近代物理研究所超重核研究现状及计划

简单描述了超重核合成的历史与国际现状， 详细地介绍了近代物理研究所已经开展的研究工作及取得的成果， 并对近代物理研究所未来在超重核研究方面的研究计划进行了介绍。 The history and the international status of the super heavy nuclei synthesis are briefly described. The related research work carried out at the Institute of Modern Physics (IMP) has been reviewed. The prospect of the super heavy nuclei research at IMP has been introduced.     

超重核合成理论模型简介

介绍并讨论了研究超重核合成的主要理论模型以及近年来在研究重核熔合机制和超重核合成理论模型方面的进展。 The theoretical models for investigating the fusion mechanism of heavy nucleus collisions and calculating the formation cross sections of superheavy nuclei have been introduced. The recent development and the present status for understanding the fusion mechanism of heavy nucleus collisions have been discussed.     

重离子碰撞中超重核的形成机制(英文)

在双核模型框架下,用数值解主方程方法计算了超重核的熔合几率。 明确描述了包含能量、角动量和碎片形变弛豫的相对运动,并与核子扩散过程相耦合。因此,用微观方法推导出的核子跃迁几率是与时间相关的。所计算的以Pb为靶的冷熔合超重核形成截面和以48Ca为弹核的热熔合超重核形成激发函数与已知的实验值在合理的范围内符合。In the dinuclear system conception, the master equation is solved numerically to calculate the fusion probabilities of super heavy nuclei. The relative motion concerning the energy, the angular momentum and the fragment deformation relaxations is explicitly treated to couple with the diffusion process. The nucleon transition probabilities, which are derived microscopically, are related with the energy dissipation of the relative motion, thus they are time dependent. The formation cross sections of the super heavy nuclei from Pb based cold fusion and excitation functions from 48Ca induced hot fusion are reasonably consistent with known experimental data.     

推广的液滴模型及其应用

简单介绍了近年来在研究重核和超重核衰变性质及熔合反应方面取得的理论成果和面临的挑战,着重阐述推广的液滴模型(GLDM) 理论框架及其应用。基于原子核的质量数、质子数以及反应Q 值,GLDM考虑了质量和电荷的不对称性、形状演化、亲近势和温度等,很好地描述了重核和超重核的质子放射性、 衰变、重离子放射性、自发裂变的半衰期和重离子熔合反应截面,同时也研究了原子核的粒子(质子、 、重离子) 放射性与自发裂变的竞争。Recent theoretical achievements and challenges about the fusion and decay properties of heavy and superheavy nuclei are generally introduced. Especially, the Generalized Liquid Drop Model(GLDM) as well as its application are emphatically described. Based on the mass number, proton number and the reaction Q value, the GLDM has taken the mass and charge asymmetry, the shape evolution, the proximity potential, as well as the temperature of nucleus into account, well described the proton radioactivity, the decay, the heavy particle radioactivity, the half life of spontaneous fission of heavy nuclei and superheavy nuclei, and the cross-sections of heavy ion fusion. The competitions between the spontaneous fission and other decay modes such as proton and heavy particle radioactivity, the alpha decay, and so on are also studied.     

在超重核区应用Viola Seaborg公式研究α衰变寿

在超重核区（Z≥104）使用文献[7—9]给出的3组参数应用Viola Seaborg公式计算了α衰变寿命, 所得结果与实验值进行比较, 发现其结果与实验值相差较大。 为此, 利用最小二乘法分别在重核区和超重核区重新对参数进行了拟合, 得到的计算结果与实验值相比符合得较理想, 尤其是由超重核得到的参数的结果非常理想。The α decay half lives of the super heavy nuclei in the mass region （Z≥104） were calculated by Viola Seaborg formula with three sets of parameters. The calculated results show that all the three sets of parameters caused rather large deviations from the experimental data. To solve this problem, we have done a parameter fitting in the regions of heavy nuclei and super heavy nuclei respectively, with the least squares method. With the new sets of parameters, the calculated α decay half lives are in much better agreement with the experimental data. In particular, the results calculated with the new parameters in the region of super heavy nuclei are even better.     

重离子熔合反应与双核模型

简单介绍了兰州-北京-吉森合作组对合成超重核的重离子反应进行的初步研究。研究的重点是熔合阶段的反应机制。在原有双核模型的基础上做了一些改进,把耗散相对运动过程与核子转移过程耦合起来,从更微观的角度来描写双核系统向全熔合复合核的演化。在双核过程中的每一步求解主方程,不对驱动势做谐振子近似。同时,还探讨了原子核形变与相对取向对驱动势的影响,存活几率与复合核蒸发中子的奇偶效应,以及入射道中原子核非弹性激发对俘获截面的影响等。In recent years, the Lanzou-Beijing-Giessen collaboration has studied the heavy ion reactions which are lead to the formation of super-heavy nuclei. The study emphases the mechanism of the fusion stage of the reactions. Based on the so called Di-nuclear System Model, some improvements have been made. The main points are the coupling of the dissipation of relative motion energy, angular momentum with nucleon transfer, and solving the Master equation in every step of the nucleon transfer with exact driving potentials, in order to describe the evolution of the system more microscopically. At the same time, we also discussed the effects of nuclear deformation and their relative orientation on the driving potentials, and studied the survive probability of the compound nuclei and its old-even effects, as well as the influence of inelastic excitations of nuclei in entrance channels to the capture cross sections.     

