A lanthanum-bromide array for precision electromagnetic-transition measurements in light nuclei at the Birmingham MC40 cyclotron.

核物理学中最大的挑战之一是理解核力(核尺度上的强相互作用)如何导致在原子核中观察到的一系列性质。核子尺度上的强相互作用是亚核子水平上相同相互作用的表现，其中夸克和胶子是适当的自由度。如何将这些映射到核力的特征上，是原子核理论从头算(第一性原理)方法的领域。有几种这样的方法，其中一些使用手征有效场论来产生相互作用，另一些方法是模拟自由质子和中子的核子-核子相互作用，然后将其嵌入到原子核中。它们都能够计算质量最大为12的轻核，例如碳-12，并且(在某些情况下)正在向更重的系统发展。为了取得进一步进展，需要有实验数据来测试和区分各种方法。对于一些系统，这些数据是存在的，对于其他系统，特别是对于碳-12的激发态，这些数据并不存在。此外，对于有数据的系统，精度通常不足以对理论提出挑战。目前设备赠款的目的是开发一个总部设在英国的设施，能够提供电磁转换率的精确测量。这样的测量是一个关键的实验观测，所有的理论都可以计算，因此可以进行测试。我们将围绕我们现有的MC40回旋加速器建造一个设施，将伽马射线探测与当前的带电粒子探测器技术和仪器相结合，以创造这一科学机会。这笔资金将用于购买一组溴化镧闪烁体探测器，以实现精确的电磁衰减测量。

One of the greatest challenges in nuclear physics is to understand how the nuclear force (the strong interaction on the nuclear scale) results in the range of properties observed in nuclei. The strong interaction on the nuclear scale is a manifestation of the same interaction on a sub-nucleon level, where the quarks and gluons are the appropriate degrees of freedom. How these map on to the features of the nuclear force is the domain of ab initio (first principles) approaches to nuclear theory. There are several such methods, some of which use chiral effective field theory to generate the interactions, others which take an approach of modelling the nucleon-nucleon interaction of free protons and neutrons and then embedding that in the nucleus. All are able to produce calculations of light nuclei up to mass 12, e.g. carbon-12, and are (in some cases) progressing to heavier systems. In order to make further progress there is a need for experimental data to test and discriminate between the approaches. For some systems these data exist, for others, particularly for excited states of carbon-12, the data do not exist. Also, for systems where there are data, often the precision is insufficient to provide challenge to theory. The aim of the present equipment grant is to develop a UK-based facility capable of delivering precision measurements of electromagnetic transition rates. Such measurements are a key experimental observable which all theories can compute and hence can be tested. We will construct a facility around our existing MC40 cyclotron to combine gamma-ray detection with current charged particle detector technology and instrumentation to create this scientific opportunity. The funding is to purchase an array of Lanthanum Bromide scintillator detectors to permit precision electromagnetic decay measurements.