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^<144>Sm的双声子四极和八极激发对^<16>O+^<144>Sm聚变反应能量的影响，表明核表面振动的非谐性强烈影响聚变势垒分布低于库仑势垒。利用这个结果，我们推导出 ^<144>Sm 的第一激发 2^+ 和 3^- 态的负四极矩。我们对^<16>O+^<148>Sm 聚变反应进行了类似的分析。 2. 我们研究了激发态的有限宽度对库仑势垒附近和以下能量的重离子聚变反应的影响，结果表明，无论扩散的相对重要性如何，有限宽度总是会降低沟道耦合的增强效果和逃逸宽度。 3. 我们分析了低能下^<16>O+^<154>Sm、^<186>W^<238>U聚变反应，结果表明：beta_6-变形、八极以及β和gamma振动以及2个核子转移反应发挥重要作用。 4. 我们研究了α衰变中的轫致辐射，结果表明（1）来自经典区、隧道区、混合区和壁面的所有贡献都起着重要作用（2）最终光谱由它们的干涉给出，并且变得比经典值 (3) 轫致辐射可能会消除确定 α 粒子和子核之间电势的模糊性。 5. 我们证明了在极前角区域中存在由核彩虹阴影引起的类似光辉的现象，作为一种新颖的焦散现象。 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）与裂变和重离子有关的跨越两能级问题中的非绝热跃迁碰撞（4）金属团簇中的电子态和（5）中能重离子碰撞中的碎片。