重离子反应中质子与中子转移对超重元素合成的影响

研究了采用类弹碎片质量数为变量的一维(1D)主方程(ME)描述重离子熔合反应时的受限制条件, 建立了以类弹碎片中子和质子数为独立变量的二维(2D) ME, 并采用分步差分格式法数值解(2D) ME得到了熔合几率。 新的方法适用于研究任何弹靶组合系统, 给出了与实验符合更好的结果, 为寻求合成超重核的反应道提供了更为宽阔的选择空间。 同时也研究了弹靶的不同同位旋组合对复合核形成截面的影响。 The limitation of the one dimensional master equation with the mass number of project like fragment as the variable is discussed. A two dimensional master equation with neutron and proton numbers of the project like fragment as variables is set up, and solved numerically by means of a two step difference scheme to obtain fusion probability. The new equation is suitable for studying fusion reactions with any projectile target combination, and can better fit the experimental data, so that it can provide a large probability to choose the reaction system for synthesizing a certain superheavy nucleus. The influence of projectile target combinations with different isospins on the cross sections of compound nuclei is studied.     

超重核密度的计算

用Skyrme Hartree Fock模型计算了超重核的密度分布,并讨论了其形状和同位旋相关性。 以292120核为例,计算表明形变对密度分布有相当大的影响。     

Systematic studies on α-decay half-lives for super heavy nuclei

Radioactive decay of super heavy nuclei via the emission of α-particles has been studied theoretically in the preformed cluster model （PCM）. The nucleus-nucleus （NN） potential is obtained by double folding the density distributions of the α-particle and the daughter nucleus with a realistic effective interaction. The M3Y effective interaction, supplemented by a zero-range pseudo-potential for exchange term, is used to calculate the NN potential. The α decay half-lives for 317 nuclei at Z=102 120 are performed in the PCM framework with the theoretical Q values extracted from the MSller-Nix-Kratz and Liran-Marinov-Zeldes mass tables and are compared with the experimental data. The calculated results are also compared with those obtained by using Q values from the Muntian-Hofmann-Patyk-Sobiczewski and Myers-Swiatecki mass estimates.     

自制三种物理实验装置及演示

1演示超重现象取透明塑料瓶一个,截去瓶底,并改用一张白纸封住底部（可用细线捆扎）．再取一段橡皮筋,一端和一柱形金属重物连结,并将重物放入瓶中,橡皮筋另一端固定在瓶口处．静止时重物不和白纸接触,约保持1cm距离．整个装置如图1所示．     

利用有效液滴模型对超重元素α衰变半衰期的研究

利用有效液滴模型计算了偶偶超重核的α衰变半衰期,计算过程中采用了保持碎片体积守恒的不对称形状描述以及有效惯性系数计算Gamow势垒穿透因子.首先在质子数Z为88—98的区域检验了有效液滴模型,发现计算结果与实验符合得比较好.随后将此模型推广到Z≥100的情况,虽然只用了两个模型参数,计算结果与实验数据符合,说明有效液滴模型是计算偶偶超重核素α衰变半衰期的一个成功模型.     

Optimal reactions for synthesis of nuclides of element 108

The cross sections for the production of nuclides of element 108 via hot fusion evaporation reactions are studied using a two-parameter Smoluchowski equation. The optimal reactions for the synthesis of new nuclides of element 108 with mass numbers from 266 to 271 are suggested. The macroscopic-microscopic approach predicts a strong deformed shell closure at Z \approx 108 and N=162. The synthesis of more nuclides of element 108 is meaningful to the confirmation of the existence of this deformed shell closure.     

热熔合反应合成超重核产生截面的同位素依赖性

通过在形成超重核的重离子俘获和熔合过程中引入位垒分布函数的方法对双核模型做了进一步发展. 超重核形成过程中的俘获、熔合和蒸发3个阶段分别采用了半经验的耦合道模型、数值求解主方程和统计蒸发模型的方法来描述. 计算了近年来Dubna小组利用热熔合反应⁴⁸Ca(²⁴³Am, 3n—5n)^288—286115和⁴⁸Ca(²⁴⁸Cm, 3n—5n)^293—291116合成超重新核素的蒸发余核激发函数. 系统分析了⁴⁸Ca轰击锕系元素U,Np,Pu,Am,Cm合成超重核Z=112—116产生截面的同位素依赖性. 给出了合成超重新核素最佳的弹靶组合和入射能量, 即有最大的超重核产生截面. 计算说明, 壳修正能和中子分离能是影响超重核生成截面产生同位素依赖性的主要因素.     

对超重和失重演示实验的改进

用U形压强计改进超重和失重演示实验,提高了演示的可见度和对比度     

Estimating Magic Numbers Larger Than 126 by Fermi—Yang Liming Method

The Fermi-Yang Liming method is followed and developed to estimate new magic numbers in nuclei with a Woods-Saxon density function.The calculated results predict that the magic number next to 126 should be around 184 and 258.     

超重核294118及其α衰变链的基态性质

用形变约束的相对论平均场理论系统研究了超重核²⁹⁴118及其α衰变链的基态性质, 给出了这些原子核的每核子结合能和α衰变能以及基态形变, 并与实验结果进行了比较, 发现理论计算和实验结果符合得很好, 表明相对论平均场理论对超重核基态性质的描述是合理有效的.