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A polarized^(3)He system based on metastability-exchange optical pumping

Science China(physics,Mechanics & Astronomy) 2024年第7期67卷 72-81页

作者： Yuting Wang Liangyong Wu Kaiyuan Zhang Mei Peng Siyu Chen Haiyang Yan state key laboratory of nuclear physics and technology School of PhysicsPeking UniversityBeijing 100871China institute of nuclear physics and Chemistry China Academy of Engineering PhysicsMianyang 621900China key laboratory of nuclear physics and ion-beam Application(MOE) Fudan UniversityShanghai 200433China key laboratory of Neutron physics Institute of Nuclear Physics and ChemistryChina Academy of Engineering PhysicsMianyang 621900China

Hyperpolarized^(3)He nuclei have emerged as a significantly important approach in quantum precision measurement techniques,with extensive applications in fundamental physics,magnetometry,metrology,and *** this study,we report on the design and implementation of a^(3)He polarization system at the China Mianyang Research Reactor(CMRR),utilizing the metastabilityexchange optical pumping(MEOP)*** employed a Merritt coil system consisting of four square coils to furnish a uniform holding *** deployed a 2 W fiber laser to pump the metastable^(3)He atoms and conducted free induction decay(FID)detection of the polarized^(3)He nuclei using both pickup coil and optical *** the optical method,we used a50 m W linearly polarized distributed Bragg reflector(DBR)laser as the *** applied transverse light absorption polarimetry to measure the absolute nuclear polarization of the ground-state^(3)*** have developed cell fabrication capabilities at the CMRR,and cells at various pressures ranging from 100 to 1000 Pa have been fabricated and *** a typical borosilicate cell with 100 Pa pressure,the absolute polarization is measured as Pn≈70%,and the transverse relaxation time is estimated as T2≈0.5 ***,we constructed a few aluminosilicate cells,each carefully filled with pure^(3)He at a pressure of 100 ***,we conducted a comprehensive evaluation of their performance in the context of MEOP.

关键词： metastability exchange optical pumping polarized^(3)He magnetic resonance

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Structure and 2p decay mechanism of^(18)Mg

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nuclear Science and Techniques 2024年第6期35卷 145-154页

作者： Long Zhou De-Qing Fang Si-Min Wang Hui Hua key laboratory of nuclear physics and ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China Shanghai Research Center for Theoretical nuclear physics NSFC and Fudan UniversityShanghai 200438China School of physics and state key laboratory of nuclear physics and technology Peking UniversityBeijing 100871China

The recently discovered,extremely proton-rich nuclide 18 Mg exhibits ground-state decay via two sequential two-proton(2p)emissions through the intermediate nucleus,*** study investigates the structure and the initial 2p decay mechanism of^(18)Mgby examining the density and correlations of the valence protons using a three-body Gamow coupled-channel *** results show that the ground state of^(18)Mgis significantly influenced by the continuum,resulting in a significant s-wave ***,based on the current framework,this does not lead to a significant deviation in mirror symmetry in either the structure or spectroscopy of the 18Mg-18C ***,the time evolution analysis of the^(18)Mgground state suggests a simultaneous 2p emission during the first step of *** observed nucleon-nucleon correlations align with those of the light-mass 2p emitters,indicating a consistent decay behavior within this nuclear region.

关键词： Structure of^(18)Mg Two-proton decay Proton-proton correlation

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Production and test of sPHENIX W/SciFiber electromagnetic calorimeter blocks in China

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nuclear Science and Techniques 2024年第8期35卷 167-176页

作者： Xiao‑Zhou Yu Xi‑Yang Wang Wei‑Hu Ma Shi‑Hong Fu Peng‑Fei Sun Jin‑Xing Song Wan‑Bing He Yang Shen Long Ma Jin‑Hui Chen Huan‑Zhong Huang Si‑Guang Wang Jing Zhou Xiao‑Mei Li institute of Modern physics Fudan UniversityShanghai 200433China key laboratory of nuclear physics and ion‑Beam Application(MOE) Fudan UniversityShanghai 200433China Science and technology on nuclear Data laboratory China Institute of Atomic EnergyBeijing 102413China Department of physics and Astronomy University of CaliforniaLos AngelesCA 90095USA state key laboratory of nuclear physics and technology School of PhysicsPeking UniversityBeijing 100871China

The sPHENIX experiment is a new generation of large acceptance detectors at the relativistic heavy ion collider at Brookhaven National laboratory,with scientific goals focusing on probing the strongly interacting Quark–Gluon plasma with hard probes of jets,open heavy flavor particles,andγ*** EMCal detector,which covers the pseudo-rapidity region of|η|≤1.1,is an essential subsystem of *** this study,we focused on producing and testing EMCal blocks covering a pseudo-rapidity of|η|∈[0.8,1.1].These,in conjunction with the central pseudo-rapidity EMCal blocks,significantly enhance the sPHENIX physics capability of the jet andγparticle *** this paper,the detector module production and testing of sPHENIX W-powder/scintillating fiber(W/ScFi)electromagnetic calorimeter blocks are *** selection of the tungsten powder,mold fabrication,QA procedures,and cosmic ray test results are discussed.

