Muon spectroscopy
Muon Spectroscopy provides a probe of materials at an atomic level.
The ISIS Muon Group operates six muon spectrometers for condensed matter and molecular studies using both positive and negative muons. These spectrometers are used by researchers from around the world for a wide range of studies that include investigations in the areas of magnetism, superconductivity, charge transport, molecular and chemical studies, modelling hydrogen behaviour in, for example, semiconductors or proton conductors, and elemental analysis.
The instrumentation operated by this group is currently undergoing an exciting period of development, with plans for new and state-of-the-art instruments (for both positive and negative muon studies). The group is also developing novel calculation methods, such as density functional theory (DFT) techniques, to help with the understanding of experiment results.
Click here to read the online version of our muon spectroscopy brochure.
Muon instrument comparison
Comparison table showing the various features of the ISIS muon instruments.
| Instrument: | Emu | HiFi | MuSR | Argus |
|---|---|---|---|---|
| Muon beam | Surface positive muons (p=27±1 MeV/c, E=3.2 MeV). Polarisation > 99%. | Surface positive muons (p=27±1 MeV/c, E=3.2 MeV). Polarisation > 99%. | Surface positive muons (p=27±1 MeV/c, E=3.2 MeV). Polarisation > 99%. | Positive surface muons, also positive or negative decay muons. |
| Range (1) | ~160 mg/cm2, spread 50 mg/cm2 | ~160 mg/cm2, spread 50 mg/cm2 | ~160 mg/cm2, spread 50 mg/cm2 | Surface muons: Mean range 100 mg/cm2, spread 50 mg/cm2 |
| Pulse structure | Single pulse (70 ns FWHM), repetition rate 50 Hz (with 1 of 5 repetitions missing) | Single pulse (70 ns FWHM), repetition rate 50 Hz (with 1 of 5 repetitions missing) | Single pulse (70 ns FWHM), repetition rate 50 Hz (with 1 of 5 repetitions missing) | Single or double pulse (70 ns FWHM, separation 324 ns), repetition rate 50 Hz (with 1 of 5 repetitions missing) |
| Full Ag asymmetry> | 28% | 28% | 28% | |
| Frequency response | Up to 10 MHz for relaxation/rotation limited by the pulse width. RF and laser experiments can allow up to 500 MHz. | Up to 10 MHz for relaxation/rotation limited by the pulse width. RF and laser experiments can allow up to 500 MHz. | Up to 10 MHz for relaxation/rotation limited by the pulse width. RF and laser experiments can allow up to 500 MHz. | Up to 10 MHz for relaxation/rotation limited by the pulse width. RF and laser experiments can allow up to 500 MHz. |
| Spot size (mm) (H,V) | 10-30, 10 | 10-30, 10 | 10-30, 10 | 10-50, 10-50 |
| Detectors | 96 | 64 | 64 | 192 |
| Typical count rate (MEv/h) | 40 to 200 MeV/hour (depending on slit setting and degraders) | 40 to 200 MeV/hour (depending on slit setting and degraders) | 40 to 200 MeV/hour (depending on slit setting and degraders) | 55 |
| Background | 1 in 106 of the peak rate background and muon count rates equal at ~25 µs. | 1 in 106 of the peak rate background and muon count rates equal at ~25 µs. | 1 in 106 of the peak rate background and muon count rates equal at ~25 µs. |
| Instrument: | Emu | HiFi | MuSR | Argus |
|---|---|---|---|---|
| Zero field | <0.01 G | <0.1 G | <0.01 G | |
| Longitudinal field | 5000 G | 50000 G | 2500 G | 3950 G |
| Transverse field | 100 G | 100 G | 600 G | 200 G |
| Instrument: | Emu | HiFi | MuSR | Argus |
|---|---|---|---|---|
| Dilution fridge | 30 mK-300 K | 30 mK-300 K | Y | Y |
| He3 cryostat | 0.35-50 K | 0.35-50 K | 0.35-300 K | |
| He4 cryostat | 1.5-300 K | 1.5-300 K | 1.5-300 K | 1.5-300 K |
| Flow cryostat | 5-300 K | 3-400 K | 3-600 K | 10-300 K |
| CCR | 12-600 K
CCR low limit: 12 K -> 10 K | 10-600 K | N | |
| Furnace | 300-1500 K | 300-1500 K | 300-1000 K | Y |
| Gas handling | Y | Y | Y | N |
| Liquid handling | Y | Y | Y | N |
| Radio frequency | Y | Y | Y | Y |
| Pressure | <50 bar | <50 bar | N | 0.6 kBar |
| Laser stimulation | N | Y | N | Y |
