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Science China(Physics,Mechanics & Astronomy) 2019年第4期62卷 57-64页

作者： HaoJie Xia XianYe Wu Hua Mei JiangMing Yao School of Mechanical and Electrical Engineering Handan University College of Physics and Communication Electronics Jiangxi Normal University Department of Physics and Astronomy University of North Carolina Chapel Hill Department of Physics Tohoku University FRIB/nscl Michigan State University

We develop both relativistic mean field and beyond approaches for hypernuclei with possible quadrupole-octupole deformation or pear-like shapes based on relativistic point-coupling energy density functionals. The symmetries broken in the mean-field states are recovered with parity, particle-number and angular momentum projections. We take_Λ^(21)Ne as an example to illustrate the method, where the Λ hyperon is put on one of the two lowest-energy orbits(labeled as Λ_s, Λ_p), respectively. We find that the Λ hyperon in both cases disfavors the formation of a reflection-asymmetric molecular-like^(16)O+α structure in^(20)Ne, which is consistent with the Nilsson diagram for the hyperon in(β_2, β_3) deformation plane. In particular, we show that the negative-parity states with the configuration^(20)Ne(K~π= 0^-)  Λ_s are close in energy to those with the configuration^(20)Ne(K~π= 0^+)Λ_p, even though they have very different structures. The Λ_s(Λ_p) becomes more and more concentrated around the bottom(top) of the"pear" with the increase of octupole deformation.

关键词： hypernucleus relativistic mean field octupole deformation cluster structure

一台14GHz CAPRICE型ECR离子源的束流引出(英文)

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Chinese Physics C 2007年第S1期31卷 192-195页

作者： P.Spdtke I J.Mder J.Roβbach K.Tinschert J.Stetson GSI DarmstadtGermany MSU-nscl MichiganUSA

An ion beam extracted from an ECRIS suffers from the inhomogeneous distribution of cold electrons within the minimum B configuration,necessary to confine the *** for higher ion currents,the space charge force is not negligible any more,and because of the nonlinear force,emittance growth will occur. Measurements of the profile and the emittance of the beam directly behind the source show the complicated correlation between extraction voltage and plasma *** emittance has been measured with a pepper pot device to account for the inhomogeneous azimuthal distribution of the *** results indicate that further information about the profile is *** visualize the beam profile a tantalum foil with a thickness of 20μm has been used for an electrical beam power between 10 and *** on the back side of the foil with a CCD camera it is possible to record the profile in real *** a more sensitive diagnostic tool viewing targets made from BaF has been used. Three dimensional computer simulations have been used to identify the reason for the structures,observed in measurements.

关键词： ECRIS extraction extraction simulation beam profile

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利用重离子碰撞确定对称能的密度依赖形式

原子核物理评论 2011年第4期28卷 377-395页

作者：张英逊卢晓华赵凯李祝霞 P．Danielewicz M．B．Tsang 中国原子能科学研究院核物理研究所北京102413 Michigan State University/nscl East Lansing MI 48824 USA

对称能的密度依赖形式对于中子星结构及其演化规律、不稳定核结构及其反应等都有非常重要的影响。由于目前理论上预言的对称能密度依赖形式有很大的不确定性,因此确定对称能的密度依赖形式已经成为目前核物理研究的一个重要课题。丰中... 详细信息

