AGATA: Precision Spectroscopy of Exotic Nuclei

AGATA是一种专门设计的工具，用于实现激发核态的精确光谱。一台强大的伽马射线光谱仪对研究核结构至关重要，而AGATA作为欧洲领先的伽马射线设备，在其科学计划中需要束内伽马射线能谱能力的所有欧洲主要设施都有非常高的需求。因此，AGATA科学涉及面特别广，与这些设施的核结构物理长期计划密切相关。该科学计划与STFC科学挑战很好地结合在一起，由此产生了优先事项，STFC核物理路线图强调了这一点。这些问题包括：是什么决定了核存在的限度，在核束缚的限度上是否有新的结构和对称性形式？复杂原子核中出现简单图案的机制是什么？例如，为了理解有效核相互作用的同位旋依赖关系，从单个核子的性质来解释集体现象，以及确定核存在的极限，研究核稳定极限的结构是至关重要的。很明显，我们教科书上关于核结构的许多想法都需要修改。例如，核壳模型中幻数的值不再是神圣不可侵犯的，核子-核子相互作用的强度意味着中子(质子)壳层闭合的位置随着质子(中子)数的变化而变化。现在可以存在的富含中子的原子核的数量预计会比之前认为的要多得多：改进的原子核理论，包括对关联性和聚集性的更现实的估计，预测了似乎正在不断后退的中子滴线。AGATA的高分辨率与新的高强度放射性离子束设施相结合，将使我们应对这些新出现的挑战的能力发生重大变化。

AGATA is a tool specifically designed to enable precision spectroscopy of excited nuclear states. A powerful gamma-ray spectrometer is essential for nuclear structure studies, and AGATA - as Europe's leading gamma-ray device - is in very high demand at all the major European facilities that require in-beam gamma-ray spectroscopy capability for their science programmes. The AGATA science is, therefore, exceptionally broad-ranging and is strongly connected to the long-term plans for nuclear-structure physics at these facilities. The science programme is well aligned with the STFC Science Challenges, from which priorities emerge, highlighted in the STFC Nuclear Physics Roadmap. These include: What determines the limits of nuclear existence and are there new forms of structure and symmetry at the limits of nuclear binding? What mechanism drives the emergence of simple patterns in complex nuclei? The study of structure at the very limits of nuclear stability is crucial, for example, in order to understand the isospin dependence of the effective nuclear interaction, to explain collective phenomena from the properties of the individual nucleons, and to establish the limits of nuclear existence. It has become clear that many of our textbook ideas of nuclear structure need to be revised. For example, the values of the magic numbers in the nuclear shell model are no longer sacrosanct and the strength of the nucleon-nucleon interaction means that the position of the neutron (proton) shell closure varies with the proton (neutron) number. The number of neutron-rich nuclei which can exist is now expected to be far greater than previously thought: improvements nuclear theory, including more realistic estimates of correlations and clustering, predict a neutron drip-line which seems to be constantly receding. The combination of the high resolving power of AGATA with the new high-intensity radioactive ion beam facilities will provide a step-change in our capability to address these emerging challenges.