关键词： sPHENIX Tungsten/scintillating fiber electromagnetic calorimeter Cosmic ray test

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Digital signal acquisition system for complex nuclear reaction experiments

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nuclear Science and Techniques 2024年第1期35卷 124-133页

作者： Wei-Liang Pu Yan-Lin Ye Jian-Ling Lou Jia-Hao Chen School of physics and state key laboratory of nuclear physics and technology Peking UniversityBeijing 100871China institute of Applied physics and Computational Mathematics Beijing 100094China

A digital data-acquisition system based on XIA LLC products was used in a complex nuclear reaction experiment using radioactive ion beams.A flexible trigger system based on a field-programmable gate array(FPGA)parametrization was developed to adapt to different experimental sizes.A user-friendly interface was implemented,which allows converting script language expressions into FPGA internal control *** proposed digital system can be combined with a conventional analog data acquisition system to provide more *** performance of the combined system was veri-fied using experimental data.

关键词： Digital signal acquisition system Trigger Programmable logic Timestamp

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laboratory observation of electron energy distribution near three-dimensional magnetic nulls

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Plasma Science and technology 2024年第3期26卷 46-52页

作者：何任川徐田超杨肖易肖池阶张祖煜袁瑞鑫王晓钢郭志彬余修铭盖跃 state key laboratory of nuclear physics and technology School of PhysicsPeking UniversityBeijing 100871People's Republic of China Department of physics Harbin Institute of TechnologyHarbin 150001People's Republic of China

The acceleration of electrons near three-dimensional(3D)magnetic nulls is crucial to the energy conversion mechanism in the 3D magnetic reconnection *** explore electron acceleration in a 3D magnetic null topology,we constructed a pair of 3D magnetic nulls in the PKU Plasma Test(PPT)device and observed acceleration of electrons near magnetic *** study measured the plasma floating potential and ion density profiles around the 3D magnetic *** potential wells near nulls may be related to the energy variations of electrons,so we measured the electron distribution functions(EDFs)at different spatial *** axial variation of EDF shows that the electrons deviate from the Maxwell distribution near magnetic *** scanning probes that can directionally measure and theoretically analyze based on curve fitting,the variations of EDFs are linked to the changes of plasma potential under 3D magnetic null *** kinetic energy of electrons accelerated by the electric field is 6 eV(v_(e)~7v_(Alfvén-e))and the scale of the region where accelerating electrons exist is in the order of serval electron skin depths.

关键词： electron acceleration EEDF 3D magnetic null magnetic reconnection

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Inward particle transport driven by biased endplate in a cylindrical magnetized plasma

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Plasma Science and technology 2024年第3期26卷 126-130页

作者：盖跃徐田超肖池阶郭志彬王晓钢何任川杨肖易张祖煜袁瑞鑫 state key laboratory of nuclear physics and technology School of PhysicsPeking UniversityBeijing 100871People's Republic of China Department of physics Harbin Institute of TechnologyHarbin 150001People's Republic of China

The inward particle transport is associated with the formation of peaked density profiles,which contributes to improve the fusion rate and the realization of steady-state *** active control of inward particle transport is considered as one of the most critical issues of magnetic confinement ***,it is realized preliminarily by adding a biased endplate in the Peking University Plasma Test(PPT)*** results reveal that the inward particle flux increases with the bias voltage of the *** is also found that the profile of radial electric field(Er)shear is flattened by the increased bias *** velocity fluctuations affect the inward particle more than density fluctuations,and the frequency of the dominant mode driving inward particle flux increases with the biased voltage applied to the *** experimental results in the PPT device provide a method to actively control the inward particle flux using a biased endplate and enrich the understanding of the relationship between E_(r)×B shear and turbulence transport.

