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Macroscopic Quantum Tunneling in Nuclear Physics

核物理中的宏观量子隧道

基本信息

批准号：
09044051
负责人：
TAKIGAWA Noboru
金额：
$ 7.36万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

1. We showed that the anharmonicity of nuclear surface vibrations strongly influences the fusion barrier distribution by studying the effects of double phonon quadrupole and octupole excitations of ^<144>Sm on the ^<16>O+^<144>Sm fusion reactions at energies below the Coulomb barrier. Using this result, we deduced a negative quadrupole moment for both first excited 2^+ and 3^- states of ^<144>Sm. We performed a similar analysis for the ^<16>O+^<148>Sm fusion reactions. 2. We studied the influence of finite width of excited states on heavy-ion fusion reactions at energies near and below the Coulomb barrier, and showed that the finite width always reduces the enhancement effect of the channel coupling irrespective of the relative importance of the spreading and escape widths. 3. We analyzed the ^<16>O+^<154>Sm, ^<186>W ^<238>U fusion reactions at low energies and showed that.beta_6- deformation, octupole as well as beta and gamma vibrations and 2 nucleon transfer reactions play important roles. 4. We studied the bremsstrahlung in alpha decay and showed that (1) all the contributions from the classical region, tunneling region, mixed region and the wall play important roles (2) the final spectrum is given by their interference and becomes much smaller than the classical value (3) the bremsstrahlung might eliminate the ambiguity in determining the potential between the alpha particle and the daughter nucleus. 5. We showed the existence of a glory-like phenomenon caused by the shadow of a nuclear rainbow in the extremely forward angular region as a novel caustic phenomenon. 6. In addition, we studied (1) isospin dependence of nuclear incompressibility (2) screening effect by bound electrons in extremely low energy nuclear reactions (3) non-adiabatic transition in crossing two-level problems in connection with fission and heavy-ion collisions (4) electron states in metal clusters and (5) fragmentation in medium energy heavy-ion collisions.

1.通过研究能量低于库仑势垒的^&lt；144&gt；Sm的双声子四极激发和八极激发对^&lt；16&gt；O+&lt；144&gt；Sm聚变反应的影响，发现核表面振动的非谐性对聚变势垒分布有很大影响。利用这一结果，我们推导出了^&lt；144&gt；Sm的2^+和3^-激发态的负四极矩。我们对^&lt；16&gt；O+^&lt；148&gt；Sm融合反应进行了类似的分析。2.研究了激发态的有限宽度对库仑势垒附近和库仑势垒以下的重离子聚变反应的影响，结果表明，无论扩散宽度和逃逸宽度的相对重要性如何，有限宽度总是会减弱通道耦合的增强效应。3.我们分析了低能下的^&lt；16&gt；O+^&lt；154&gt；Sm，^&lt；186&gt；W^&lt；238&gt；U的聚变反应，结果表明，β_6-形变、八极以及β和伽马振动以及两个核子转移反应起着重要作用。4.对α衰变中的韧致辐射进行了研究，结果表明：(1)经典区、隧穿区、混合区和核壁的贡献都起着重要作用；(2)最终谱是由它们的干涉给出的，并且比经典值小得多；(3)韧致辐射可以消除在确定α粒子与子核之间的势时的模糊性。5.我们发现在极前方角区存在一种由核彩虹阴影引起的光辉现象，这是一种新的焦散现象。6.此外，我们还研究了(1)核不可压缩性的同位旋依赖性(2)极低能核反应中束缚电子的屏蔽效应(3)与裂变和重离子碰撞有关的交叉二能级问题中的非绝热跃迁(4)金属团簇中的电子态和(5)中能重离子碰撞中的碎裂。