ISOLDE

ISOLDE. The Isotope Separator On-Line facility, or ISOLDE, is a world-leading research installation dedicated to the production and study of radioactive atomic nuclei. Located at the European Organization for Nuclear Research (CERN) near Geneva, it utilizes proton beams from the Proton Synchrotron Booster to create exotic isotopes for a wide array of fundamental and applied research. Since its inception, the facility has been instrumental in advancing our understanding of nuclear structure, astrophysical processes, and fundamental symmetries, while also contributing to interdisciplinary research in fields like solid-state physics and life sciences.

Overview

ISOLDE operates as a unique on-line isotope separator, coupling its production targets directly to a powerful mass spectrometer for rapid isotope selection. This setup allows scientists to investigate nuclei far from the valley of beta-stability, which are often short-lived and cannot be found in nature. The research conducted spans numerous domains, including tests of the Standard Model, studies of nuclear reactions that power supernovae, and the development of novel techniques for medical imaging. The facility's continuous upgrades, such as the HIE-ISOLDE project for post-acceleration, have significantly expanded its experimental reach and scientific output.

History and development

The concept for ISOLDE was first proposed in the 1960s by a collaboration of European nuclear physicists seeking to explore new regions of the nuclear chart. The original facility, known as ISOLDE 1, began operations in 1967, using a beam from the CERN Synchro-Cyclotron. Its immediate success in producing pure beams of radioactive isotopes led to the construction of the improved ISOLDE 2 in 1974. A major relocation occurred in 1992 when the facility was moved to the newly constructed Proton Synchrotron Booster, providing a more intense and flexible proton driver. Subsequent milestones include the launch of the REX-ISOLDE experiment for post-acceleration in 2001 and the major HIE-ISOLDE upgrade, which commenced its physics program in 2015 to deliver higher-energy beams.

Scientific research and achievements

Research at ISOLDE has yielded profound insights into the structure of atomic nuclei, directly testing models like the shell model and revealing phenomena such as nuclear halo states and shape coexistence. In nuclear astrophysics, precise measurements of nuclear masses and beta-decay rates have clarified the pathways of the rapid neutron capture process responsible for creating heavy elements in the cosmos. The facility has also conducted pioneering searches for physics beyond the Standard Model through studies of beta-decay correlations and measurements of fundamental properties. Applied research includes the use of radioactive probes to study defects in semiconductors and the development of isotopes like scandium-44 for positron emission tomography.

Technical description

The ISOLDE facility begins with a pulsed proton beam from the Proton Synchrotron Booster, which impacts a thick target material, such as uranium carbide or tantalum, inducing spallation, fission, or fragmentation reactions. The produced radioactive atoms diffuse out of the heated target and are ionized, often using advanced methods like resonance ionization laser ion sources or surface ionization. The ions are then extracted, formed into a beam, and sent through a high-resolution separator magnet for mass selection. Selected beams can be delivered to over sixty experimental stations for low-energy studies or further accelerated by the HIE-ISOLDE linear accelerator to energies of several MeV per nucleon for reaction experiments.

Collaborations and impact

ISOLDE functions as a major international user facility, hosting hundreds of scientists from institutions worldwide under the ISOLDE Collaboration. It maintains strong ties with other radioactive beam facilities like TRIUMF in Canada, RIKEN in Japan, and the Facility for Rare Isotope Beams in the United States. The research has direct impact on adjacent fields, providing crucial nuclear data for the ITER fusion project and advancing nuclear medicine. The facility's pioneering techniques in isotope separation and laser ionization have influenced the design of next-generation installations, cementing its legacy as a cornerstone of modern nuclear physics and a vital component of the European research infrastructure at CERN.

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