关键词： inward particle transport biased endplate turbulent transport

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Cross section measurement for the^(232)Th(n,f)reaction in the 4.50−5.40 MeV region using a time projection chamber

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Chinese physics C 2024年第10期48卷 157-167页

作者： Haofan Bai Han Yi Yankun Sun Yiwei Hu Jie Liu Zepeng Wu Cong Xia Wenkai Ren Wentian Cao Tieshuan Fan Guohui Zhang Ruirui Fan Yang Li Wei Jiang Yonghao Chen You Lv Changjun Ning Weihua Jia Zhiyong Zhang Haolei Chen Zhen Chen Maoyuan Zhao Changqing Feng Shubin Liu state key laboratory of nuclear physics and technology Institute of Heavy Ion PhysicsPeking UniversityBeijing 100871China institute of High Energy physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523803China National key laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear TechnologyXi'an 710024China Department of nuclear Science and technology School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China state key laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China Department of Modern physics University of Science and Technology of ChinaHefei 230026China

Accurate cross sections of neutron induced fission reactions are required in the design of advanced nuclear systems and the development of fission *** projection chambers(TPCs),with their track reconstruction and particle identification capabilities,are considered the best detectors for high-precision fission cross section *** 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 *** 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 *** 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 *** is the first measurement of the ^(232)Th(n,f)reaction using a TPC for the detection of fission *** 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.

关键词： ^(232)Th(n,f)fission cross section time projection chamber(TPC) ^(232)Th

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Implications of neutron skin measurements on Skyrme equations of state

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Chinese physics C 2024年第6期48卷 155-161页

作者：管大为裴俊琛蒋崇基 state key laboratory of nuclear physics and technology School of PhysicsPeking UniversityBeijing 100871China Southern Center for nuclear-Science Theory(SCNT) Institute of Modern PhysicsChinese Academy of SciencesHuizhou 516000China

The recent measurements of neutron skins via parity violation in electron scattering have extracted an abnormally thick neutron skin for 208 Pb,which has significant consequences in nuclear equation of state(EoS)and neutron star *** this study,we perform optimizations of extended Skyrme forces in a consistent manner by including neutron skin thicknesses from PREX-Ⅱand CREX experiments and investigate nuclear EoSs and neutron stars in the GW170817 event By varying the fitting weights of neutron skins,several new Skyrme parameterizations are *** results show the competition in the fitting procedure to simultaneously describe neutron skins,other properties of finite nuclei,and neutron star *** prospects of resolving neutron skin issues are also discussed.

关键词： neutron skin equation of state neutron star Skyrme force

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Unbound^(28)O,the heaviest oxygen isotope observed:a cutting-edge probe for testing nuclear models

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nuclear Science and Techniques 2024年第2期35卷 1-2页

作者： Jian-Guo Li Bai-Shan Hu Shuang Zhang Fu-Rong Xu School of physics and State Key Laboratory of Nuclear Physics and TechnologyPeking UniversityBeijing 100871China institute of Modern physics Chinese Academy of SciencesLanzhou 730000China Southern Center for nuclear-Science Theory(SCNT) Institute of Modern PhysicsChinese Academy of SciencesHuizhou 516000China

The beyond-dripline oxygen isotopes^(27,28)O were recently observed at RIKEN,and were found to be unbound decaying into^(24)O by emitting *** unbound feature of the heaviest oxygen isotope,^(28)O,provides an excellent test for stateof-the-art nuclear *** atomic nucleus is a self-organized quantum manybody system comprising specific numbers of protons Z and neutrons N.

关键词： testing quantum system

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Possibilities for the synthesis of superheavy element Z=121 in fusion reactions

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nuclear Science and Techniques 2024年第6期35卷 90-100页

作者： Ming-Hao Zhang Yu-Hai Zhang Ying Zou Xiu-Xiu Yang Gen Zhang Feng-Shou Zhang The key laboratory of Beam technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China institute of Radiation technology Beijing Academy of Science and TechnologyBeijing 100875China School of Physical Science and technology Guangxi UniversityNanning 530004China National laboratory of heavy ion Accelerator of Lanzhou Center of Theoretical Nuclear PhysicsLanzhou 730000China

Based on the dinuclear system model,the calculated evaporation residue cross sections matched well with the current experimental *** synthesis of superheavy elements Z=121 was systematically studied through combinations of stable projectiles with Z=21-30 and targets with half-lives exceeding 50 *** influence of mass asymmetry and isotopic dependence on the projectile and target nuclei was investigated in *** reactions^(254)Es(^(46)Ti,3n)^(297)121 and^(252)Es(^(46)Ti,3n)^(295)121 were found to be experimentally feasible for synthesizing superheavy element Z=121,with maximal evaporation residue cross sections of 6.619 and 4.123 fb at 219.9 and 223.9 MeV,respectively.

关键词： Superheavy nuclei Dinuclear system model Fusion reaction Evaporation residue cross section

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