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The ISOL-SRS project

 

 

 

 

 

Description & Physics case:


Physics case

 

Physics Case:

Europe is currently constructing the next generation of radioactive-ion beam facilities, produced either by the ISOL (Isotope Separator On-Line) method (HIE-ISOLDE, SPIRAL2 and SPES) or by the complementary “in-flight” method (FAIR). The first of these planned to come on-line, HIE-ISOLDE at CERN, will provide a wide diversity of neutron rich and neutron deficient accelerated radionuclides, ranging from 6He to 228Ra at 5.5 - 10MeV/u, available for users from 2015. The experimental programmes at this facility will address the major challenge of the fundamental understanding of nuclear structure in terms of the underlying many-body interactions between nucleons. Descriptions of nuclei having more than a few nucleons are semi-phenomenological in origin and cannot be reliably applied to nuclei far from stability. It is therefore crucial to measure the properties of nuclei at the extremes of stability such as the evolution of shell structure and collective phenomena. The radioactive beam facilities also aim at understanding the universe through its history of stellar activity where nuclear reactions play essential roles. In particular, in the violent maelstrom of explosive processes such as novae, X-ray bursters and supernovae the heavy elements are made in complex networks of reactions of unstable nuclei and beta-decays. To understand these processes quantitatively and identify the astronomical sites where they occur requires a wealth of information on many of the key reactions involving unstable nuclei.

The ability to address the key science goals will require the precisely tuneable energies, wide range of nuclides uniquely available from HIE-ISOLDE for the necessary flexibility in designing experiments, the major improvements in beam quality and major advances in spectrometer design, providing a facility for research at the precision frontier. The ISOL-SRS spectrometer proposed here is ideally suited for exclusive measurements of reactions of unstable nuclei, so that nucleosynthesis in stellar processes can be understood and evolving theories of nuclear structure can be rigorously tested.

Applications:

(i) Studies of Capture Reactions and the production of p-nuclei:

The goal is to understand the astrophysical reaction mechanism for proton-rich nuclei in violent astrophysical processes by direct measurements of the reaction cross-section.

(ii) Nuclear Astrophysics through Transfer Reactions
The goal is to understand the astrophysical reaction mechanism for proton-rich and neutron-rich nuclei in violent astrophysical processes, by surrogate methods to determine the reaction cross-section.

(iii) Shell evolution
The goal is to understand the ways in which nucleons interact with each other in complex nuclei and how their interaction affects nuclear structure, by probing the behaviour of a single nucleon across a wide range of isotopes for spherical nuclei.

(iv) Nuclear shapes
The goal is to understand the ways in which nucleons interact with each other in complex nuclei and how their interaction affects nuclear structure, by making precise measurements of electromagnetic matrix elements in deformed nuclei. For pear-shaped nuclei, there is an additional aim to quantify the results of searches for atomic EDMs that would indicate CP-violation beyond the Standard Model.

(v) Nuclear ground state properties studied with lasers
The goal is to measure ground state properties that would characterise halo-like structure in light nuclei, important for understanding the ways in which nucleons interact with each other in light nuclei and how their interaction affects nuclear structure.