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Adrian Hillier of the ISIS Muon Group by the MuSR muon spectrometer

The MuSR muon spectrometer at ISIS, used for studies in a wide variety of condensed matter and molecular science areas
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In addition to neutron production, ISIS is the world's most intense source of pulsed muons for condensed matter research.

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Details of all ISIS sample environment equipment can be found HERE

Positive Spin - Muon Group Newsletter (April 2014) 

Muon Xpress service, for initial sample characterisation and feasibility checks

Muon instrument schedules: visit the individual instrument pages and click on the 'Schedule' link

Details can be found here of European funding for researchers from EC countries wishing to use ISIS muons.

 

The muon instruments MuSR, EMU, ARGUS and HiFi run a very diverse science programme, using implanted positive muons both as magnetic probes, in magnetism, superconductivity and charge transport, and as proton analogues in chemical physics, including investigations of hydrogen behaviour in semiconductors, molecular dynamics and light particle diffusion. 

Spin-polarised muons are generated at ISIS by collisions between the proton beam and a thin carbon target. For condensed matter studies, positive muons are implanted into materials and the time-evolution of the muon polarisation is observed. Highlights of work using ISIS muons include the discovery of shallow donor hydrogen states in semiconductors; characterisation of correlations in spin-glass materials and investigation of spin dynamics in frustrated systems; charge-carrier motion studies in conducting polymers; characterisation of flux line lattice behaviour in organic superconductors; study of the interplay between magnetism and superconductivity in high-temperature superconductors; and investigation of quantum tunnelling of light particles.

Muons can be used to study a wide variety of magnetic systems, with the muon acting as a microscopic magnetometer and probing longer fluctuation timescales compared with neutron scattering. Muons are suitable for studies of small-moment, short-range, random, or dilute magnetism. In superconducting materials, muons can be used to explore the flux-line lattice generated when a field is applied to a type-II material, complementing small-angle neutron scattering measurements in some cases. Muons can be used to determine fundamental superconducting parameters such as the penetration depth, coherence length, superconducting carrier density and effective mass. They can also be used to study various charge transport phenomena, including ion mobility in battery cathode materials, electron dynamics or charge carrier motion in conducting polymers.

The positive muon can act like a light proton. Where proton or hydrogen atom behaviour is difficult or impossible to study directly, observation of the muon response can enable models of its heavier counterpart to be produced; examples include investigation of hydrogen behaviour in semiconductors. In molecular materials, muons can form radical states sensitive to molecular dynamics, and can be used to study chemical reactions. 

The RIKEN-RAL muon facility supports a wide range of muon investigations. In addition to condensed matter studies, there is ongoing work into the physics of muon catalysed fusion, which occurs in deuterium-tritium mixtures when negative muons take the place of electrons in the hydrogen atom isotopes. There are also experiments using negative muons to measure nuclear charge distributions, together with development of low-energy muon beams.

Expertise

Muon group members have a wide variety of expertise in condensed matter, molecular and chemical systems and the use of the muon technique to provide atomic-level information in these areas.  Specific examples include studies of organic and inorganic magnetism, modeling hydrogen behaviour in semiconductors, free-radical chemistry, ionic conduction, high temperature superconductivity (including atomic-level investigations and flux-line lattice studies), and muon technique development including a variety of pulsed environments for muon experiments.

Funding / grant information

The muon group has a variety of additional funding sources, principally to allow user access to the facility or develop facility equipment for the user community.  These include:

- European Access grants to allow EC researchers to use the facility

- Technology development grants from the EC to develop the muon technique, in collaboration with the PSI muon facility in Switzerland and university partners

- Facility development grants (including, at present, a large grant to build a new high-field muon spectrometer)

Individual group members also have grants to support their own research programmes

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