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

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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

Two-dimensional investigation of characteristic parameters and their gradients for the self-generated electric and magnetic fields of laser-induced zirconium plasma

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Plasma Science and Technology 2024年第5期26卷 138-155页

作者： Tayyaba SAJID Shazia BASHIR Mahreen AKRAM Maira RAZZAQ Khaliq MAHMOOD Centre for Advanced Studies in physics Institute of PhysicsGovernment College University LahoreLahore 54000Pakistan Department of physics Institute of PhysicsGovernment College University LahoreLahore 54000Pakistan

Two-dimensional diagnosis of laser-induced zirconium(Zr)plasma has been experimentally performed using the time-of-flight method by employing Faraday cups in addition to electric and magnetic *** characteristic parameters of laser-induced Zr plasma have been evaluated as a function of different laser irradiances ranging from 4.5 to 11.7 GW cm-2 at different axial positions of 1–4 cm with a fixed radial distance of 2 cm.A well-supporting correlation between the plume parameters and the laser-plasma-produced spontaneous electric and magnetic(E and B)fields was *** measurements of the characteristic parameters and spontaneously induced fields were observed to have an increasing trend with the increasing laser ***,when increasing the spatial distance in both the axial and radial directions,the plasma parameters(electron/ion number density,temperature and kinetic energy)did not show either continuously increasing or decreasing trends due to various kinetic and dynamic processes during the spatial evolution of the ***,the E and B fields were observed to be always diffusing away from the *** radial component of electron number densities remained higher than the axial number density component,whereas the axial ion number density at all laser irradiances and axial distances remained higher than the radial ion number *** higher axial self-generated electric field(SGEF)values than radial SGEF values are correlated with the effective charge-separation mechanism of electrons and *** generation of a self-generated magnetic field is observed dominantly in the radial direction at increasing laser irradiance as compared to the axial one due to the deflection of fast-moving electrons and the persistence of two-electron temperature on the radial axis.

关键词： Faraday cup axial and radial expansion space-charge effect laser-induced zirconium plasma two-electron temperature distribution self-generated electric and magnetic fields

An improved bound on accelerated light dark matter

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Science China(physics,Mechanics & Astronomy) 2024年第2期67卷 105-118页

作者： Liangliang Su Lei Wu Bin Zhu Department of physics and institute of Theoretical physics Nanjing Normal UniversityNanjing 210023China School of physics Yantai UniversityYantai 264005China

Light(sub-GeV)dark matter has gained increasing interest in terms of direct *** dark matter is a promising candidate that can generate detectable nuclear recoil energy within the sub-GeV *** of the large kinetic energy,its interactions with the nucleus are predominantly governed by inelastic scattering,including quasi-elastic and deep inelastic *** this work,we calculated the inelastic effects in dark matter-Earth scattering mediated by a vector *** analysis revealed that the impact of inelastic scattering relies on the mediator mass and the kinetic energy spectrum of dark *** results exhibited considerable disparity:the upper bounds of the exclusion limit for the spin-independent cross-section between accelerated dark matter and nuclei via a heavy mediator differ by several tens of times when inelastic scattering is considered.

关键词： accelerated dark matter inelastic scattering direct detection experiment

Consistency between domain wall oscillation modes and spin wave modes in nanostrips

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Chinese physics B 2024年第6期33卷 511-516页

作者：董新伟吴振江 Department of physics and institute of Theoretical physics and Astrophysics Xiamen UniversityXiamen 361005China

Investigations on domain wall(DW) and spin wave(SW) modes in a series of nanostrips with different widths and thicknesses have been carried out using micromagnetic simulation. The simulation results show that the frequencies of SW modes and the corresponding DW modes are consistent with each other if they have the same node number along the width direction. This consistency is more pronounced in wide and thin nanostrips, favoring the DW motion driven by *** analysis of the moving behavior of a DW driven by SWs is also carried out. The average DW speed can reach a larger value of ~ 140 m/s under two different SW sources. We argue that this study is very meaningful for the potential application of DW motion driven by SWs.

关键词： micromagnetic simulation domain wall spin wave

Semi-hydro-equivalent design and performance extrapolation between 100 kJ-scale and NIF-scale indirect drive implosion

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Matter and Radiation at Extremes 2024年第1期9卷 25-34页

作者： Huasen Zhang Dongguo Kang Changshu Wu Liang Hao Hao Shen Shiyang Zou Shaoping Zhu Yongkun Ding Laboratory of Computational physics Institute of Applied Physics and Computational MathematicsBeijing 10088China institute of Applied physics and Computational Mathematics Beijing 10088China

