Archives of Synchro-Cyclotron Division, SC

Identity Statement [Top]

Reference code(s)



Archives of Synchro-Cyclotron Division, SC


1952 - 1991

Level of description


Extent of the unit of description

231 boxes, 25 linear metres

Context [Top]

Name of creator

Synchro-Cyclotron Division

Administrative history

In December 1951, at a UNESCO meeting in Paris (concerning the proposed new European Organization for Nuclear Research), the Synchro-Cyclotron was described as an ideal solution for a medium-energy accelerator. The reasons given were that it would be relatively easy and fast to build and not too costly, and was primarily intended to bridge the gap until the 28 GeV Proton Synchrotron would be ready in the early 60s.

In 1952 Professor C. Bakker (Director-General of CERN from 1955 to 1960) became Leader of the group responsible for the designing and construction of the CERN Synchro-Cyclotron (SC), and later became the Director of SC Division on a part-time basis.

In 1955 Professor W. Gentner took up the appointment as Director of SC Division.

In 1960 the SC Division become the Synchro-Cyclotron Machine Division (MSC), directed by P. Lapostolle. It was responsible for operation, maintenance, modification and development of the machine.

In 1964 G. Brianti became Leader of the MSC Division.

In 1966 new departments which remained until 1976, were formed by regrouping the existing divisions. MSC Division was integrated into the Physics I Department.

In 1968 E. G. Michaelis became the new leader of MSC Division until end 1975.

In 1971 following approval for the construction of a second Laboratory adjoining the existing site, divisions were divided between two administrative units, Laboratory I and Laboratory II. MSC Division remained part of the Physics I Department of Laboratory I.

In 1976 the two CERN Laboratories were united and the MSC and MPS (Machine Proton Synchrotron) were amalgamated to form the Proton Synchrotron (PS) Division. The two new PS groups, Cyclotron Development (CD) and Cyclotron Operation (COP), came from MSC Division.

In 1982 the CD and COP groups were merged to create the Syncho-Cyclotron Group (still part of the PS Division), which existed until 1990.

Immediate source of acquisition or transfer

Allardyce, Brian W, PS-SC Group Leader from 1984 to 1990

Content & Structure [Top]

Scope and content

This collection contains various documents, reports, notes, memoranda, specifications, correspondence, plans, minutes concerning the Synchro-Cyclotron.

The design of the original Synchro-cyclotron machine with a circumference of 15.7 metres started in 1953, before CERN came into existence. Building and construction for the machine began in 1954 on the site at Meyrin and the objective was an accelerator to give protons of 600 MeV energy with an average beam intensity of 1mA. This was achieved in August 1957 and the experimental programme began in April 1958. One of the first achievements was the long-awaited observation of the decay of a pion into an electron and a neutrino. The SC remained in regular operation with a beam current that rose progressively from 0.3 to just over 1mA.

Emphasis swung to nuclear physics in the mid-1960s with the construction of an Isotope Separator on-line Detector, ISOLDE. A vast range of short-lived nuclei became available for study at this facility, which attracted hundreds of nuclear physicists to participate in the experimental programme. The SC was adapted to provide beams for ISOLDE, and it received its first beam in October 1967.

In 1969 preparations began to modify the SC machine with the aim of increasing its mean beam intensity and improving the efficiency at which the circulation beam could be extracted from the machine. The original SC was shut down in June 1973 for these modifications to be carried out and it started up again for physics research in January 1975.

The performance of the reconstructed SC machine, or SC2, was greatly improved. The internal beam current was increased from 1mA to a peak of about 4mA.

In 1990 the decision to shut down the SC followed the realisation that much of the accelerator's research programme could continue at the Booster of CERN's Proton Synchrotron accelerator (PS).

Appraisal, destruction and scheduling information

Nothing was destroyed.


No further accruals are expected.

System of arrangement

The original order has been preserved.

Conditions of access and use [Top]

Conditions governing access

See file level description and the CERN operational circular No 3: rules applicable to archival material and archiving at CERN. In general, records on any subject that are over 30 years old, and all records of a purely scientific nature, may be consulted.

Conditions governing reproduction

Copyright is retained by CERN, no reproduction without permission.

Language / scripts of material

Most of the material is written in English or French, with a few files in German.

Finding aids

Listed to file level in the CERN Archives Database.

Description control [Top]

Archivist's note

Description prepared by Sandrine Reyes.

Date(s) of description

Geneva, the 10th April 2002, Revised 2007.