在Ne22照射U238核反应中观察到反常截面的金同位素

在Ne²²轰击U²³⁸靶的核反应中,用放射化学方法分离出金的同位素,曾用X射线谱等几种方法对金同位素进行了鉴定,测得Au¹⁹⁹的截面约为5×10^-27cm²。如果按已发表工作U²³⁸(Ne²²,f)中的分布曲线外推,则本文所测得的Au¹⁹⁹截面数值比外推得到的约大三个数量级,同时在这核反应中截面为毫巴数量级的Au¹⁹⁹产生也不能由核子传递反应机构来解释。对这个反常现象,我们试图着作了几种可能的解释。     

Th~(232)与U~(238)中子俘获截面的计算

本文采用复合核机制,计算了裂变道开放前Th~(232),U~(238)中子俘获截面。探索了光学模型、辐射宽度、统计涨落因子等因素的影响。     

U238自发裂变瞬时中子数目几率分布

用载镉(Cd)液体闪烁探测器测量了U²³⁸自发裂变瞬时中子数目几率分布P_v。实验得出P_v分布的宽度为σ_v=0.90±0.09,比其他重偶-偶核(Pu,Cm,Cf和Fm)相应的宽度来得窄,同时测得v=1.96±0.05,与以前的结果在误差范围内一致。     

质子与He+,Li++高能碰撞过程中电子俘获截面的理论计算

用OBK近似和CDW近似计算了H⁺+He⁺和H⁺+Li⁺⁺碰撞过程中电子俘获到激发态的分截面与俘获到基态分截面的比值，结果发现用OBK近似给出的比值和用CDW方法所给出的相应比值在高能区符合得很好．由此提出了一种用于计算高能H⁺与任一类氢离子碰撞的电子俘获总截面及任一激发态分截面的方法 关键词：     

U235及Pu239裂变中子能谱的测量

利用核-3乳胶测量了热中子引起U²³⁵及Pu²³⁹裂变中子能谱。结果如下:(1)Pu²³⁹裂变中子能谱显著地较U²³⁵裂变中子能谱为硬。其平均能量分别为:E_Pu=1.989±0.024兆电子伏;E_{U=1.867±0.015兆电子伏。(2)在2-3兆电子伏区域,发现有一个曲折,表明可能存在着能谱上的某种“结构”现象。}     

高能反中微子在O16上的俘获截面

用V-A型等效费米弱作用哈密顿计算了反应v+O¹⁶→N¹⁶+l的截面,得到了总截面与入射反中微子能量之间的关系曲线。计算表明,当E_v=400MeV时,等效赝标量作用项使总截面减小23％。     

H+,He2+与Li原子碰撞中电子俘获总截面的程函近似计算

采用Li原子价电子的有效势对前置形式程函近似振幅公式进行了修正,提出有效势修正程函近似方法,并对H^＋和He²⁺与Li原子碰撞中的电子俘获总截面进行了计算,取得了与实验比较吻合的结果. 关键词：     

奇奇核的U(B)(6)×U(v)(12)×U(π)(4)动力学对称性

本文讨论奇奇核U^(B)(6)×U^(v)(12)×U^(π)(4)动力学对称性的SO(6)极限情形.除计算能谱外,对体系的波函数、E(2)电磁跃迁几率和单粒子转移反应强度都进行了计算,并得到相应精确解.最后就¹⁹⁸Au₁₁₉和¹⁸⁸Ir₁₁₁两核的实验能谱与理论计算值进行了比较并作了讨论.     

