ISOL-SRS: ISOL Beam Storage Ring Spectrometer

我们周围看到的构成我们身体的元素，主要是稳定的，但我们知道，这些元素是在剧烈的天体物理场景中形成的。这段狂暴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，归因于单一爆炸事件后物质凝聚的陨石内含物，以及伽马射线发射的观测表明这些过程仍在我们的宇宙中进行。在这些爆炸情景中，元素的合成涉及不稳定原子核的核反应。这些不稳定原子核的未知结构和反应严重影响了我们对元素起源的理解，我们现在看到的是我们周围相对静止的状态，以及它们形成的恒星环境的性质和动力学。当我们开始探索这些原子核的性质时，在壳结构的演化上发现了令人惊讶的结果，表明我们在稳定原子核中发现的情况，不能简单地外推到不稳定的系统中。自然界比我们预期的要丰富和多样得多，这导致了由核相互作用的潜在性质驱动的新壳结构。这些壳结构的位置与原子核的形状有着微妙而密切的联系。一个这样的例子是梨形核表现出永久的静态八极变形。这为寻找有限原子电偶极矩提供了一个非常有前途的实验室，它指示了超越粒子物理标准模型的CP违反。利用激光精确测量不稳定原子核的原子能级演变，可以反过来提供原子核的潜在电荷半径的测量。这对晕核的研究尤其重要，晕核表现出几乎纯中子物质的地幔。上述科学需要对不稳定原子核的结构和反应进行精确测量。此外，研究需要在适当的能量状态下进行，这样才能最好地探测这些特性。新的TSR重离子储存环将位于欧洲核子研究中心的ISOLDE设施。这将是世界上独一无二的设施。ISOLDE是世界上生产放射性光束的领先设备。随着新的升级，这些放射性光束将被加速到精确反应研究的完美能量范围。这些光束将被注入存储环中，在那里它们可以快速冷却，从而产生非常高质量的放射性光束，从而可以使用非常薄的纯气体靶或使用激光测量基态特性来进行超高分辨率的核反应测量。在每种情况下，存储环允许重复探测放射性光束，因为它在环中以1兆赫的频率循环，确保高亮度与高精度相结合。对于较重的放射性物质，环中光束的寿命因与气体靶的原子碰撞而大大缩短。在这种情况下，高质量的光束可以从环中提取并注入到一种新型的电磁磁铁和探测器系统中。因此，由英国社区提出的与TSR存储环一起使用的整体isoll - srs光谱仪系统，将使欧洲核子研究中心（CERN） ISOLDE放射性束流设施产生的大量质量和同位素的不稳定核的反应和性质的精确研究取得重大突破。

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.