ISOLDE

The On-Line Isotope Mass Separator, also known as the ISOLDE Radioactive Ion Beam Facility, is a facility located at CERN on the PS Booster. It started operating in 1967 and upgraded several times. With a lifetime more than a half-century, it's the home of the longest living experiment of CERN. The facility is dedicated to producing radioactive nuclei for a number of applications covering nuclear, atomic, molecular and solid-state physics, but also biophysics and astrophysics. The large variety of available final species allows the systematic study of atomic and nuclear properties and exotic decays far from the line of stability. The facility is operated by the ISOLDE Collaboration comprising CERN and nine European countries. As of 2006, more than 60 physics experiments are active there.

Radioactive nuclei are produced at ISOLDE by impinging a high energy beam of protons on a stationary target. Several target materials are depending on the desired final species. Collisions between the proton beam and the target produce a variety of fragments, which are extracted and filtered to yield the desired isotope. The time required for extraction places a lower limit on the half-life of isotopes which can be produced by this method. Once extracted, the isotopes are directed either to one of several detectors, an isotope harvesting area or the REX accelerator for acceleration to higher energies.

One of the major experiments in ISOLDE is the Miniball-setup. An upgrade of the post-acceleration system is currently on-going, ready to produce energetic Radioactive-Ion Beams (RIBs) of up to 10 MeV per nucleon in 2018.

History

Excavation of underground experimental area for ISOLDE

In 1950, two Danish physicists Otto Kofoed-Hansen and Karl-Ove Nielsen discovered an on-line technique for producing radioisotopes (i.e. radioactive nuclei) which enabled producing isotopes with shorter half-lives than earlier methods. Ten years later, in Vienna, at a symposium about separating radioisotopes, plans for an isotope separator were published. Using these plans, CERN's Nuclear Chemistry Group (NCG) built a separator and tried it on the Synchro-Cyclotron. The high success rate obtained implied that the Synchro-Cyclotron was an appropriate machine for on-line rare isotope production. In 1964, a proposal for an isotope separator project accepted by the CERN Director-General and ISOLDE project began.

The "Finance Committee" for the project set up with five members, then extended to 12. As the term "Finance Committee" had other connotations, it was decided 'until a better name was found' to call the project ISOLDE and the committee the ISOLDE Committee. On May 1966, the Synchro-Cyclotron shut down for some major modifications. One of these modifications was the construction of a new tunnel to send proton beams to a future underground hall that would be dedicated to ISOLDE. In 1965, as the underground hall at CERN was being excavated, the isotope separator for ISOLDE was being constructed in Aarhus. Separator construction made good progress in 1966 and the underground hall was finished in 1967. On 16 October, the first experiment carried out and successful results, like identification of some new isotopes for several elements, were started to be achieved.

Further reading

• "ISOLDE – a laboratory portrait". Hyperfine Interactions. 129 (1–4). December 2000. doi:10.1023/A:1012690327194. Retrieved 9 August 2019.

External links

• ISOLDE - official website
• ISOLDE page within CERN website

See also

• Eurisol
• Total absorption spectroscopy
• Facility for Rare Isotope Beams
• Rare Isotope Science Project