Muon Beams at the Paul Scherrer Institute
| µE1
| µE4
| piM3
| piE1
| piE3
| piE5
|
Intense beams of positively or negatively charged, spin-polarised muons are available
at the
PSI Accelerator
Facilities
in the experimental areas µE1, µE4, piM3, piE1, piE3, and piE5.
Areas with "M" in their name are connected to target station M
(thin target, 5 mm of graphite), those with "E" to station E (thick target,
60 mm or 40 mm of graphite). The muons originate
from the decay of pions produced by the interaction of the
1.8 mA,
590 MeV proton beam with the nuclei of the target material.
The µE1 beam line is equipped with a
superconducting decay channel, providing beams of positive
or negative muons
with useful momentum ranges 40-125 MeV/c.
The µE4 beam line has been completely dismantled. In its place, a
new, large acceptance beam line for muons with low momentum
(< 40 MeV/c) is under construction.
The piM3, piE1, piE3, and piE5 beam lines are designed for
- Positive or negative pions,
- Positive muons emerging from the production targets:
"surface" (1) and "sub-surface muons" (2)
(momentum range 5-30 MeV/c), and
- Positive or negative "cloud muons" (3) (momentum 10-280 MeV/c).
| (1) | Surface muons originate from pions stopped close to
the surface of the target. They have kinetic energies around 4.1 MeV
(momentum 28 MeV/c). |
| (2) | Sub-surface muons originate from pions stopped
in the bulk of the target, thus losing some energy on their way to the
surface. |
| (3) | Cloud muons originate from pions decaying
outside the target. |
The piM3 beam line is entirely dedicated to the
µSR User Facilities since 1991. It is equipped with a spin
rotator and - since 1998 - a fast-switching electrostatic "kicker".
The surface-muon beam can be shared or switched ("muons on request",
MORE) between the
GPS and
LTF
Facility Instruments.
The µE1, µE4, piE1 and piE3 beams are shared between µSR
(GPD,
DOLLY,
ALC, and
other µSR
spectrometers)
and particle-physics experiments to varying degrees (see
µSR beam-time
schedules).
Only the piE5 beam is currently not used for µSR experiments.
|
