Exploring the limits of nuclear existence for heavy proton-rich nuclei

探索重质子核的核存在极限

基本信息

批准号：
ST/G00871X/1
负责人：
John Smith
金额：
$ 12万
依托单位：
University of the West of Scotland
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FG00871X%2F1
关键词：
Exploring limits nuclear existence heavy

项目摘要

A fundamental question in nuclear physics is, 'what are the limits on the number of protons and neutrons that can be bound inside an atomic nucleus?' The aim of this research proposal is to answer a vital part of this question by determining more carefully than ever before the precise location of what is known as the proton drip line. The proton and neutron drip lines are the borders between bound and unbound nuclei. Those at the proton drip line have such a large excess of protons that they are highly unstable and try to achieve greater stability through the process of proton emission. We will investigate how nuclear behaviour is affected when protons become unbound. Nuclei along this distant shore of the nuclear landscape should show the greatest deviations from the behaviour expected from predictions of models optimised for more stable nuclei. Our investigations will focus on nuclei close to the proton drip line, for elements between tin (Z=50) and lead (Z=82). Historically, this region has been the primary source of data on proton-emitting nuclei, largely because here the proton emission occurs on an experimentally accessible timescale that still competes effectively with alpha or beta decay. One important feature of the 30 or so proton emitters discovered to date is that they span a wide range of nuclear deformations, ranging from spherical nuclei to others that are rugby ball shaped and are up to 50% longer than they are wide. Proton emission from spherical nuclei is well described using simple models and the simplicity of the theoretical description has allowed a great deal to be learnt about the structure of these nuclei. The theoretical descriptions for proton emission from strongly deformed nuclei are necessarily rather different and several models have been proposed and compared with the available data. We will exploit a new generation of experimental methods to study the most proton-rich atomic nuclei that can be made in the laboratory, spanning the entire range of nuclear deformations. We will search for nuclei presently unknown to science and measure their proton and alpha decays, study excited states in selected nuclei for the first time and extend experimental observations of direct proton emission from heavy nuclei to lifetimes of nanoseconds (billionths of a second!) and even shorter. The results of our experiments will be compared with the theoretical predictions in order to improve our understanding of the complex and fascinating world of the nuclei at the heart of every atom.

核物理学中的一个基本问题是：“可以在原子核内结合的质子和中子的数量有什么限制？”这项研究建议的目的是通过比以往任何时候都更仔细地确定所谓的质子滴管线的确切位置来回答这个问题的重要部分。质子和中子滴头是结合和未结合核之间的边界。那些在质子滴管线上的质子太大的质子，以至于它们高度不稳定，并试图通过质子发射过程实现更大的稳定性。我们将研究质子未结束时如何影响核行为。沿核景观的遥远海岸的核应显示出与针对更稳定的核优化的模型的预测所期望的行为的最大偏差。我们的研究将集中于接近质子滴管线的核，对于锡（z = 50）和铅（z = 82）之间的元素。从历史上看，该区域一直是质子发射核的主要数据来源，这主要是因为在这里质子发射发生在实验可访问的时间表上，该时间表仍然与Alpha或beta衰减有效竞争。迄今为止发现的30个左右的质子发射器的一个重要特征是，它们跨越了广泛的核变形，从球形核到其他橄榄球球形，并且比宽的其他核核。使用简单模型很好地描述了来自球形核的质子发射，理论描述的简单性使人们可以了解这些核的结构。质子核的质子发射的理论描述必然是不同的，并且已经提出了几种模型并将其与可用数据进行了比较。我们将利用新一代的实验方法来研究可以在实验室中制成的最富含质子的原子核，从而涵盖整个核变形范围。我们将在科学目前搜索目前未知的原子核，并测量其质子和α衰变，首次研究选定核中的激发态，并将直接质子发射的实验性观察从重核从重核从纳米角度的寿命（十亿分之一！）延伸到寿命，甚至更短。我们的实验结果将与理论预测进行比较，以提高我们对每个原子中心核的复杂和迷人世界的理解。