从CsCl靶中分离I、Ba和Ce的化学流程

用47MeV/nucleon的12C离子轰击133Cs靶,产生许多种不同元素的同位素。利用经典的化学分离方法,从大量的Cs和其它反应产物混合物中分离出I、Ba和Ce等。使用离线γ谱学方法,完成I、Ba、Ce等样品的γ活性测量。根据每种元素不同同位素的特征γ射线峰的强度和丰度,对I、Ba和Ce等样品中杂质的含量进行分析。结果显示该流程对杂质元素去污的效果是满意的。

~(139)Ce的多准粒子激发态

利用能量为50MeV的12C束流,通过反应130Te(12C,3n)布居了139Ce的高自旋态．基于标准在束核谱学实验测量结果,扩展并更新了139Ce的能级纲图．139Ce的能级结构具有球形原子核的典型特征,其高自旋态由单粒子激发形成．利用经验壳模型计算了139Ce的多准粒子激发态能量,研究了其高自旋激发态的多准粒子特性．

短寿命缺中子同位素~(130,129,128)Ce的(EC+β~+)衰变

首次报道130Ce、129Ce和128Ce的(EC+β+)衰变纲图,其中包括核素的产生、核素的分离鉴别以及纲图的建立。着重补充了一些重要的技术细节,更新了129Ce的衰变纲图,并对这些纲图中涉及的物理问题进行了讨论。

基于Windows CE的HIRFL-CSR前端控制系统设计与实现

介绍了一个基于WindowsCE的嵌入式分布控制系统,系统基于以太网和现场总线连接,节点用嵌入式平板计算机实现。给出了系统的硬件组成和软件设计,该系统已应用于HIRFL-CSR前端控制系统。

~(142)Ce的新激发态及其经验壳模型研究

利用 42 0MeV　82 Se轰击1 39La引起的深部非弹反应和在束γ谱学方法研究了1 4 2 Ce的中高自旋激发态 .识别出了激发能为 2 62 5,2 995和 3 83 4keV的 3个新能级 ,自旋、宇称分别被指定为 8+,9(- ) 和 1 1 (- ) .发现这些能级非常好地符合N=84偶偶核转晕能级的系统性 .利用经验壳模型计算了1 4 2 Ce的中高自旋激发态的激发能 ,计算结果比较好地重现了实验值 .对它们的结构进行了讨论 ,表明在1 4 2 Ce的中高自旋激发态中以单粒子激发为主

~(130)Ce(EC+β~+)衰变研究及其放射化学分离

利用兰州SFC加速的16O束轰击同位素118Sn ,由熔合蒸发 4n反应产生目标核13 0 Ce。为了消除本底干扰并指定13 0 Ce核 ,采用溶剂萃取法对He - jet带传输系统从靶室传输出来的反应产物进行了离线分离与纯化。将目标核13 0 Ce从大量的靶材料、反应产物及母核中分离出来 ,快速制成薄源后在铅室中进行γ单谱测量及X -γ、γ -γ符合测量。从化学分离后的产物中观察到了半衰期为 2 2 .9min的 10 8条γ射线 ,其中 10 7条是新发现的 ,该活性被指定为13 0 Ce。在此基础上 ,进一步研究这些γ线的级联关系 ,建立了缺中子同位素13 0 Ce较完整的 (EC + β+ )衰变纲图。为118Sn(16O ,4n) 13 0 Ce反应体系建立的放化分离流程的分离时间仅 10min ,化学产额大于70 %。化学分离除去 98%以上的核反应生成的13 0 La ,对其它杂质的去污完全满足13 0 Ce(EC + β+ )衰变研究的要求。

缺中子核素~(129)Ce的(EC/β~+)衰变

利用 10 2MeV16O6+束轰击同位素靶117Sn ,通过熔合蒸发 4n反应产生核素12 9Ce.由氦喷嘴快速带传输系统将反应产物送到低本底区 .通过化学分离来制备待测的Ce样品 ,与此同时用16O束轰击117Sn的两种相邻的同位素靶118Sn和116Sn ,并比较上述 3种反应中的产物来进一步区分元素Ce的不同的同位素 .结果一种半衰期为 4.1min的活性被鉴定为12 9Ce.基于X -γ -t和γ -γ -t符合测量 ,建议了包括 5 1条射线在内的12 9Ce的 (EC/ β+)衰变纲图 .其中 ,12 9Ce基态直接馈送到12 9La基态的份额 ( 2 6± 7) %是用观测到的12 9La衰变的 2 78.6keV的γ射线的生长和衰变曲线估计出来的 .另外还给出了用La Kα X射线和6 8.2keVγ射线开门的γ谱以及典型的衰变γ射线的时间谱

Multi-quasiparticle gamma-band structure in neutron-deficient Ce and Nd isotopes

The newly developed multi-quasiparticle triaxial projected shell model approach is employed to study the high-spin band structures in neutron-deficient even-even Ce- and Nd-isotopes. It is observed that gamma-bands are built on each intrinsic configuration of the triaxial mean-field deformation. Due to the fact that a triaxial configuration is a superposition of several K-states, the projection from these states results in several low-lying bands originating from the same intrinsic configuration. This generalizes the well-known concept of the surface gamma-oscillation in deformed nuclei based on the ground-state to gamma-bands built on multi-quasiparticle configurations. This new feature provides an alternative explanation on the observation of two I = 10 aligning states in Ce-134 and both exhibiting a neutron character. (C) 2009 Elsevier B.V. All rights reserved.

Study of multi-quasiparticle excited states in Ce-139

High-spin states in Ce-139 have been populated using the Te-130(C-12, 3n) reaction at beam energy of 50MeV. The level scheme of Ce-139 has been revised and extended greatly up to E=5765.0keV. The level structure of Ce-139 shows typical characteristics of spherical nucleus, and the high-spin states were formed by the excitations of valence nucleons. Energies of the yrast and near yrast high-spin states in Ce-139 have been calculated by the empirical shell model, and the multi-quasiparticle nature of high-spin excited states has been discussed.

Anomaly in the charge radii and nuclear structure

The axially deformed relativistic mean field theory is applied to study the isotope shift of charge distributions of odd-Z Pr isotope chain. The nuclear structure associated with the shell and the isotope effect is investigated. The mechanism of link in the isotope shift at the neutron magic number N = 82 is revealed to be dependent on the neutron energy level structure at the Fermi energy, demonstrating that the spin-orbit coupling interaction and p-n attraction are well described by the relativistic mean field theory.

Effects of rare earth on the structure and properties of Mg–6Zn–5Al–4Gd–1RE (RE = Ce or Y) alloys

The microstructures and mechanical properties of Mg-6Zn-5Al-4Gd-1RE (RE = Ce or Y) alloys were investigated. The addition of Ce or Y obviously refines the grain size for the Mg-6Zn-5Al-4Gd-based alloy, while the Y element has a better refining effect. The Ce and Y show different grain-refining mechanisms: Ce addition mostly promotes the growth of secondary dendrite, while Y addition mainly increases the heterogeneous nucleation sites.