ISOL-SRS: ISOL Beam Storage Ring Spectrometer

我们周围的元素和构成我们身体的元素主要是稳定的，但我们知道这些元素是在暴力的天体物理场景中锻造的。这段激烈历史的痕迹可以在令人震惊的新的详细天文观测中找到，这些观测来自爆炸恒星的元素丰度，被归因于单次爆炸事件后物质凝聚的陨石包裹体，以及对伽马射线发射的观测，表明这些过程在我们的宇宙中仍在进行。在这些爆炸情景中，元素的合成涉及到不稳定核的核反应。这些不稳定核的未知结构和反应严重影响了我们对元素起源的理解，我们现在看到的元素在我们周围处于相对静止的状态，以及它们形成的恒星环境的性质和动力学。随着我们开始探索这些核的性质，在壳层结构的演化上发现了令人惊讶的结果，这表明我们在稳定核中发现的情况不能简单地外推到不稳定系统。自然界比我们预期的要丰富和多样得多，导致了由核相互作用的基本性质驱动的新的壳结构。这些壳结构的位置微妙，并与原子核的形状密切相关。一个这样的例子是表现出永久静态八极形变的梨形原子核。这为寻找有限的原子电偶极矩提供了一个非常有前途的实验室，它表明了超越粒子物理标准模型的CP破坏。使用激光精确测量不稳定核原子能级的演化，反过来可以提供对原子核潜在电荷半径的测量。这对于晕核的研究尤其重要，晕核展示了一种几乎纯粹的中子物质。上述科学需要对不稳定核的结构和反应进行精确测量。此外，这些研究需要在适当的能量条件下进行，在那里这些性质可以得到最好的探测。新的TSR重离子存储环将位于欧洲核子研究中心的Isolde设施。这将是全球独一无二的设施。伊索尔德是世界领先的放射性束流生产设施。在新的升级之后，这些放射性束流将被加速到适合精密反应研究的能量范围。这些光束将被注入存储环，在那里它们可以被快速冷却，以产生非常高质量的放射性光束，从而能够使用非常薄的纯气体目标进行超高分辨率的核反应测量，或使用激光测量基态性质。在每种情况下，存储环都允许在放射性束以~1 MHz的频率在环中循环时对其进行重复探测，从而确保高光度与高精度相结合。对于较重的放射性物质，由于原子与气体靶的碰撞，环中束流的寿命会显著缩短。在这种情况下，可以从环中提取高质量的光束，并将其注入到新型螺线管磁体和探测器系统中。因此，英国社区提议与TSR储存环一起使用的整个isol-srs光谱仪系统将使不稳定核的反应和性质的精确研究在Isolde放射束设施CERN产生的广泛质量和同位素范围内取得重大突破。

The elements we see around us, and that constituent our bodies, are predominantly stable, yet we know these were forged in violent astrophysical scenarios. The traces from this violent history can be found in sensational new detailed astronomical observations of element abundances from exploding stars, meteoritic inclusions attributed to condensation of material following single explosive events, and observations of gamma-ray emission indicating these process are still ongoing in our universe. The synthesis of the elements in these explosive scenarios involves nuclear reactions involving unstable nuclei. The unknown structure and reactions of these unstable nuclei critically affects our understanding of the origin of elements we now see in a relatively quiescent state around us, and the nature and dynamics of the stellar environments in which they formed. As we have begun to explore the properties of these nuclei, surprising results have been found on the evolution of shell structure, indicating what we find to be the case in stable nuclei, cannot be simply extrapolated to unstable systems. Nature is far more rich and diverse then we anticipated, leading to new shell structures driven by the underlying nature of the nuclear interaction. The locations of these shell structures are subtley and intimately associated with the shapes of nuclei. One such example are Pear-shaped nuclei exhibiting permanent static octupole deformations.These provide a very promising laboratory to search for finite atomic electric dipole moments, indicative of CP violation beyond the Standard Model of Particle Physics. Precision measurements of the evolution of atomic levels of unstable nuclei using lasers, can in turn provide measurements of the underlying charge radius of the nucleus. This is particularly important for the study of halo nuclei, which exhibit an almost pure mantle of neutron matter.The science described above requires precision measurements of the structure and reactions of unstable nuclei. Furthermore, the studies need to be performed in the appropriate energy regime where these properties can be best probed. The new TSR heavy ion storage ring will be located at the ISOLDE facility CERN. This will be a unique facility worldwide. ISOLDE is the world's leading facility for the production of radioactive beams. Following new upgrades, these radioactive beams will be accelerated to the energy range perfect for precision reaction studies. These beams will be injected into the storage ring where they can be rapidly cooled to give very high quality radioactive beams enabling ultra high resolution measurements of nuclear reactions to be performed using very thin, pure gas targets or measurements of the ground-state properties using lasers. In each case the storage ring allows a repeated probing of the radioactive beam as it circulates with a frequency ~1 MHz in the ring, ensuring high luminosity is combined with high precision. For heavier radioactive species, the lifetime of the beam in the ring is significantly reduced by atomic collisions with the gas target. In this case, the high quality beam can be extracted from the ring and injected into a novel solenoidal magnet and detector system. The overall ISOL-SRS spectrometer systems proposed by the UK community for use in conjunction with the TSR storage ring will therefore enable a major breakthrough in precision studies of the reactions and properties of unstable nuclei across the vast range of masses and isotopes produced by the ISOLDE radioactive beams facility, CERN.