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Edinburgh Nuclear Physics Group Consolidated Grant Proposal

爱丁堡核物理小组综合赠款提案

基本信息

批准号：
ST/V001051/1
负责人：
Philip J Woods
金额：
$ 162.3万
依托单位：
University of Edinburgh
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2021
资助国家：
英国
起止时间：
2021 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FV001051%2F1
关键词：
Edinburgh Nuclear Physics Group Consolidated

项目摘要

The elements we see around us today are still being forged by nuclear reactions in stars and some were first produced as early the primordial big-bang. Understanding the different astrophysical origins and production mechanisms of the elements is a fundamental challenge in science. Remarkable new astronomical observations, including those of neutron star mergers by Gravitational Wave, and electromagnetic radiation measurements, provide a challenge to nuclear physics to determine the key nuclear properties required to understand and model element production at these astrophysical sites. In the case of neutron star mergers and the production of heavy elements beyond Iron, this involves explosive reactions on isotopes with 20-30 neutrons more than the stable isotopes we see around us today. Here on the earth we are now able to produce these exotic isotopes for the first time using modern heavy ion accelerators. The Edinburgh Group has led the development of a key detection system, AIDA, to perform these measurements on these isotopes as they begin their long decay journey back to stability. In a new development within the Group we will be using ion traps to momentarily incarcerate these exotic isotopes to precisely measure their masses, a fundamental property that determines how far from stability the production of heavy elements proceeds.Heavy elements can also be produced over a long period of time by neutron fusion reactions during quiescent phases of stellar evolution, tracking closely to the line of stability. In this case, the reaction probabilities need to be measured directly in nuclear reaction measurements with intense neutron beams. The origin of the neutrons in stellar environments occurs by very low energy fusion reactions between charged particles and requires quantum tunnelling to proceed. These reactions have very low reaction probabilities and will be measured at a new underground accelerator facility LUNA MV where the background from cosmic rays is low. At the same facility, we will explore the reaction rate between Carbon nuclei that determines whether massive stars explode as supernovae or whither away into white dwarfs. We will measure a reaction occurring during core collapse supernovae explosions that controls the amount of gamma-rays observed from the subsequent decays of radioactive nuclei after the explosion using a storage ring where the radioactive ions repeatedly traverse a Helium gas target and the reactions are measured with a new detector system, CARME, developed by the Group. This system will also be used to measure reactions occurring in novae explosions that control the production of elements ejected into the cosmos and isotopic ratios measured in pre-solar grains found in meteorites. We will also explore the evolution of nuclear shell structures far from stability, including phenomena at magic numbers, representing particular stable quantum configurations. These structures leave behind their fingerprints in the abundances of the elements. Finally we return to the original elemental origin, the Big Bang. Here astronomical observations, of the microwave background radiation and light element abundances, now supercede the precision of nuclear reaction measurements required to model the Big Bang so we will measure a key reaction for the Big Bang using CARME on the storage ring representing a completely new approach to such measurements, where we hope to improve the precision and eliminate certain systematic sources of error. Such improved measurements can for example limit the possible existence of exotic particles beyond the Standard Model of Particle Physics.

我们今天看到的我们周围的元素仍然是由恒星中的核反应形成的，其中一些最早是在原始大爆炸的时候产生的。理解这些元素的不同天体物理起源和产生机制是科学中的一个根本挑战。引人注目的新天文观测，包括引力波中子星合并的天文观测和电磁辐射测量，对核物理提出了挑战，以确定理解这些天体物理地点的元素生产并对其建立模型所需的关键核性质。在中子星合并和生产铁以外的重元素的情况下，这涉及到同位素上的爆炸性反应，中子比我们今天看到的稳定同位素多20-30个中子。在地球上，我们现在第一次能够使用现代重离子加速器生产这些奇异的同位素。爱丁堡小组领导了一个名为AIDA的关键探测系统的开发，以在这些同位素开始恢复稳定的漫长衰变旅程时对它们进行这些测量。在该小组内部的一项新发展中，我们将使用离子陷阱来暂时捕获这些奇异的同位素，以精确测量它们的质量，这是决定重元素生产离稳定有多远的一个基本性质。重元素也可以在恒星演化的静止阶段通过中子聚变反应在很长一段时间内产生，密切跟踪稳定线。在这种情况下，需要在用强中子束进行核反应测量时直接测量反应几率。恒星环境中中子的起源是带电粒子之间的极低能量聚变反应，需要量子隧道才能进行。这些反应的概率非常低，将在一个新的地下加速器设施露娜MV上进行测量，那里的宇宙射线背景很低。在同一设施中，我们将探索碳核之间的反应速度，这决定了大质量恒星是以超新星的形式爆炸，还是向外变成了白矮星。我们将使用一个储存环测量核心坍塌超新星爆炸期间发生的反应，该反应控制从爆炸后放射性核随后的衰变中观察到的伽马射线的量，其中放射性离子反复穿过氦气体目标，并用专家组开发的新的探测器系统CARME测量反应。该系统还将用于测量新星爆炸中发生的反应，这些反应控制喷射到宇宙中的元素的产生，以及在陨石中发现的太阳前颗粒中测量的同位素比率。我们还将探索远离稳定性的核壳结构的演化，包括代表特定稳定量子组态的幻数现象。这些结构在元素的丰度上留下了它们的指纹。最后，我们回到最初的元素起源--大爆炸。在这里，对微波背景辐射和轻元素丰度的天文观测，现在取代了对大爆炸建模所需的核反应测量的精度，所以我们将使用存储环上的Carme来测量大爆炸的关键反应，这代表了一种全新的测量方法，我们希望提高精度并消除某些系统误差来源。例如，这种改进的测量可以限制超出粒子物理标准模型的奇异粒子的可能存在。