209Fr的能级结构研究

利用能量为90—105MeV的¹⁶O束流,通过¹⁹⁷Au(¹⁶O,4n)反应研究了²⁰⁹Fr的高自旋态能级结构.进行了γ射线的激发函数、γ-γ延迟符合及γ射线的角分布测量.首次建立了由21条γ射线构成的²⁰⁹Fr的能级纲图,其中包括一个半寿命为(52±20)ns的同质异能态.基于²⁰⁹Fr与²⁰⁸Rn低位能级结构的相似性,用一个h_9/2价质子与²⁰⁸Rn激发态的弱耦合解释了²⁰⁹Fr的低位能级结构.     

缺中子核197Bi的能级结构研究

用100MeV¹⁶O束流轰击厚的天然Re靶和¹⁸⁷Re同位素靶,布居了¹⁹⁷Bi的高自旋激发态.用y-y-t符合测量,发现并修正了已有的¹⁹⁷Bi能级纲图中的错误,确定了¹⁹⁷Bi的三个新的高自旋同质异能态,识别出了11条新γ跃迁.并从奇A Bi核能级结构的系统性,对本工作确定的半寿命t_1/2=19.3±4.9ns的同质异能态的组态和衰变性质进行了探讨.本工作还测量了γ跃迁的角分布,建议了¹⁹⁷Bi的新的能级纲图.     

134Ba核的高激发态能级结构研究

在中国原子能科学研究院H-13串列加速器上, 通过重离子核反应¹³⁰Te(⁹Be,5n)与在束γ谱的实验技术, 对A=130缺中子核区的¹³⁴Ba核的高自旋态进行了研究, 建立了¹³⁴Ba核的新的能级纲图, 最高自旋态扩展到20h. 除验证了以前报道的大部分能级与跃迁外, 将基带的能级扩展到10⁺, 同时发现了基于10⁺同质异能态以上的众多的能级与跃迁. 对实验结果的系统学分析表明, 10⁺同质异能态为yrast陷阱, 起源于两中子组态, 可能具有γ≈－120°的长椭形状, 在其以上的能级表现出很强的单粒子性,具有复杂的结构. 基带中观测到明显的集体回弯现象, 推转壳模型的计算表明, 此集体回弯是由一对中子的顺排所致, TRS计算表明, 随着转动频率的增加, 核的形状发生明显的变化, 基带中在中子顺排后核具有γ≈－60°的扁椭形状.     

198Bi的高自旋态结构研究

利用能量为85—105MeV的¹⁶O束流,通过¹⁸⁷Re(¹⁶O,5n)反应研究了¹⁹⁸Bi的高自旋态能级结构.用6台BGO(AC)HPGe探测器和一台用于探测低能γ跃迁的平面探测器进行了γ射线的激发函数、γ-γ—t符合及γ射线的角分布测量.基于这些测量,首次建立了包括26条γ跃迁的¹⁹⁸Bi的高自旋能级纲图,确定了一个半寿命为(8.0±3.6)ns,自旋和宇称为15+的同质异能态.基于较重的双奇铋核^200—206Bi能级结构的系统性,定性地对¹⁹⁸Bi的能级结构进行了解释.     

136Ba的10+同质异能态

利用450MeV的⁸²Se束流轰击¹³⁹La靶,通过核子转移反应产生了¹³⁶Ba,用在束γ谱学方法测量了其激发态的γ衰变,观测到了它的10⁺态同质异能态并得到该同质异能态的寿命为94ns.     

143Nd中高自旋同质异能态的识别与研究

利用能量为80MeV的18O束流,通过¹³⁰Te(¹⁸O,5n)反应研究了¹⁴³Nd的高自旋态能级结构.基于γγ延迟符合、γ射线的角分布及线性极化测量,首次发现了¹⁴³Nd的一个半寿命为(35±8)ns,自旋和宇称为49/2⁺的同质异能态.用形变独立粒子模型探讨了此同质异能态的形成机制.     

^143Pm高自旋态研究

通过熔合蒸发反应^129Te(^19F,4nγ）布居了^143Pm的高自旋态,利用在束γ谱学方法,对^143Pm的高自旋态核结构进行了研究,测量了γ射线单谱和γ－γ符合谱,并进行了γ射线各向异性以及DCO比率分析,建立了激发高能达10535．4keV的能级纲图,其中包括新发现的32条γ射线和17个新能级,用弱耦合模型对^143Pm的晕态能级结构进行了解释。     

2．44-2．6MeV^178Hf核高激发态能级及性质

Coliins低能诱导6179Hfm^m2辐射衰变“正”面实验结果受到质疑的原因之一是未能确定出诱导实验的中间激发态。^178Hf核能级结构的实验数据表明：距同质异能态^178Hf^m2（2．446Mev）最近的一条能级是2．573MeV（K^π=14^＋）。因此，详细计算^178Hf核2．44-2．6MeV范围内高自旋、高激发核能级结构，对寻找低能诱导^178Hf^m辐射衰变中间激发态，分析低能诱发辐射实验可行性非常必要。     

奇—奇核~（114）Pm高自旋同质异能态及其衰变纲图的研究

用高自旋同质异能态次级束流线实验装置，对１４４Ｐｍ的高自旋同质异能态进行了快速分离，并做了γ射线的符合测量．结合γ射线激发函数和各向异性的测量结果，首次建立了奇—奇核１４４Ｐｍ的高自旋同质异能态的衰变纲图，其中１９条高自旋能级和２９条γ射线是由本工作指定的．离子γ射线关联测量确定了１４４Ｐｍ的高自旋同质异能态的半衰期大于２μｓ．通过系统性比较以及变形的独立粒子模型理论计算，指定了高自旋同质异能态的粒子组态可能为，自旋宇称为，并具有形变参数为β＝－０．１８的扁椭球形状．     