HIRFL上的中、低能重离子物理基础和应用研究

本文简介HIRFL上中、低能重离子物理基础和应用研究的主要进展;着重介绍三个方面的研究:中能HIC和热核性质的研究,远离稳定线核的合成和研究,重离子束应用,并概述近期实验研究规划的初步建议。 The experimental studies and achievements recently made at the Heavy Ion ResearchFacility of Lanzhou(HIRFL) are reviewed with an emphasis on the three research fields: the study of intermediate energy heavy ion collision and properties of hot nuclei, the synthesis and study of nucleifar from stability, and the applications of heavy ions. A research program for the near future is alsobriefly introduced.     

重离子熔合反应形成超重核的截面研究

在双核系统框架下,通过数值法解主方程计算了双核间的核子跃迁全熔合几率.两碰撞核内部激发能由相对运动能损提供,因此能够将核子转移过程与相对运动耦合起来.对一些以Pb为靶的形成超重核的冷熔合反应,计算了最佳激发能、形成双核系统的俘获截面、复合核形成几率及存活几率等,所得到的形成超重核蒸发剩余截面与已知实验值符合较好. In the concept of Dinuclear system (DNS) the complete fusion probability of two touch nuclei via nucleon transfer is described by numerically solving the Master equation. The excitation energy of two colliding nuclei is supplied by the energy dissipation of their relative motion, thus the nucleon transfer process and the relative motion are coupled. For Pb based cold fusion reactions to form super heavy nuclei, the optimal excitation energy, the capture cross section to form a DNS ...     

超重核的生成和衰变

简单介绍了近年来在超重核研究方面所取得的成就和理论方面所面临的挑战.着重介绍推广的液滴模型和准分子形状机制,它们的优点是考虑了精确的核半经、质量和电荷的不对称性、形变、亲和力和温度等.推广的液滴模型和准分子形状机制能很好地描述重核和超重核的裂变、衰变及完全熔合反应.The progress and challenge on studies of superheavy elements both experiments and theories has been briefly introduced. It is emphasis to introduce a generalized liquid drop model, including the proximity effects, the asymmetry, an accurate nuclear radius, and quasi molecular shapes. The α decay half lives of 373 nuclei and superheavy elements have been calculated in the generalized liquid drop model and compared with the available experimental data. The deformed energies have also been obtained ...     

Isoscalar giant monopole resonance for drip-line and super heavy nuclei in the framework of relativistic mean field formalism with scaling calculation

We study the isoscalar giant monopole resonance for drip-lines and super heavy nuclei in the framework of relativistic mean field theory with a scaling approach. The well known extended Thomas-Fermi approximation in the nonlinear σ-ω model is used to estimate the giant monopole excitation energy for some selected light spherical nuclei starting from the region of proton to neutron drip-lines. The application is extended to the super heavy region for Z=114 and 120, which are predicted by several models as the next proton magic numbers beyond Z=82. We compared the excitation energy obtained by four successful force parameters NL1, NL3, NL3*, and FSUGold. The monopole energy decreases toward the proton and neutron drip-lines in an isotopic chain for lighter mass nuclei, in contrast to a monotonic decrease for super heavy isotopes. The maximum and minimum monopole excitation energies are obtained for nuclei with minimum and maximum isospin in an isotopic chain, respectively.     

靶用低密度聚4-甲基-1-戊烯泡沫的制备与表征

 通过控制体系的受热历史,改进了惯性约束聚变靶材料聚4-甲基-1-戊烯(TPX)泡沫二元溶剂体系的制备工艺,并利用β射线检测和X射线照相技术,对不同制备工艺的泡沫柱进行密度分布表征。结果表明：两种方法检测的结果基本一致,即凝胶过程的冷却速率为1 ℃/min,且凝胶后采用淬冷使其快速固化的方法能制得密度分布均匀的低密度TPX泡沫样品,从而确定了均匀泡沫的最佳制备工艺。由于二元溶剂体系的超低密度TPX泡沫样品孔径太大,极个别大孔可达数百μm,均匀度极低,所以采用TPX的环己烷一元溶剂体系可以成功制备出最低密度达3 mg/cm³的超低密度TPX泡沫样品,且满足Z箍缩物理实验用靶的需求。     

Systematic Study of Stability of Super Heavy Nuclei

A systematic overview on the characteristics of super heavy nuclei from Z = 101 to Z = 130 based on the data by P. Moller et al. is presented. The nuclei which have the biggest mean binding energy in each of their isotope chain show systematic regular behavior, indicating that the mean binding energy is a good criterion to classify super heavy nuclei by their stabilities. Further investigation on the nuclear data at and after Z=127 has been suggested.     

基于Weizsäcker-Skyrme核质量公式研究原子核基态性质

基于一个半经验的原子核宏观 微观质量公式——Weizsäcker-Skyrme质量公式, 研究了原子核的形变、 滴线、 壳能隙和超重核α衰变能等相关性质, 发现该模型能较好地再现实验结果。与此同时, 探索了原子核对称能系数对原子核质量公式的影响和超重稳定岛的可能位置。     

Systematic Study of Stability of Super Heavy Nuclei

A systematic overview on the characteristics of super heavy nuclei from Z=101 to Z=130 based on thedata by P. Moeller et al. is presented. The nuclei which have the biggest mean binding energy in each of their isotope chain show systematic regular behavior, indicating that the mean binding energy is a good criterion to classify super heavy nuclei by their stabilities. Further investigation on the nuclear data at and after Z=127 has been suggested.