稀土离子Ho+,Ce+,La+与H2碰撞的单电子俘获截面测量

在复旦大学加速器实验室的３０ｋｅＶ同位素分离器上，使用新近建立的一套用于单价离子与气体分子碰撞的单电子俘获截面测量装置，测量了５—３０ｋｅＶ Ho⁺,Ce⁺,La⁺与H₂碰撞的单电子俘获截面．实验发现中空型离子源的阳极电压的变化对于稀土离子的亚稳态比例有一定影响，同时造成了单电子俘获截面的很大变化，而阳极电压对Ａｒ⁺的影响很小．还对实验结果进行了分析 关键词：     

MEASUREMENT OF THE FAST NEUTRON CAPTURE CROSS SECTIONS OF NATURAL NUCLEI Ta AND In

The neutron capture cross sections of Ta and In were measured in the energy range from 0.34 to 1.68MeV.A large liquid scintillator detector was used for detecting the prompt capture γ radiation.Two long-counters were used for monitoring the neutron flux.In order to reduce background the fast coincidence between the two half-spheres of the detector and the time-of-flight technique were used.The capture cross sections of Ta and In were determined relative to the standard cross section of Au.Present results were compared with others and discussed.     

MEASUREMENTS OF NEUTRON CAPTURE CROSS SECTIONS OF WOLFRAM AND GADOLINIUM BETWEEN 560 AND 1610keV

Neutron capture cross sections of W and Gd were measured relative to that of Au at six neutron energy values by using a large liquid scintillator tank and time-of-flight technique.The accelerator used was a 2.5MV pulsed van de Graff.The present results agree well with other recent measurement.     

类氦铷、铌离子光电离截面的细致计算

采用ＨＦ加相对论修正的ＨＦＲ方法，考虑束缚组态间的相互作用，计算了类氦铷与类氦铌离子各能级间跃迁的光电截面，所包括的离子组态为１ｓｎｌ—１ｓεｌ±１（１≤ｎ≤６、０≤ｌ≤ｎ－１），取自由电子能量区间为０～１０倍的离化能，分析了系统计算误差与计算精度，给出了对未态求和及三次样条插值后的结果。     

Z1- AND Z2-OSCILLATIONS OF ELECTRONIC STOPPING CROSS SECTIONS OBTAINED BY SHELL-WISE CALCULATION AND HARMONIC-OSCILLATOR MODEL

A shell-wise calculation method and a quantal harmonic-oscillator model have been used to calculate the electronic stopping cross sections for heavy ions colliding with atoms or penetrating matter. The electronic energy loss is given in an impact parameter formalism. In order to generalize the theoretical models, which pertain to the cese of point charge interacting with matter, to the case for heavy ions, an effective stopping charge hased on the modified BK theory is used by way of simple scaling in the calculations. The comparisons between the calculated results and the experimental data demonstrate a favourable evidence to justify the theoretical models.     

36Krq+(q=1,2)与H和He碰撞的电荷剥离截面

采用二体碰撞近似和托马斯-费密近似方法计算了多电荷离子₃₆Kr^q+的势函数和电子动量分布,以及它与中性原子H和He碰撞的电荷剥离截面. 关键词：     

电子氢原子碰撞电离能量微分截面和总截面的理论计算

利用扭曲波玻恩交换（ＤＷＢＥ）近似方法对电子－氢原子碰撞电离截面进行了计算，计算所得总截面和能量微分截面均与最新的实验结果进行了比较，比较结果显示本计算与实验有较好的符合。还给出了能量微分截面的高斯拟合公式，文中对实验与理论计算存在的一些差距进行了讨论。 关键词：     

INFLUENCE OF THE NEUTRON NUMBER OF TARGET NUCLEUS ON CROSS SECTIONS OF PARTICLES EMISSION IN 12C+112,124Sn

The energy spectra and angular distributions of Li, Be, B particles emitted from the ¹²C+¹¹²Sn and ¹²C+¹²⁴Sn reactions at E_L=70.0MeV are measured. The angular distributions of the Li, Be, and B particles are found to be peaked around the grazing angle, without any forward peaked component.
The experimental results also showed that the cross section for emission is larger in ¹²C+¹¹²Sn reaction than that in ¹²C+¹²⁴Sn reaction, in contrast with the cross sections for Li, Be and B emissions. The indicates the effect of the neutron number of the target nucleus on the emission probability.