对称能的密度依赖形式对于中子星结构及其演化规律、不稳定核结构及其反应等都有非常重要的影响。由于目前理论上预言的对称能密度依赖形式有很大的不确定性,因此确定对称能的密度依赖形式已经成为目前核物理研究的一个重要课题。丰中子核重离子碰撞是目前在实验室条件下确定对称能密度依赖形式的一种重要手段,其主要的理论依据就是微观输运理论。首先回顾了目前输运理论的两个处理方法,即Boltzmann-Uehling-Uhlenbeck(BUU)和量子分子动力学(QMD)方法,并重点介绍了改进的量子分子动力学模型(ImQMD05)。利用ImQMD05对中能重离子碰撞的一些基本观测量,如碎块分布、集体流、核核碰撞的阻止本领等进行了详细研究,通过与实验数据的比较,确定了ImQMD05中同位旋无关部分的平均场、介质中核子-核子散射截面。为了从重离子碰撞的实验数据确定对称能的密度依赖形式,详细研究了输运理论中对称势以及同位旋相关的介质中核子-核子散射截面对于同位旋敏感观测量的影响。研究显示,对于Fermi能附近的重离子碰撞,输运理论预言的同位旋敏感的观测量,如DR(n/p)和Ri,强烈依赖于对称势的软硬,而不敏感于介质中同位旋相关的核子-核子散射截面。多重碎裂作为中能重离子碰撞的一个主要特点,本文论述的研究显示碎块发射机制对同位旋敏感的观测量,出射核子的双中子质子之比DR(n/p)和同位旋转移之比Ri,都有重要影响。以重碎块的同位旋不对称度为探针得到的同位旋转移之比Ri(δZmax>20)要大于Ri(δ),这些测量能够在nscl/RIKEN的相关实验上进行测量。同时,这一现象的研究对于理解碎块的发射机制及碎块发射的特征时间等问题将有重要的帮助。为此,采用ImQMD05研究了112,124Sn+112,124Sn在入射能量50MeV/u,不同碰撞参数条件下的多个实验观测量,如DR(n/p)、同位旋扩散Ri以及同位旋转移之比的快度分布。研究表明,模型能够同时自洽地解释这几个实验观测量,并通过与这些实验数据的分析比较,自洽地确定出低密区对称能密度依赖形式的范围。

关键词：对称能重离子碰撞集体流核核碰撞的阻止本领

Novel evidence for the σ-bond linear-chain molecular structure in ^(14)C

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Chinese Physics C 2021年第8期45卷 71-75页

作者：余翰舟李晶叶沿林杨彪林承键贾会明楼建玲杨晓菲 T.Baba 李奇特葛愉成李智焕华辉许金艳杨再宏冯俊臧宏亮刘强蒋伟刘洋李晶晶刘威白世伟陈洁韩家兴陈家豪马凯王东玺杨磊马南苑孙立杰 School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking UniversityBeijing 100871China FRIB/nscl Laboratory Michigan State UniversityEast LansingMichigan 48824USA China Institute of Atomic Energy Beijing 102413China Kitami Institute of Technology 090-8507 KitamiJapan Research Center for Nuclear Physics(RCNP) Osaka University10-1 MihogaokaIbarakiOsaka 567-0047Japan Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523803China

A multi-nucleon transfer and cluster decay experiment,^(7)Li(^(11)B,^(14)C^(*)→α+^(10)Be)α,is conducted at an incident beam energy of 55 *** reaction channel has a significantly large 0-value,which favors populating the high lying resonant states in ^(14)*** decay paths,from these resonances to various states of the final nucleus ^(10) Be,can be selected,owing to the experimentally achieved optimal resolution of the Q-value spectrum.A number of resonant states are reconstructed from the forward emitting 10Be+α fragments,and their major molecular structures can be detected according to the selective decay paths and relative decay widths.A state at 22.4(2)MeV validates the previously measured and theoretically predicted band head of the positive-parity σ-bond linear-chain mo-lecular *** additional resonances at 22.9(2)and 24.2(2)MeV are identified and consistent with the predicted 2^(+) and 4^(+) members of the same molecular band,thus providing novel evidences for the existence of the exotic clustering chain structure in neutron-rich carbon isotopes.A few high energy resonances,which also indicate the presence of the σ-bond molecular structure,are observed;however,further studies are still required to clarify their ascription in band systematics.

关键词： linear-chain state reaction 0-value transfer reaction cluster decay relative branching ratio