ICP-MS分析四城市血铅浓度及同位素指纹地区特征

通过电感耦合等离子体质谱(ICP-MS)对北京、太原、苏州、成都四城市40份成人血铅进行了浓度及其同位素比值的同时测定,以考查不同地区血铅的地区性特征。结果显示工业城市成都、太原血铅浓度高于非工业城市北京、苏州,说明工业污染仍是造成高血铅的重要因素;同位素测试结果显示各城市血铅同位素比值具有特征分布区域和分布特点,食源性铅可能已取代大气铅成为北京等发达城市血铅的主要来源,全球化带来的的物产多样化削弱了一些发达城市铅污染的地区特征。     

间接标记假尿嘧啶核苷方法的研究

本文报告了固相标记假尿嘧啶核方法。用苯乙酸作偶联剂，以巯基树脂为载体，利用硫与汞的高效率结合，对假尿嘧啶核苷进行间接标准（I^125)。最后采用高压液相色谱分离，标记率为40-50%.     

Isotopic Trends of Fusion Probability in Reactions with Zn Isotopes Bombarding ^208Pb

where σc is the effective capture cross section for the transition of the colliding nuclei over the entrance Coulomob arrier, Wsur is the survival probability of the compound nucleus. In the DNS model, the compound nucleus is reached by a series of transfers of nuclcons from the light nucleus to the heavy one. Thc dynamics of the DNS is considered as a diffusion process in the mass asymmetry degree of freedom η=(A1 - A2)/(A1 A2) (A1 and A2 are the mass numbers of the DNS nuclei), PCN is the complete fusion probability, here it is calculated by solving the Master equation numcrically[2]. The fusion barrier Bfus in η supplies a hindrance for fusion.     

断前粒子发射的同位素效应

用推广的裂变扩散模型研究了²⁸Si+^164,167,170Er→^192,195,198Pb反应中测量的断前中子、质子和α粒子多重性的激发函数.发现扩散模型能很好地拟合这些轻粒子多重性随裂变系统激发能和Pb同位素的变化趋势.表明断前粒子发射存在一个同位素效应.进而在一个考虑了裂变过程中摩擦效应的统计模型的框架内,在In和Er这两个元素的同位素链中,考察了同位素效应与裂变碎片质量不对称性和裂变系统尺度的关系.计算结果表明:同位素效应的存在不依赖于裂变系统的大小和不对称性.此外,当裂变系统具有高的中质比时,轻带电粒子发射将不再敏感于裂变延迟时间的长短,而中子发射则非常敏感.这个结果暗示对那些特别丰中子的裂变系统,轻带电粒子(质子和α粒子)的多重性对于研究热核裂变过程中的摩擦强度不是一个好的探针.     

Ground-State Properties of Ca Isotopes and the Density Dependence of the Symmetry Energy

A relativistic mean field model is used to study the ground-state properties of neutron-rich nuclei in Ca isotopes. An additional isoscalar and isovector nonlinear coupling has been introduced in the relativistic mean field model, which could soften the symmetry energy, while keep the agreement with the experimental data. The sensitivity of proton and neutron density distributions and single particle states in Ca isotopes to the additional isoscalarisovector nonlinear coupling term is investigated. We found that the binding energies, the density distributions of single particle levels are strongly correlated with the density dependence of the symmetric energy in nuclear matter.     

利用快分子离子与固体的相互作用对H2+,HD+和D+2结构的研究

利用快分子离子与固体的相互作用,依靠一套高分辨装置,测量了H2+,HD+和D2+的结构,得到其核间距分别为1.19±0.003 nm、1.25±0.003 nm和1.32±0.003 nm.通过对比,证实了分子离子结构中同位素效应的存在,分析了实验值和理论值存在差别的原因,讨论了实验结果中同位素效应产生的缘由.     

氢同位素球形靶丸在其相应高能离子轰击下的消融

本文采用跨音速中性气体屏蔽模型,得到了氢同位素球形靶丸在其相应高能离子轰击下的消融率G_(is)及其定标律,s可为氢或氘。计算表明,当离子与电子的未扰态能量E_(0s)/E_(0e)~2≥1.5时,G_(is)/G_(es)≥20％,G_(es)为靶丸在等离子体电子轰击下的消融率。因此,当聚变实验有中性粒子束注入加热时,需考虑高能离子轰击对靶丸消融的影响。这也为此情况下靶丸消融强化提供了一种解释。     

Lifetimes of Excited Levels in ^131Ce

The fusion-evaporation reaction ^116Sn (^19F, p3n)^131 Ce at projectile energy of 95 MeV is used to populate high spin states in ^131Ce. The de-exciting γ-rays are detected in γ-γ coincidence measurement with Compton-suppressed BGO-HPGe detectors. Level lifetimes of ^131 Ce were determined by using the Doppler shift attenuation method.The experimental results indicate that collectivity of ^131 Ce is reduced relative to that of ^130Ce and it follows that deformation decreases with increase of the neutron number on the basis of systematic comparison of transition quadrupole moments for the light cerium isotopes.     

加速器质谱技术及其在测定36Cl中的应用

 加速器质谱技术（AMS）又称超灵敏质谱技术,是在80年代发展起来的一种超微量核分析方法。它对有些同位素分析的丰度灵敏度达到10（-16）,或者说可探测到10⁴个原子,比普通质谱计的灵敏度高出8-9个数量级。