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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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Simulation of nuclear isomer production in laser-induced plasma

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Matter and Radiation at Extremes 2024年第5期9卷 1-9页

作者： Zhiguo Ma Yumiao Wang Yi Yang Youjing Wang Kai Zhao Yixin Li Changbo Fu Wanbing He Yugang Ma Key laboratory of nuclear physics and Ion-Beam Application(MoE) Institute of Modern PhysicsFudan UniversityShanghai 200433China

nuclear isomers play essential roles in various fields,including stellar nucleosynthesis,nuclear clocks,nuclear batteries,clean nuclear energy,and-ray *** technological advances in high-intensity lasers have made it possible to excite or de-excite nuclear isomers using table-top laser *** a particle-in-cell code,we investigate the interaction of a laser with a nanowire array and calculate the production rates of the^(73m)Ge(E_(1)=13.3 keV)and^(107m)Ag(E_(1)=93.1 keV)***^(73m1)Ge,production by Coulomb excitation is found to contribute a peak efficiency of 1.0×10^(19) particles s^(−1)J^(−1),while nuclear excitation by electron capture(NEEC)contributes a peak of 1.65×10^(11)particles s^(−1)J^(−1).These results indicate a high isomeric production ratio,as well as demonstrating the potential for confirming the existence of NEEC,a long-expected but so far experimentally unobserved fundamental process.

关键词： process. isomers excitation

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Relativistic configuration-interaction density functional theory:Nonaxial effects on nuclear ββ decay

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Science Bulletin 2024年第13期69卷 2017-2020页

作者： Yakun Wang Pengwei Zhao Jie Meng State Key laboratory of nuclear physics and Technology School of PhysicsPeking UniversityBeijing 100871China

nuclear ββ decay is a second-order weak process in which an even-even nucleus decays to its neighboring even-even nucleus by turning two neutrons to two protons while emitting two electrons.A nucleus undergoes such ... 详细信息

关键词： decay neighboring interaction

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Principal components of nuclear mass models

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Science China(physics,Mechanics & Astronomy) 2024年第7期67卷 65-71页

作者： Xin-Hui Wu Pengwei Zhao Department of physics Fuzhou UniversityFuzhou 350108China State Key laboratory of nuclear physics and Technology School of PhysicsPeking UniversityBeijing 100871China

Principal component analysis(PCA)is employed to extract the principal components(PCs)present in nuclear mass models for the first *** effects from different nuclear mass models are reintegrated and reorganized in the extracted *** PCs are recombined to build new mass models,which achieve better accuracy than the original theoretical mass *** comparison indicates that using the PCA approach,the effects contained in different mass models can be collaborated to improve nuclear mass predictions.

关键词： nuclear mass principal component analysis nuclear models statistical methods

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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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Electronic effects on radiation damage inα-iron:A molecular dynamics study

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Chinese physics B 2024年第3期33卷 521-529页

作者：江林李敏付宝勤崔节超侯氢 Key laboratory for Radiation physics and Technology Institute of Nuclear Science and TechnologySichuan UniversityChengdu 610064China

Iron(Fe)-based alloys,which have been widely used as structural materials in nuclear reactors,can significantly change their microstructure properties and macroscopic properties under high flux neutron irradiation during operation,thus,the problems associated with the safe operation of nuclear reactors have been put forward *** this work,a molecular dynamics simulation approach combined with electronic effects is developed for investigating the primary radiation damage process inα-***,the influence of electronic effects on the collision cascade in Fe is systematically evaluated based on two commonly used interatomic potentials for *** simulation results reveal that both electronic stopping(ES)and electron-phonon coupling(EPC)can contribute to the decrease of the number of defects in the thermal spike *** application of ES reduces the number of residual defects after the cascade evolution,whereas EPC has a reverse *** introduction of electronic effects promotes the formation of the dispersive subcascade:ES significantly changes the geometry of the damaged region in the thermal spike phase,whereas EPC mainly reduces the extent of the damaged ***,the incorporation of electronic effects effectively mitigates discrepancies in simulation outcomes when using different interatomic potentials.

关键词： radiation damage electronic effects molecular dynamics simulation α-iron

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Domain wall network:A dual solution for gravitational waves and Hubble tension?

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Science China(physics,Mechanics & Astronomy) 2024年第11期Mechanics & Astronomy) .卷 43-50页

作者： Ligong Bian Shuailiang Ge Changhong Li Jing Shu Junchao Zong Department of physics and Chongqing Key laboratory for Strongly Coupled physics Chongqing University Center for High Energy physics Peking University School of physics and State Key laboratory of nuclear physics and Technology Peking University Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan Province School of Physics and AstronomyYunnan University Beijing Laser Acceleration Innovation Center Department of physics Nanjing University CAS Key laboratory of Theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences

We explore the possibility that domain wall networks generate the stochastic gravitational wave background（SGWB） observed as a strong common power-law process in the Data Release-2 of Parkes Pulsar Timing Array. We find that a broad range of parameters, specifically wall tension around σDW～（29-414 TeV）3and wall-decay temperature within Td～ 20-257 MeV, can explain this phenomenon at a 68% credible level. Meanwhile, the same parameters could ease the Hubble tension if particles from these domain wall networks decay into dark radiation. We establish a direct analytical relationship, ?GW（fp, T0）h2～ ?radh2(?ν?Neff)2,to illustrate this coincidence, underlining its importance in the underlying physics and potential applicability to a wider range of models and data. Conversely, if the common power-law process is not attributed to domain wall networks, our findings impose tight limits on the wall tension and decay temperature.

关键词： domain wall gravitational waves Hubble tension

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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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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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