EMU is a 32-detector µSR spectrometer
which is optimised for zero field and longitudinal field measurements.
Fields of up to 4000 G can be applied, and sample temperatures in the
range of 350mK to 1000K can be produced using a variety of sample
environment equipment.
| Production target | 5, 7, or 10 mm graphite at 45o to proton beam |
| Beam | positive muons, at or near surface momentum |
| Incident momentum | 26.5 MeV/c, 10% momentum bite |
| Pulse structure | single pulse, 80 ns fwhm |
| Contamination | e+ /µ+ < 0.15 with separator voltage > 70kV |
| Beam size at focus | Vertical: 10 mm fwhm, horizontal: adjustable, 10-27 mm fwhm |
| Intensity | 4x105 µ+ /s shared by the three south-side muon areas |
| Data rate | event rates of typically 10-20 million events per hour (5 mm muon production target, ISIS current of 180 µA |
| Muon polarisation | 100% |
| Muon energy; range | 3.2 MeV; range approx. 100 mg.cm-2 for surface momentum |
| Background | histograms contain a constant background of approx. 10-5 times the number of counts in the first bins |
| Instrument geometry | longitudinal (LF) or zero (ZF) applied magnetic fields, low transverse fields (TF) |
| Detectors | 32 scintillator segments in two circular arrays. Grouped 2x16 for ZF, LF |
| Sample environment | - Helmholtz coils (0-400 mT), LF or TF,
- calibration coils (0-10 mT) TF
- zero field compensation to <3 µT
- sorption crysotat (350 mK - 50 K)
- Oxford instruments cryostat (2 K - 300 K)
- closed cycle refrigerator (CCR) (12 K - 340 K)
- furnace (300 K - 1000 K)
|
| Data acquisition | Instrument controlled by a VAXstation 3200 |
| Timing resolution | 32 TDCs with time resolution settings of 8, 16, 24, or 32 ns |
| Measurable frequencies | 0.1-10 MHz (upper limit due to finite muon pulse width) |
Emu Sample Environment
So that you can check the sample environment equipment that you have been assigned, the following ‘codes’ are used to denote the various cryostats, etc, on the schedules you have received.
Schedule Code | Equipment | Details |
SR/MUSR | Sorption cryostat | 350 mK – 50 K |
CCR | Closed cycle refrigerator | 12 K – 600 K |
Fur/Mu | Furnace | 300 K – 1000 K |
GH/EMU | Gas Handling | NA |
LH/EMU | Liquid Handling | NA |
RFL/EMU | Reflector furnace | 300 K – 1500 K |
RF | Radio Frequency | NA |
