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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.

我们今天在我们周围看到的元素仍然是通过恒星中的核反应形成的，有些元素是在原始大爆炸早期就产生的。了解元素的不同天体物理起源和产生机制是科学中的一个基本挑战。引人注目的新天文观测，包括引力波和电磁辐射测量的中子星星合并，提供了一个挑战，核物理学，以确定关键的核特性所需的理解和模型元素生产在这些天体物理站点。在中子星星合并和产生铁以外的重元素的情况下，这涉及到同位素的爆炸反应，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关键检测系统AIDA的开发，以在这些同位素开始漫长的衰变过程中恢复稳定时对它们进行测量。在研究小组的一项新进展中，我们将使用离子阱暂时监禁这些外来同位素，以精确测量它们的质量，这是决定重元素产生过程中离稳定性有多远的基本性质。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，紧密跟踪稳定线。在这种情况下，反应概率需要直接测量在核反应测量与强中子束。恒星环境中的中子起源于带电粒子之间的极低能量聚变反应，需要量子隧穿才能进行。这些反应具有非常低的反应概率，将在新的地下加速器设施LUNA MV进行测量，那里的宇宙射线背景很低。在同一个设施中，我们将探索碳原子核之间的反应速率，这决定了大质量恒星是爆炸成超新星还是爆炸成白色矮星。我们将测量在核心坍缩超新星爆炸期间发生的反应，该反应控制爆炸后从放射性核的后续衰变中观察到的伽马射线量，使用存储环，其中放射性离子反复穿过氦气目标，并使用新的探测器系统CARME测量反应。该系统还将用于测量新星爆炸中发生的反应，这些反应控制着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。我们还将探讨远离稳定的核壳结构的演化，包括幻数现象，代表特定的稳定量子构型。这些结构在元素丰度中留下了它们的指纹。最后，我们回到最初的元素起源，大爆炸。在这里，微波背景辐射和轻元素丰度的天文观测现在取代了模拟大爆炸所需的核反应测量的精度，因此我们将使用CARME在储存环上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源。这种改进的测量可以例如限制超出粒子物理学标准模型的外来粒子的可能存在。