Reanalysis of Elastic Scattering of ~6Li + ~(209)Bi Reaction Using a New DensityDistribution of ~6Li Nucleus

In the present paper, the elastic scattering of6 Li + 209 Bi system is reanalyzed by using the double folding model (DFM) at energies near the Coulomb barrier (ELab=29.9 and 32.8 MeV). With this goal, a new density distribution of6 Li nucleus, the no-core full configuration (NCFC) density distribution (DD), is used to obtain the real potentials in DFM calculations. The NCFC DD results are compared with the results of both gaussian shape (GS) DD and an earlier study as well as the experimental data. This comparison provides information about the similarities and differences of the models used in calculations.     

12~(th) National Conference on Nuclear Structure and the 8~(th) Symposium on Nuclear Structure

The 12th National Conference on Nuclear Structure and the 8th Symposium on Nuclear Structure, hosted by Southwest University and organized by the Nuclear Structure Committee of the Chinese Nuclear Physics Society, China Center of Advanced     

A simple description of the temperature dependence of the width of the fission-fragment mass yield in ~(197)Au and ~(209)Bi at intermediate energies

A simple approach is proposed to describe the experimental data for the widths of the fission-fragment mass yields in~(197)Au and~(209)Bi at low and intermediate energies.The approach is based on the expressions for the temperature dependence of the width of the fission-fragment mass yield and the mass of the most probable fragment.The expression for the width of the fission-fragment mass yield depends on the mass of the most probable fragment,the surface terms of the energy level density parameter,the temperature and the stiffness parameter of the potential related to mass-asymmetric degree of freedom.It is shown that the contribution of the surface term of the energy level density parameter is important for describing the experimental data in a wide range of energies.     

Efect of Tensor Force on the Halo Structure of ~(29)Ne and ~(31)Ne

The structure of Ne isotopes has been investigated by using deformed Skyrme–Hartree–Fock(SHF)method and BCS approximation.Especially the efect of tensor force on the halo structure of 29Ne and 31Ne is discussed.To this end,the tensor contributions are considered to the energy density function and the single particle potential in SHF theory.For comparison,four Skyrme interactions are used:SLy5 and SGII without tensor force,and SLy5+T and SGII+T with tensor force.The results indicate that the inclusion of tensor force shows a more pronounced halo structure for31Ne.     

High-lying excited states in ~(10)Be from the ~9Be(~9Be,~(10)Be)~8Be reaction

A transfer-reaction experiment of ~9Be(~9Be,~(10)Be)~8Be was performed at a beam energy of 45 Me V.Excited states in ~(10)Be up to 18.80 Me V are produced using missing mass and invariant mass methods.Most of the observed high-lying resonant states,reconstructed from theα+~6He and t+~7Li decay channels,agree with the previously reported results.In addition,two new resonances at 15.6 and 18.8 Me V are identified from the present measurement.The 18.55 Me V state is found to decay into both the t + ~7Lig:s: and t + ~7Li?(0.478 MeV) channels, with a relative branching ratio of 0:93 ± 0:33. Further theoretical investigations are encouraged to interpret this new information on cluster structure in neutron-rich light nuclei.     

Langevin study of neutron emission in the reactions ^16O＋^181Ta and ^19F＋^178Hf^＊

The pre-scission neutrons measured in the reactions 16O 181Ta and 19F 178Hf are studied via a Langevin equation coupled with a statistical decay model. We find that because of the mass asymmetry of different entrance channels, the spin distributions of compound nuclei would be different, consequently, the measured neutrons in these two reactions would also different. This means that the entrance channel will affect the particle emission in the fission process of hot nuclei.     

Bremsstrahlung neutrino energy loss for ~(24)Mg,~(28)Si,~(32)S,~(40)Ca,~(56)Fe in strong electron screening

Based on Weinberg-Salam theory the bremsstrahlung neutrino energy loss for nuclei 24Mg,28Si,32S,40Ca and 56Fe are investigated in strong electron screening.Our results are compared with those of Dicus' and show that the latter are higher by 2 orders of magnitude in the density-temperature region of 108 g/cm3 ρ/μe 1011 g/cm3 and 2.5 T9 4.5.On the other hand,the factor C shows that the maximum differences are 99.16%,99.13%,99.12%,99.055%,99.040% corresponding to the nuclei 24Mg,28Si,32S,40Ca and 56Fe.     

Bremsstrahlung neutrino energy loss for ~(24)Mg, ~(28)Si, ~(32)S, ~(40)Ca, ~(56)Fe in strong electron screening

Based on WeinbergoSalam theory the bremsstrahlung neutrino energy loss for nuclei ~(24)Mg, ~(28)Si, ~(32)S, ~(40)Ca and ~(56)Fe are investigated in strong electron screening. Our results are compared with those of Dicus' and show that the latter are higher by 2 orders of magnitude in the density-temperature region of 10~8 g/cm~3 ≤ρ/μ_e≤10~(11) g/cm~3 and 2.5 ≤ T_9 ≤4.5. On the other hand, the factor C shows that the maximum differences are 99.16%, 99.13%, 99.12%, 99.055%, 99.040% corresponding to the nuclei ~(24)Mg, ~(28)Si, ~(32)S, ~(40)Ca and ~(56)Fe.