User login


A CMMS spectrometer is a magnet (or magnets) plus an array of counters to detect incoming muons and decay positrons. The magnets are of various types - Helmholtz, solenoid, or solid pole electromagnet; superconducting or not. In fact, most spectrometers have more than one magnet. The main magnet of an apparatus is usually oriented so the field is along the beam axis (z direction) which allows surface muons to enter the sample without being turned away. Other coils provide weaker fields in perpendicular directions either for zeroing the field or for applying weak fields (<10 mT) transverse (x,y directions) to the beam direction. Most of the counter systems are movable in various ways, and many follow a uniform standard design of multi-counter modules mounted on tracks on tables attached to the spectrometer. Some counter arrangements are partially built into the sample inserts. These are the low background apparatuses for small or thin samples which have veto counters to reject counts from anything but the sample itself. All apparatuses rest, and roll, on standardized rails so they can be reproducibly positioned in any beamline. They can be rolled back from the beam snout (to access collimators etc) at any time and accurately rolled back into position by one person. The four beam lines, M15, M20, M9B and M13 which are used for µSR have such rail systems. enter the text here

Spectrometersort descending Magnet type Field strength/orientation Field calibration Counter acceptance Experiment types Equipment image Maintenance History
Belle Superconducting Helmholtz 7.5 T / z 0.0747 T/A 4 p HTF
DR(Pandora) Superconducting Helmholtz 5 T / z, 5 mT / x, y 0.0617 T/A 0.1-1.5 p LF, TF, ZF, HTF
Gas Cart LF/TF Helmholtz 33 mT / z, y TF, LTF, Z TF, LTF, Z
Helios Superconducting solenoid 7 T / z, and 2 mT / x 0.096233 T/A 1-3 p LF, TF, HTF, RF-microwave
High-Time - Decommissioned in 2015 Superconducting Solenoid 7.0 T / z 0.09068 T/A 4 p HTF
LAMPF 3 x Helmholtz 0.3 T / z (0.39 T on M15), and 10 mT / x, y 0.0004 T/A (4 G/A) 4 p LF, TF, LTF, ZF, RF-microwave
M9A 3T Magnet Superconducting Helmholtz
Omni - Decommissioned in 2012 3 x Helmholtz 0.3 T / z, and 20 mT / x, y 0.0004 T/A (4 G/A) 4 p LF, TF, LTF, ZF, RF-microwave
Omni-Prime 2 x Helmholtz, 1 x Saddle 0.3 T / z, 20 mT / x, 20 mT / y 0.000425 T/A (4.25 G/A) z 0.0000341 T/A (0.341 G/A) x 4 π LF, TF, LTF, ZF, RF-microwave
SFUMU LF/TF Helmholtz 0.45 T / z, y 0.0006 T/A (6 G/A) 3 p
Varian Magnet- Decommissioned Solid Pole Electromagnet 1 T / x 1-2 p TF with high momentum muons