6.85%for 3.0 MeVαparticles.The gain uniformity of the detector was approximately 10%(RMS/Mean),as tested by the ^(55)Fe X-ray source.
基金Supported by the National Natural Science Foundation of China(12075008)the Key Laboratory of Nuclear Data foundation(6142A08200103)+1 种基金the Basic and Applied Basic Research Foundation of Guangdong Province,China(2021B1515120027)the State Key Laboratory of Nuclear Physics and Technology,Peking University(NPT2021KFJ57)。
文摘Accurate cross sections of neutron induced fission reactions are required in the design of advanced nuclear systems and the development of fission theory.Time projection chambers(TPCs),with their track reconstruction and particle identification capabilities,are considered the best detectors for high-precision fission cross section measurements.The TPC developed by the back-streaming white neutron source(Back-n)team of the China Spallation Neutron Source(CSNS)was used as the fission fragment detector in measurements.In this study,the cross sections of the ^(232)Th(n,f)reaction at five neutron energies in the 4.50−5.40 MeV region were measured.The fission fragments and α particles were well identified using our TPC,which led to a higher detection efficiency of the fission fragments and smaller uncertainty of the measured cross sections.Ours is the first measurement of the ^(232)Th(n,f)reaction using a TPC for the detection of fission fragments.With uncertainties less than 5%,our cross sections are consistent with the data in different evaluation libraries,including JENDL-4.0,ROSFOND-2010,CENDL-3.2,ENDF/B-VⅢ.0,and BROND-3.1,whose uncertainties can be reduced after future improvement of the measurement.
基金Supported in part by the Strategic Priority Research Program of Chinese Academy of Sciences(XDB34020200)the National Key Research and Development program(MOST 2016YFA0400501)from the Ministry of Science and Technology of China+2 种基金the State Key Laboratory of Nuclear Physics and Technology,PKU(NPT2020KFY06)the National Natural Science Foundation of China(U1632142,12175156),the National Natural Science Foundation of China(11905260)the Western Light Project of Chinese Academy of Sciences。
文摘The ^(12)C+^(12)C fusion reaction was studied in the range of E_(c.m.)=8.9 to 21 MeV using the active-target Time Projection Chamber.With full information on all tracks of the reaction products,cross sections of the^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)channel and the ^(12)C(^(12)C,3a)^(12)C channel could be measured down to the level of a few milibarns.The ^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)reaction channel was determined to be 10_(-8)^(+24) mb at E_(c.m.)=11.1 MeV,supporting the direct a transfer reaction mechanism.The ^(12)C(^(12)C,3α)^(12)C reaction channel was studied for the first time using an exclusive measurement.Our result does not confirm the anomaly behavior reported in the previous inclusive measurement by Kolata et al.[Phys.Rev.C 21,579(1980)].Our comparisons with statistical model calculations suggest that the 3 a channel is dominated by the fusion evaporation process at E_(c.m.)>19 MeV.The additional contribution of the 3 a channel increases the fusion reaction cross section by 10% at energies above 20 MeV.We also find that an additional reaction mechanism is needed to explain the measured cross section at E_(c.m.)<15 MeV at which point the statistical model prediction vanishes.
基金supported by the National Natural Science Foundation of China(Nos.12175280 and 12250610193)the National Key R&D Program of China(No.2016YFA0400500)+1 种基金the support of the CAS“Light of West China”Programthe support of the Natural Science Foundation of Gansu(No.23JRRA676)。
文摘A charged particle array named MATE-PA,which serves as an auxiliary detector system for a Multi-purpose Active-target Time projection chamber used in nuclear astrophysical and exotic beam Experiments(MATE),was constructed.The array comprised of 20 single-sided strip-silicon detectors covering approximately 10%of the solid angle.The detectors facilitated the detection of reaction-induced charged particles that penetrate the active volume of the MATE.The performance of MATE-PA has been experimentally studied using an alpha source and a 36-MeV 14 N beam injected into the MATE chamber on the radioactive ion beam line in Lanzhou(RIBLL).The chamber was filled with a gas mixture of 95%4 He and 5%CO_(2) at a pressure of 500 mbar.The results indicated good separation of light-charged particles using the forward double-layer silicon detectors of MATE-PA.The energy resolution of the Si detectors was deduced to be approximately 1%(σ)for an energy loss of approximately 10 MeV caused by theαparticles.The inclusion of MATE-PA improves particle identification and increases the dynamic range of the kinetic energy of charged particles,particularly that of theαparticles,up to approximately 15 MeV.
基金This work was supported by the National Key Research and Development Program of China(Nos.2021YFA1601300 and 2022YFA1604703)From-0-to-1 Original Innovation Program of Chinese Academy of Sciences(No.ZDBS-LY-SLH014)+1 种基金International Partner Program of Chinese Academy of Sciences(No.GJHZ2067)National Natural Science Foundation of China Youth Science Fund Project(No.12105110).
