In this study,a novel eutectic-reaction brazing of Al_(0.3)CoCrFeNi high-entropy alloys(HEAs)^(1)was investigated with a design of laminated Ni/Nb/Ni interlayers.The typical Al_(0.3)CoCrFeNi brazing seam consisted of ...In this study,a novel eutectic-reaction brazing of Al_(0.3)CoCrFeNi high-entropy alloys(HEAs)^(1)was investigated with a design of laminated Ni/Nb/Ni interlayers.The typical Al_(0.3)CoCrFeNi brazing seam consisted of proeutecticγ,the lamellar eutectic structure composed of face-centered cubic(FCC)phase(eutecticγ)and C14 Laves,as well as a few amounts of Nb based solid solution.A high density of nanoscale ordered L1_(2)(γ)phase was precipitated withinγphase matrix.With the brazing temperature raised from 1200 to 1320℃,the dissolution volume of Al_(0.3)CoCrFeNi alloy into Ni-Nb liquid was increased.The microstructure of the brazing seam changed from hypereutectic(blocky Laves+γphase)to eutectic(Laves+eutecticγ)to hypoeutectic structures(proeutecticγ+Laves/γeutectic structure).The shear strength of joints was increased gradually due to the formation of eutectic lamellae and the cellular growth of proeutecticγphase.The maximum shear strength of the joint brazed at 1320℃for 10 min was up to 592 MPa,reaching 95%of the base metal.The joint mainly ruptured in the soft proeutecticγphase in a ductile fracture mode.展开更多
Aconduction-cooled superconducting magnet with central field of 10Tand warmbore of 100 mmwas designed based on a Nb3Sn and two NbTi superconducting coils.At the first stage,the NbTi coils havebeen fabricated andtested...Aconduction-cooled superconducting magnet with central field of 10Tand warmbore of 100 mmwas designed based on a Nb3Sn and two NbTi superconducting coils.At the first stage,the NbTi coils havebeen fabricated andtested.Atwo-stage 4 KGifford-McMahon(GM) cryocooler withthe second-stage powerin1W,4.2Kis used to cool the magnet fromroomtemperature to 4 K.The superconducting magnet with thesame power supply has the operating current of 116A.The magnet can be rotated with a support frame to beoperated with either horizontal or vertical position.Apair of Bi-2223 hightemperature superconductingcurrentleads was employedto reduce heat leakage into 4.2Klevel.The NbTi coils reachto the operating current of120Awithout training effect to be observed duringchargingof the magnet during40 minutes chargingtime andgenerate the center field of 6.5T.The training effect inthe NbTi magnet directly cool-down by cryocooler andinter-winding support structure in magnet can be remarkablyimproved.The superconducting magnet has beenstably operatedfor more than 275 hours with 6.5T.In this paper,the detailed design,fabrication,stressanalysis and quench protection characteristics are presented.展开更多
The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of...The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×10^(35) cm^(–2)·s^(–1) or higher.The STCF will produce a data sample about a factor of 100 larger than that of the presentτ-charm factory—the BEPCII,providing a unique platform for exploring the asymmetry of matter-antimatter(charge-parity violation),in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions,as well as searching for exotic hadrons and physics beyond the Standard Model.The STCF project in China is under development with an extensive R&D program.This document presents the physics opportunities at the STCF,describes conceptual designs of the STCF detector system,and discusses future plans for detector R&D and physics case studies.展开更多
In this paper,we propose an approach to nucleon-pair approximation(NPA)with m-scheme bases,in which the collective nucleon pairs are represented in terms of antisymmetric matrices,and commutations between nucleon pair...In this paper,we propose an approach to nucleon-pair approximation(NPA)with m-scheme bases,in which the collective nucleon pairs are represented in terms of antisymmetric matrices,and commutations between nucleon pairs are given using a matrix multiplication that avoids angular-momentum couplings and recouplings.Therefore the present approach significantly simplifies the NPA computation.Furthermore,it is formulated on the same footing with and without isospin.展开更多
Background Liquid Argon(LAr)is used as a target material in several current and planned experiments related to dark matter direct searching and neutrino detection.Argon provides excellent pulse shape discrimination(PS...Background Liquid Argon(LAr)is used as a target material in several current and planned experiments related to dark matter direct searching and neutrino detection.Argon provides excellent pulse shape discrimination(PSD)capability,which could separate the electron recoil backgrounds from the expected nuclear recoil signals.As the next-generation photosensors,silicon photon multiplier(SiPM)is expected to replace traditional photon multiplier tubes.Purpose The purpose of this paper is to compare the PSD capability of a LAr detector between using SiPMs as photosensors and using PMTs as photosensors.Methods The PSD capability of a LAr detector is determined through the prompt fraction method,which relies on the analysis of output pulses.These pulses are generated using Monte Carlo simulation,incorporating real single photoelectron pulses obtained from a PMT or a SiPM.Results Three kinds of SiPMs and one kind of PMT have been used to compare the PSD capability of a LAr detector.The use of J-60035 SiPM results in a better PSD capability compared to the use of PMT as a photosensor,while using the other two kinds of SiPM deteriorates the PSD capability.Conclusion SiPM is a promising photosensor candidate for a LAr detector.The better energy resolution could help to improve its PSD capability,while the higher probabilities of cross-talk and after-pulse degrade its PSD capability.Notably,after-pulse has a more significant impact compared to cross-talk because after-pulse influences the energy distribution within the time window,while cross-talk primarily affects the energy resolution of the detector.展开更多
基金the National Natural Science Foundation of China(Nos.52175307,51775138 and U1737205)the Taishan Scholars Foundation of Shandong Province(No.tsqn201812128)。
文摘In this study,a novel eutectic-reaction brazing of Al_(0.3)CoCrFeNi high-entropy alloys(HEAs)^(1)was investigated with a design of laminated Ni/Nb/Ni interlayers.The typical Al_(0.3)CoCrFeNi brazing seam consisted of proeutecticγ,the lamellar eutectic structure composed of face-centered cubic(FCC)phase(eutecticγ)and C14 Laves,as well as a few amounts of Nb based solid solution.A high density of nanoscale ordered L1_(2)(γ)phase was precipitated withinγphase matrix.With the brazing temperature raised from 1200 to 1320℃,the dissolution volume of Al_(0.3)CoCrFeNi alloy into Ni-Nb liquid was increased.The microstructure of the brazing seam changed from hypereutectic(blocky Laves+γphase)to eutectic(Laves+eutecticγ)to hypoeutectic structures(proeutecticγ+Laves/γeutectic structure).The shear strength of joints was increased gradually due to the formation of eutectic lamellae and the cellular growth of proeutecticγphase.The maximum shear strength of the joint brazed at 1320℃for 10 min was up to 592 MPa,reaching 95%of the base metal.The joint mainly ruptured in the soft proeutecticγphase in a ductile fracture mode.
