Archives of Muon g-2 experiment

Identity Statement [Top]

Reference code(s)

CERN-ARCH-Muong-2-01 to CERN-ARCH-Muong-2-12


Archives of Muon g-2 experiment


October 1959 to August 1989

Level of description

Sub-fonds level

Extent of the unit of description

12 items, 6 boxes, 1linear metre

Context [Top]

Name of creator

Muon g-2 Collaboration

Administrative history

In 1959 CERN launched the g-2 experiment aimed at measuring the anomalous magnetic moment of the muon. The measures were studied using a magnet 83cm x 52cm x 10cm borrowed from the University of Liverpool. The experiment's aim was to test quantum electrodynamics, a theory elaborated in the 1940s to describe the effect of the electromagnetic force on charged subatomic particles such as electrons or muons. Among other things, it predicted an anomalously high value, slightly above 2, for the muon's magnetic moment 'g', hence the name of the experiment.

In 1960 a magnet 6 metres in length was set up in the experimental hall of the Synchro-Cyclotron in order to make measurements more precise.

In 1961 the first direct measurements of g-2 was published with a precision of 2% with respect to the theoretical value.

In 1962 this precision had been whittled down to just 0.4%.

In 1966 a second g-2 experiment, directed by Emilio Picasso (Nuclear Physics Divisional Leader from 1972 to 1975) was set-up on the Proton-Synchrotron (PS) accelerator. Its result was 25 times more precise than previous results. The experiment revealed a quantitative discrepancy with the theory and thus prompted theorists to recalculate their predictions.

In 1969 a new study of the g-2 experiment started.

In 1974 this third experiment was installed in the South-East hall of the SPS. The apparatus included a 14 m diameter storage ring and a focusing system with electrostatic quadrupole field. The final results were published in 1979 and confirmed the theory to a precision of 0.0007%.

In 1984 the United States took up the mantle of investigating the muon's anomalous magnetic moment in Brookhaven National Laboratory.

* Source : Infinitely CERN, Memories from fifty years of research, Presscutting-60-020, Annual reports 1959, to 1969, CERN Courier April 2001, CERN-LEP-DI-89-42

Immediate source of acquisition or transfer

Received from Emilio Picasso, Divisional Leader of Nuclear Physics Division from 1972 to 1977

Content & Structure [Top]

Scope and content

This collection contains internal reports from the Nuclear Physics Division on the muon g-2 experiment from the year 1959 to 1977. It also contains external reports from 1984 to 1987, books on calibration data, run data from 1964 to 1968, books on calibration, run data from 1965 to 1971.

Appraisal, destruction and scheduling information

Nothing was destroyed.


No further accruals are expected.

System of arrangement

The original order has been preserved. There was no classification plan, but the documents were classified by chronological order.

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.

Finding aids

Listed to file level in the CERN Archives Database.

Description control [Top]

Archivist's note

Description prepared by Florent Perret.

Date(s) of description

Geneva, the 23rd June 2004, Revised 2007.