文摘Observing nuclear neutrinoless double beta (0vββ) decay would be a revolutionary result in particle physics.Observing such a decay would prove that the neutrinos are their own antiparticles,help to study the absolute mass of neutrinos,explore the origin of their mass,and may explain the matter-antimatter asymmetry in our universe by lepton number violation.We propose developing a time projection chamber (TPC) using high-pressure ^(82)SeF_(6) gas and Topmetal silicon sensors for readout in the China Jinping Underground Laboratory (CJPL) to search for neutrinoless double beta decay of82Se,called the NvDEx experiment.Besides being located at CJPL with the world’s thickest rock shielding,NvDEx combines the advantages of the high Qββ(2.996 MeV) of82Se and the TPC’s ability to distinguish signal and background events using their different topological characteristics.This makes NvDEx unique,with great potential for low-background and high-sensitivity 0 vββsearches.NvDEx-100,a NvDEx experiment phase with 100 kg of SeF_(6)gas,is being built,with plans to complete installation at CJPL by 2025.This report introduces 0 vββ physics,the NvDEx concept and its advantages,and the schematic design of NvDEx-100,its subsystems,and background and sensitivity estimation.
基金supported by the grant from the Ministry of Science and Technology of China(No.2016YFA0400302)the grant U1965201 from the National Natural Sciences Foundation of ChinaWe appreciate the support from the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP).
文摘Purpose Low-radioactive material screening is becoming essential for rare event search experiments,such as neutrinoless double beta decay and dark matter searches in underground laboratories.A gaseous time projection chamber(TPC)can be used for such purposes with large active areas and high efficiency.Methods A gaseous TPC with a Micromegas readout plane of approximately 20×20 cm^(2)is successfully constructed for surface alpha contamination measurements.Results We have characterized the energy resolution,gain stability,and tracking capability with calibration sources.Conclusion With the unique track-related background suppression cuts of the gaseous TPC,we have established that the alpha background rate of the TPC is(0.13±0.03)×10^(−6)Bq/cm^(2),comparable to the leading commercial solutions.
基金supported by the National Natural Science Foundation of China(No.12222512,U2032209,12075045,12335011,1875097,11975257,62074146,11975115,12205374,12305210,11975292,12005276,12005278,12375193,12227805,12235012,12375191,12005279)the National Key Research and Development Program of China(2021YFA1601300)+13 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB34000000)the CAS Pioneer Hundred Talent Programthe CAS“Light of West China”Programthe Natural Science Foundation of Liaoning Province(No.101300261)the Dalian Science and Technology Innovation Fund(2023JJ12GX013)the Special Projects of the Central Government in Guidance of Local Science and Technology Development(Research and development of three-dimensional prospecting technology based on Cosmic-ray muons)(YDZX20216200001297)the Science and Technology Planning Project of Gansu(20JR10RA645)the Lanzhou University Talent Cooperation Research Funds sponsored by both Lanzhou City(561121203)the Gansu provincial science and technology plan projects for talents(054000029)the Beijing Natural Science Foundation(No.1232033)the Beijing Hope Run Special Fund of Cancer Foundation of China(No.LC2021B23)the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030008)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.GJJSTD20210009)the Youth Innovation Promotion Association CAS(2021450)。
文摘“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the universe.Also,they are being increasingly used in other disciplines like nuclear power generation,life sciences,environmental sciences,medical sciences,etc.The article reviews the short history,recent development,and trend of nuclear detection and readout techniques,covering Semiconductor Detector,Gaseous Detector,Scintillation Detector,Cherenkov Detector,Transition Radiation Detector,and Readout Techniques.By explaining the principle and using examples,we hope to help the interested reader underst and this research field and bring exciting information to the community.
基金supported by a Grant from the Ministry of Science and Technology of China(No.2016YFA0400301)。
文摘The charge readout of a liquid xenon(LXe)detector via proportional scintillation in the liquid phase was first realized by the Waseda group 40 years ago,but the technical challenges involved were overwhelming.Although the tests were successful,this method was finally discarded and eventually nearly forgotten.Currently,this approach is not considered for large LXe dark matter detectors.Instead,the dual-phase technology was selected despite many limitations and challenges.In two independent studies,two groups from Columbia University and Shanghai Jiao Tong University reevaluated proportional scintillation in the liquid phase.Both studies established the merits for very large LXe detectors,but the Columbia group also encountered apparent limitations,namely the shadowing of the light by the anode wires,and a dependence of the pulse shape on the drift path of the electrons in the anode region.The differences between the two studies,however,are not intrinsic to the technique,but a direct consequence of the chosen geometry.Taking the geometrical differences into account,the results match without ambiguity.They also agree with the original results from the Waseda group.
