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

探索重质子核的核存在极限

• 批准号: ST/G008671/1
• 负责人: Robert Page
• 金额: $ 53.42万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FG008671%2F1
• 关键词: Exploring; limits; nuclear; existence; heavy

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，“一个原子核内可以束缚的质子和中子的数量限制是多少？”“这项研究提案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线的精确位置来回答这个问题的重要部分。质子和中子滴线是束缚核和非束缚核之间的边界。那些在质子滴注线上的人有如此多的过剩质子，以至于他们非常不稳定，并试图通过质子发射过程来实现更大的稳定性。我们将研究当质子变得不受束缚时，核的行为是如何受到影响的。沿着这片遥远的核景观海岸的核沿着应该显示出与为更稳定的核而优化的模型预测的行为的最大偏差。我们的研究将集中在靠近质子滴线的原子核，锡（Z=50）和铅（Z=82）之间的元素。从历史上看，这个区域一直是质子发射核的主要数据来源，主要是因为这里的质子发射发生在实验上可以达到的时间尺度上，仍然有效地与α或β衰变竞争。迄今为止发现的大约30个质子发射体的一个重要特征是，它们跨越了广泛的核变形，从球形核到橄榄球形状的其他核，长度比宽度长50%。球形核的质子发射可以用简单的模型很好地描述，理论描述的简单性使我们对这些核的结构有了很大的了解。强形变核质子发射的理论描述必然是相当不同的，已经提出了几个模型，并与现有的数据进行了比较。我们将利用新一代的实验方法来研究实验室中可以制造的最富含质子的原子核，跨越整个核变形范围。我们将寻找目前科学未知的原子核，并测量它们的质子和α衰变，首次研究选定原子核的激发态，并将重原子核直接质子发射的实验观察延长到纳秒（十亿分之一秒！）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核心的复杂而迷人的原子核世界的理解。

项目成果

a decay of At 194

194 处的衰变

• DOI: 10.1103/physrevc.79.064320
• 发表时间: 2009
• 期刊: Physical Review C
• 影响因子: 3.1
• 作者: Andreyev A

a decay of Pb 180 , 181

Pb 180 , 181 的衰变

• DOI: 10.1103/physrevc.80.054322
• 发表时间: 2009
• 期刊: Physical Review C
• 影响因子: 3.1
• 作者: Andreyev A

Detailed a -decay study of Tl 180

Tl 180 的详细 a 衰变研究

• DOI: 10.1103/physrevc.96.054327
• 发表时间: 2017
• 期刊: Physical Review C
• 影响因子: 3.1
• 作者: Andel B

ß -delayed fission of 192 , 194 At

- 192 , 194 At 的延迟裂变

• DOI: 10.1103/physrevc.87.014317
• 发表时间: 2013
• 期刊: Physical Review C
• 影响因子: 3.1
• 作者: Andreyev A

Decay of the 9 / 2 - isomer in Tl 181 and mass determination of low-lying states in Tl 181 , Au 177 , and Ir 173

Tl 181 中 9 / 2 - 异构体的衰变以及 Tl 181 、 Au 177 和 Ir 173 中低位态的质量测定

• DOI: 10.1103/physrevc.80.024302
• 发表时间: 2009
• 期刊: Physical Review C
• 影响因子: 3.1
• 作者: Andreyev A