Nuclear Reaction Mechanisms for Synthesis of Superheavy Elements

超重元素合成的核反应机制

基本信息

批准号：
13640278
负责人：
ABE Yasuhisa
金额：
$ 1.92万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Experiments of syntheses of the superheavy elements have been made more or less empirically, because there have been no reliable reaction theory for such unstable systems. Nevertheless, we want to synthesize as heavier elements as possible in order to know how many elements exist. According to the experiences, production rates decrease dramatically as the charge number Z of the element increases and thus, machine time is required enormously. Therefore, it is crucial to know optimum conditions for the productions, in other words, precise theoretical predictions of excitation functions for xn reaction channels, which is exactly the purpose of the present project. Now, it is achieved, as is shown in the publications, the list of which is attached below.Most unknown theoretically was mechanisms of the fusion of massive heavy ions which leads to the formation of superheavy compound nuclei. We have employed a Langevin Approach, which was firstly proposed by the head investigator of the prese … More nt project for description of nuclear collective motions, and was found to be successful for fusion of heavy ions and subsequent fission. We have developed the unique theoretical framework, i.e., the two-step model for synthesis of superheavy elements, which is now recognized as a canonical theoretical model, and was presented in the 2nd International Conference on Chemistry and Physics of Transactinide Elements, held at Napa, California, USA, Nov. 16-20, 2003, as an Introductory Review of Nuclear Reaction Theory.Furthermore, we have succeeded in reproducing the available data of the experiments with so-called hot and cold fusion paths. Now, we are making predictions on the elements Z=113 and 114, which are expected to be useful in planning experiments, and at the same time, are waiting for experimental confirmation. A new statistical code has been developed which enables us to follow time evolution of the cooling process of the superheavy compound nuclei. This is now open for potential users. Less

超重元素的合成实验或多或少都是凭经验进行的，因为对于这种不稳定的系统还没有可靠的反应理论，但我们希望合成尽可能多的重元素，以便了解存在多少元素。根据经验，随着元件电荷数 Z 的增加，生产率急剧下降，因此需要大量的机器时间。因此，了解生产的最佳条件至关重要，换句话说，对 xn 的激励函数进行精确的理论预测。反应通道，即现在，它已经实现，如出版物所示，其列表附在下面。理论上最未知的是导致超重复合核形成的大量重离子聚变机制。我们采用了朗之万方法，该方法首先由当前项目的首席研究员提出，用于描述核集体运动，并被发现对于重离子聚变和随后的裂变是成功的，我们开发了独特的理论。框架，即超重元素合成的两步模型，现已被公认为规范的理论模型，并于11月在美国加利福尼亚州纳帕举行的第二届反锕系元素化学与物理国际会议上提出2003年16-20日，作为核反应理论的介绍性回顾。此外，我们已经成功地再现了所谓的热实验的可用数据现在，我们正在对Z=113和114元素进行预测，预计这对规划实验很有用，同时正在等待实验确认，新的统计代码已经开发出来。使我们能够跟踪超重化合物核冷却过程的时间演化，现在向潜在用户开放。