Extrapolation of implosion performance between different laser energy scales is investigated for indirect drive through a semi-hydroequivalent *** radiation transport is non-hydro-equivalent,the peak radiation temperature of the hohlraum and the ablation velocity of the capsule ablator are not scale-invariant when the sizes of the hohlraum and the capsule are scale-varied.A semi-hydro-equivalent design method that keeps the implosion velocity V_(i),adiabat α_(F),and P_(L)/R_(hc)^(2) (where P_(L) is the laser power and R_(hc) is the hohlraum and capsule scale length)scale-invariant,is proposed to create hydrodynamically similar *** semi-hydro-equivalent design and the scaled implosion performance are investigated for the 100 kJ Laser Facility(100 kJ-scale)and the National Ignition Facility(NIF-scale)with about 2 MJ laser *** is found that the one-dimensional implosion performance is approximately hydro-equivalent when V_(i) and α_(F) are kept the *** to the non-hydro-equivalent radiation transport,the yield-over-clean without α-particle heating(YOC_(noα))is slightly lower at 100 kJ-scale than at NIF-scale for the same scaled radiation asymmetry or the same initial perturbation of the hydrodynamic *** overall scaled two-dimensional implosion performance is slightly lower at 100 *** general Lawson criterion factor scales asχ_(noα) ^(2D)∼S^(1.06±0.04)(where S is the scale-variation factor)for the semi-hydro-equivalent implosion design with a moderate YOC_(noα).Our study indicates that χ_(noα)≈0.379 is the minimum requirement for the 100 kJ-scale implosion to demonstrate the ability to achieve marginal ignition at NIF-scale.

关键词： performance transport slightly

Ghost imaging—its physics and application [Invited]

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Chinese Optics Letters 2024年第6期 82-107页

作者：史砚华 Department of physics University of Maryland

Since its first experimental demonstration, “ghost imaging” has attracted much attention, perhaps not only because of its interesting physics but also because of its attractive application. This review article discusses the physics and application of ghost imaging:(1) emphasizes the nonlocal two-photon interference nature of ghost imaging, including detailed analysis and calculations;(2) introduces three types of applications with unique advantages of ghost imaging, including a light detection and ranging device with imaging ability, namely, an Imaging Lidar or ILidar system; a turbulence-resistant, or turbulence-free, imaging technology; and a vibration-resistant X-ray microscope of high resolving *** article is prepared for a Special Issue of Chinese Optics Letters, intended for general audiences, especially young researchers and students who are interested in ghost imaging.

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First-principles study of structural and electronic properties of multiferroic oxide Mn_(3)TeO_(6) under high pressure

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Chinese physics B 2024年第7期33卷 448-454页

作者：潘小龙王豪柳雷陈向荣耿华运 College of physics Sichuan UniversityChengdu 610065China National Key Laboratory of Shock Wave and Detonation physics Institute of Fluid PhysicsChina Academy of Engineering PhysicsMianyang 621900China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China

Mn_(3)TeO_(6)(MTO) has been experimentally found to adopt a P2_(1)/In structure under high pressure,which exhibits a significantly smaller band gap compared to the atmospheric R3 *** this study,we systematically investigate the magnetism,structural phase transition,and electronic properties of MTO under high pressure through first-principles *** R3 and P2_(1)/n phases of MTO are antiferromagnetic at zero *** R3 phase transforms to the P2_(1)/n phase at 7.5 8 GPa,accompanied by a considerable volume collapse of about 6.47%.Employing the accurate method that combines DFT+U/and GW,the calculated band gap of R3 phase at zero pressure is very close to the experimental values,while that of the P2_(1)/n phase is significantly *** main reason for this difference is that the experimental study incorrectly used the Kubelka-Munk plot for the indirect band gap to obtain the band gap of the P2_(1)/n phase instead of the Kubelka-Munk plot for the direct band ***,our study reveals that the transition from the R3 phase to the P2_(1)/n phase is accompanied by a slight reduction in the band gap.

关键词： magnetism phase transition band gap high pressure

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

Quantum speedup and non-Markovianity of an atom in structured reservoirs:pseudomodes as a good description of environmental memory

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Communications in Theoretical physics 2024年第8期76卷 62-68页

作者： Maryam Hadipour Soroush Haseli Saeed Haddadi Faculty of physics Urmia University of Technology School of physics Institute for Research in Fundamental Sciences (IPM) Faculty of physics Semnan University

Following the recent paper(Teittinen et al 2019 New J. Phys. 21 123041), one can see that in general there is no simple relation between non-Markovianity and quantum speed limit. Here, we investigate the connection between quantum speed limit time and non-Markovianity of an atom in structured environments(reservoirs) whose dynamics is governed by an exact pseudomode master equation(Garraway 1997 Phys. Rev. A 55 2290). In particular, we find an inverse relation between them, which means that the non-Markovian feature of the quantum process leads to speedup of evolution. Thus, there is a link between quantum speedup and memory effects for specific cases of dynamical evolution. Our results might shed light on the relationship between the speedup of quantum evolution and the backflow of information from the environment to the system.

关键词： non-Markovianity pseudomode method quantum speed limit structured environments