HIE-ISOLDE

HIE-ISOLDE
Name	HIE-ISOLDE
Institution	CERN
Location	Geneva, Switzerland
Type	Linear accelerator
Particle	Radioactive ion beams
Energy	Up to 10 MeV/u

HIE-ISOLDE. The High Intensity and Energy ISOLDE facility is a major upgrade to the world's leading radioactive ion beam facility, ISOLDE, located at the European Organization for Nuclear Research (CERN). It significantly enhances the energy and intensity of beams available for nuclear physics experiments, enabling pioneering studies far from the valley of stability. This advanced installation allows researchers to probe the fundamental properties of atomic nuclei and test the limits of nuclear models under extreme conditions.

Overview

HIE-ISOLDE represents a critical evolution of the long-standing ISOLDE facility, which has been operational since 1967. The project was initiated to address the growing demand for higher-energy beams to explore nuclear structure and astrophysics processes. Its primary function is to post-accelerate the exotic isotopes produced by the ISOLDE target and source system using a state-of-the-art superconducting linear accelerator. This capability places HIE-ISOLDE at the forefront of facilities like RIKEN's RI Beam Factory and the Facility for Rare Isotope Beams (FRIB) in the United States. The project involved a large international collaboration of institutes and was formally approved by the CERN Research Board.

Technical Specifications

The core of HIE-ISOLDE is a superconducting linear accelerator (linac) based on quarter-wave resonators made of high-purity niobium. This design allows the acceleration of ions to energies variable between 0.45 and 10 MeV per nucleon, a substantial increase over the previous REX-ISOLDE system. The linac operates at a frequency of 101.28 MHz and is cooled by a dedicated cryogenic plant to temperatures near 4.2 Kelvin. The facility can handle a wide range of ion species, from light nuclei like beryllium to heavy species like uranium, with intensities boosted by upgrades to the ISOLDE target station. Beam delivery is managed by a sophisticated suite of magnetic and electrostatic elements for precise focusing and transport to various experimental stations.

Scientific Programme

The scientific programme at HIE-ISOLDE is exceptionally broad, spanning nuclear structure, nuclear astrophysics, and fundamental interactions. Key experiments investigate shell evolution and collective phenomena in exotic nuclei through techniques like Coulomb excitation, transfer reactions, and deep-inelastic scattering. Nuclear astrophysics studies focus on measuring reaction rates critical for understanding stellar nucleosynthesis in environments like supernovae and neutron star mergers. The facility also hosts experiments probing fundamental symmetries via precise measurements of nuclear properties and provides beams for interdisciplinary research in fields like solid-state physics and life sciences. This work is conducted by numerous collaborations, including the MINIBALL and T-REX spectrometer groups.

History and Development

The concept for HIE-ISOLDE emerged in the early 2000s following the success of its predecessor, the REX-ISOLDE post-accelerator. A detailed design phase began around 2005, leading to formal approval from the CERN Council in 2009. Construction and installation of the superconducting linac modules took place in stages between 2013 and 2018, with the first beams delivered to experiments in 2015. The project was a collaborative effort involving many institutions across Europe, such as the University of Jyväskylä and the University of Liverpool, contributing key components. Its completion marked the culmination of the ISOLDE facility's multi-stage upgrade plan initiated in the 1990s.

Impact and Discoveries

HIE-ISOLDE has already yielded significant impacts on the field of nuclear physics. It has enabled the first detailed spectroscopy of numerous isotopes near the drip lines, revealing unexpected shapes and new magic numbers. Landmark studies include the investigation of the evolution of nuclear shells in the region of tin isotopes and precise measurements of beta-delayed neutron emission probabilities. The facility has provided crucial data for refining theoretical models, such as those from the University of Tennessee and GSI Helmholtz Centre for Heavy Ion Research. Its high-quality beams have also facilitated breakthroughs in applied research, including the development of novel medical isotopes and materials science studies.

Future Prospects

The future of HIE-ISOLDE is tightly integrated with the broader evolution of CERN's infrastructure and the global nuclear physics landscape. Ongoing developments focus on increasing beam intensities further and expanding the range of available isotopes through target and ion source improvements. The facility is expected to play a complementary role to next-generation projects like the Gamma Factory at CERN and the Advanced Rare Isotope Laboratory (ARIEL) at TRIUMF. Its long-term scientific programme will continue to address key questions in nuclear physics, contributing essential knowledge to international efforts like those outlined by the International Union of Pure and Applied Physics (IUPAP).

Category:Particle accelerators Category:CERN Category:Nuclear physics facilities