文摘Aconduction-cooled superconducting magnet with central field of 10Tand warmbore of 100 mmwas designed based on a Nb3Sn and two NbTi superconducting coils.At the first stage,the NbTi coils havebeen fabricated andtested.Atwo-stage 4 KGifford-McMahon(GM) cryocooler withthe second-stage powerin1W,4.2Kis used to cool the magnet fromroomtemperature to 4 K.The superconducting magnet with thesame power supply has the operating current of 116A.The magnet can be rotated with a support frame to beoperated with either horizontal or vertical position.Apair of Bi-2223 hightemperature superconductingcurrentleads was employedto reduce heat leakage into 4.2Klevel.The NbTi coils reachto the operating current of120Awithout training effect to be observed duringchargingof the magnet during40 minutes chargingtime andgenerate the center field of 6.5T.The training effect inthe NbTi magnet directly cool-down by cryocooler andinter-winding support structure in magnet can be remarkablyimproved.The superconducting magnet has beenstably operatedfor more than 275 hours with 6.5T.In this paper,the detailed design,fabrication,stressanalysis and quench protection characteristics are presented.
基金supported by the National Key R&D Program of China under Contract No.2022YFA1602200the International Partnership Program of the Chineses Academy of Sciences under Grant No.211134KYSB20200057the STCF Key Technology Research and Development Project.
文摘The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×10^(35) cm^(–2)·s^(–1) or higher.The STCF will produce a data sample about a factor of 100 larger than that of the presentτ-charm factory—the BEPCII,providing a unique platform for exploring the asymmetry of matter-antimatter(charge-parity violation),in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions,as well as searching for exotic hadrons and physics beyond the Standard Model.The STCF project in China is under development with an extensive R&D program.This document presents the physics opportunities at the STCF,describes conceptual designs of the STCF detector system,and discusses future plans for detector R&D and physics case studies.
基金the Sichuan Science and Technology Program(2019JDRC0017)Doctoral Program of Southwest University of Science and Technology(18zx7147)+4 种基金National Natural Science Foundation of China(11705100)Youth Innovations and Talents Project of Shandong Provincial Colleges,and Universities(201909118)Higher Educational Youth Innovation Science and Technology Program Shandong Province(2020KJJ004)National Natural Science Foundation of China(11975151,11675101,11961141003)MOE Key Lab for Particle Physics,Astrophysics and Cosmology for financial support。
文摘In this paper,we propose an approach to nucleon-pair approximation(NPA)with m-scheme bases,in which the collective nucleon pairs are represented in terms of antisymmetric matrices,and commutations between nucleon pairs are given using a matrix multiplication that avoids angular-momentum couplings and recouplings.Therefore the present approach significantly simplifies the NPA computation.Furthermore,it is formulated on the same footing with and without isospin.
基金supported by the National Natural Science Foundation of China(Grant Nos.12275289,11975257,and 12175247)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2023015)the National Key R&D Program of China(Grant No.2016YFA0400304).
文摘Background Liquid Argon(LAr)is used as a target material in several current and planned experiments related to dark matter direct searching and neutrino detection.Argon provides excellent pulse shape discrimination(PSD)capability,which could separate the electron recoil backgrounds from the expected nuclear recoil signals.As the next-generation photosensors,silicon photon multiplier(SiPM)is expected to replace traditional photon multiplier tubes.Purpose The purpose of this paper is to compare the PSD capability of a LAr detector between using SiPMs as photosensors and using PMTs as photosensors.Methods The PSD capability of a LAr detector is determined through the prompt fraction method,which relies on the analysis of output pulses.These pulses are generated using Monte Carlo simulation,incorporating real single photoelectron pulses obtained from a PMT or a SiPM.Results Three kinds of SiPMs and one kind of PMT have been used to compare the PSD capability of a LAr detector.The use of J-60035 SiPM results in a better PSD capability compared to the use of PMT as a photosensor,while using the other two kinds of SiPM deteriorates the PSD capability.Conclusion SiPM is a promising photosensor candidate for a LAr detector.The better energy resolution could help to improve its PSD capability,while the higher probabilities of cross-talk and after-pulse degrade its PSD capability.Notably,after-pulse has a more significant impact compared to cross-talk because after-pulse influences the energy distribution within the time window,while cross-talk primarily affects the energy resolution of the detector.
