缺中子130Pm和128Pr核的EC/β+衰变研究

171MeV³⁶Ar束轰击⁹⁶Ru靶由熔合蒸发反应生成了¹³⁰Pm和¹²⁸Pr核.由氦喷嘴快速带传输系统将反应产物送到低本底区.基于X-γ-t,γ-γ-t符合测量,首次建立了¹³⁰Pm的(EC+β⁺)衰变纲图.重新研究了¹²⁸Pr核的衰变,订正和补充了γ射线,建立了新的(EC+β⁺)衰变纲图.     

快速电子辐照F-40的ESR和DSC研究

室温时空气中辐照F-40样品中残存有链侧和链端过氧化自由基,这些自由基在室温下衰变缓慢.DSC研究表明,F-40样品熔融温度T_m随辐照剂量的增加而下降,本文用聚合物片晶熔融的一般模型加以解释.     

70As(β++EC)衰变到70Ge的低自旋激发态(英文)

通过70As的放射性衰变研究了70Ge的激发态,新发现能量为1 036.99,1 196.66,1 539.29和2 531.7 keV的四条新γ射线,重新确认了2 219.34 keV γ射线的跃迁位置,新确认496.74,1 295.24和1 417.24 keV这三条γ射线首次放入衰变纲图,本工作证实了1 881.67,2 325.42和2 424.41 keV γ射线的跃迁位置,建议了能量为4 243.10和5 265.81 keV的两个新能级,建立了新的衰变纲图,基于比较半衰期和γ跃迁分支比建议了一些能级的自旋-宇称。The excited states of the 70Ge nucleus are investigated in radioactive decay of the 70As. Four new transitions with 1 036.99, 1 196.66, 1 539.29 and 2 531.7 keV are found for the first time. The position of 2 219.34 keV transition are reassigned, the transition positions of 496.74, 1 295.24 and 1 417.24 keV γ-rays are assigned for the first time, and the placements of 1 881.67, 2 325.42 and 2 424.41 keV γ-rays are confirmed in the present work. Two new levels, at 4 243.10 and 5 265.81 keV excitation energy, respectively, are proposed. The decay scheme is established and for a number of levels spin-parity assignments are suggested on the basis of logft values and γ-branching ratios.     

238U（9Be,5n）242Cm熔合蒸发反应激发函数测量（英文）

第一次测量到238U（9Be,5n）242Cm熔合蒸发反应的激发函数。通过使用叠层靶,在不改变束流能量的条件下,在线获得20个能量点下的实验数据。利用蒸发余核242Cm的半衰期较长,且衰变模式是α衰变的特点,用离线测量α放射性的方法得到目标核产额。实验最大截面约1 mb,激发函数曲线的形态和峰值所在的能量位置与现有的理论模型的计算结果一致。激发函数的实验数据对选择和优化理论模型,推动超铀核区核物理研究具有重要的意义。The excitation function of the 238U(9Be, 5n) reaction was obtained for the first time. By using a stack of uranium targets, 20 experimental data were obtained by the on-line irradiation without changing beam energy. Taking the advantage of the long lifetime and α decay mode of the residue nucleus 242Cm, the off-line measurement of the α radioactive was performed to obtain its yields. The maximum cross section is about 1 mb. The curve's shape and the maximum's position agree with the present model. The value of the cross section will help us to develop the ralated models, and push the nuclear studies in the transuranium region.     

Momentum transfer dependence behaviors of ionization and dissociation of oxygen

The decay pathways of the structured ionization region of oxygen at different momentum transfers,i.e.,0,0.23 a.u.(atomic unit),and 0.91 a.u.,are studied by measuring the ion and the scattered electron coincidently.It is found that the dipole-forbidden superexcited states of(2σu)-1(c4Σu-)npσu 3Σg-← X3Σg-decay into different channels according to the principal quantum number n.The broad ridge above 35 eV,which may be due to inner-valence excited states of(2σg)-1nλ or multiply excited states,is observed both at small and large momentum transfers,and its decay channel of O++ O is dominant.     

Tenua程序应用于放射性衰变的计算

借助Tenua动力学模拟程序,探讨了放射性衰变模拟计算在放射化学课程中的应用。对于连续衰变、分支衰变以及复杂的放射性衰变系,建立了相应的活度计算模型。模拟计算增加了计算结果的表现形式,促进了学生对所学知识的理解与掌握,丰富了现代教学方法。     

人工色荷电PG玻色子对B介子衰变中η′单举产率的增强

计算了人工色荷电PG玻色子π     

一般边界条件下球形压力容器钢壁中氚和氦-3的浓度变化规律研究

为了认识储氚高压容器壁材料的力学性能变化及其导致的容器承载能力变化, 必须研究储氚期间, 容器壁中氚和氦-3浓度的空间分布和随时间的变化. 针对容器外表面为一般传质边界条件和容器内部氚为范德瓦尔斯气体的情况, 同时考虑容器腔内和容器壁中氚的衰变和扩散, 建立求解储氚高压容器壁中氚和氦-3浓度的解析理论模型, 导出了氚和氦-3浓度的理论公式. 通过解析计算给出了器壁中氚和氦-3浓度随外表面传质系数的变化曲线和浓度的时空变化曲线, 提出了氦-3浓度的2β ₁ + β ₂ / 2倍定律, 即处于开放空间的储氚球形高压容器, 器壁中氦-3的浓度呈内高外低的分布, 时间越长, 浓度沿径向的梯度越大, 在时间足够长时, 各处浓度逼近时间无限长时的最终值, 也就是各处的最大值, 内表面处的最大值是该处氚初始时刻浓度的2β ₁ + β ₂ / 2倍, 这里β ₁ 和β ₂ 为与氚的范德瓦尔斯常数相关的参数. 研究结果为储氚高压容器的强度安全性评估提供了前提.     

PC Farms for Triggering and Online Reconstruction at HERA—B

The HERA-B data acquisition and triggering systems make use of Linux PC farms for triggering and online event reconstruction.We present in this paper the requirements,implementation and performance of both PC farms.They have been fully working during the year 2000 detector and trigger commissioning run.     

J/ψ→V1+X,X→γ+V2中玻色共振态X的自旋和宇称的确定

给出了过程J/ψ→V₁+X,X→γ+V₂,V₂→2P或3P(V₁和V₂代表矢量介子,P代表赝标价介子)的角分布公式.从而可以区分玻色共振态X的自旋,并在一定条件下确定它的空间宇称.