MUON BEAMS & µSR FACILITIES

Muon beams of high luminosity (appropriate for µSR ) are available at several "Meson Factories" around the world.

Principal CW Muon Facilities

Those produced by the cyclotrons at

The µSR Facility at PSI (the Paul Scherrer Institut, near Zürich, Switzerland) and
our Facility at TRIUMF (the TRI-University Meson Facility in Vancouver, Canada)

produce continuous beams and are superior for time-differential µSR experiments requiring high time resolution.

Pulsed Muon Facilities

Others at the following labs produce pulsed beams and are superior for long time range experiments and those involving irradiation of the target with RF or laser power during the muons' short lifetime (on average 2.2 µs).

The µSR Facility of ISIS at the Rutherford Appleton Lab in the U.K. and the associated RIKEN/RAL Muon Facility offer the highest intensity in 2001.
The BOOM (BOOster Muon) facility of the KEK laboratory in Japan and the associated Meson Science Lab will in the next few years be superceded by the JAERI JHF accelerator centre in Tokai.

Other Accelerator Labs with Muon Capabilities

The high-intensity µSR facility at the Clinton P. Anderson Meson Physics Facility (LAMPF) was just beginning to find its optimal use when the facility was shut down. There was hope for utilizing this world's brightest muon source for µSR experiments if the proposed Pulsed Lepton Facility had been built for the Proton Storage Ring, in which case LAMPF would have become a pulsed muon facility.
There are also µSR facilities at the JINR lab in Dubna (Russia) but their future is uncertain.
In principle, any high-intensity hadron accelerator of greater than about 400 MeV incident kinetic energy should be capable of producing useful muon beams. A list of the world's accelerators, organized into various categories, is maintained at LAMPF.
The time structure of the beam should be either CW or very sharply pulsed (pulse widths as short as possible, but no greater than about 100 ns, with at least 20 µs between pulses) to produce the best results, but time-integral methods can make use of any muon beams.

Editorial comment by Jess Brewer :

The main impediment to expanded use of µSR is political: the high energy physics community that is usually responsible for the construction of large accelerators is not always enthusiastic about sharing their resources with the materials scientists who make up the bulk of the µSR user community; meanwhile, the materials science community rarely regards large accelerators as valuable resources. Both communities suffer when they ignore the opportunity for cooperative alliance offered by µSR and continue to see each other as adversaries. There are a few hopeful signs of enlightened self-interest in this decades-old struggle, but the tradition of animosity between narrow interest groups is still the worst enemy of cooperative scientific inquiry.

Jess H. Brewer

Last modified: Sat Aug 4 17:39:33 PDT 2001