Deva

This instrument is decommissioned .

Deva preparation

Roger Lichti (Texas Tech University) preparing a flow cryostat on DEVA for studies of semiconductors using the RF-mSR technique.
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Muon instrument Deva

Deva was a partly scheduled instrument, equipped with a dedicated spectrometer for studies using the radio-frequency mSR technique. It was also used for developing new techniques, and for more specialised experiments.

The RF-mSR technique has seen significant development at ISIS over recent years. It involves stimulation of sample nuclei or the implanted muons by radio frequency pulses, and is ideally suited to a pulsed source such as ISIS since the RF can be timed to coincide with muon arrival. This means that sample heating is negligible; it also means that processes involving a muon state change can be followed by varying the time of the RF with respect to muon arrival. Multi-pulse techniques, similar to those used in NMR, also benefit from the long time window available at a pulsed source. For some samples, RF-mSR can be used to extend significantly the observable precession frequency from its normal ISIS limit of around 10 MHz up to many hundreds of MHz. In other samples, excitation of sample nuclei can decouple them from the muons, simplifying analysis. Further details of RF-mSR can be found in ‘The commissioning of a spectrometer optimised for radio-frequency measurements at a pulsed muon source’, SP Cottrell et al., Physica B 289 (2000) 693.

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