| Home > Multimedia & Outreach > Experiments at CERN > Formation and Interaction of Muonium in Insulators and Semiconductors |
| Experiments at CERN | |
| Title | Formation and Interaction of Muonium in Insulators and Semiconductors |
| Experiment | SC81 |
| Greybook | See SC81 experiment |
| Approved | 18 January 1979 |
| Status | Finished |
| Collaboration | MUSR |
| Accelerator | SC |
| Abstract | newline Semi-conductors Many muon spin rotation experiments have been performed on Si and Ge. Two types of muonium atoms have been detected at temperatures between LNT and 20$^0$K: a) Deep-donor type with fully spheric symmetry. ; Measurements at very low temperature (60mK-20K) have given important information on the dynamics of these two centres. Measurements will also be made on GaAs which is very similar to Si and Ge, both in lattice structure and in energy gap. However both elements in these compounds have strong nuclear magnetic moments that smear out the hyperfine transitions detected by $\mu$SR in a transverse field. So the investigation on muonium formation in this material has to be made in longitudinal fields. Its dependence on doping will be studied on a large range of concentration, using samples grown at Parma University. \newline Insulators Muonium is believed to be present in most insulators and its formation can be proven by longitudinal field 'quenching' experiments, as in the case of most semi-conductors. Furthermore muonium dynamics at different temperatures can be studied in transverse field experiments. In magnetic insulators, however, while the muonium precession is very often hidden by magnetic perturbations, very interesting information is yielded by the diamagnetic fraction of muons, precessing at the Larmor frequency. Experiments on $ MnF _{2} $ single crystals, which constitute a very well known test case for antiferromagnetic insulators, have shown that the muon is sensitive to the critical behaviour of the electron spin fluctuations. The muon localization as well as the fluctuation component at $ K = K _{f} $ and the frequency shift have been deduced. The same technique will be applied to a vast category of magnetic materials of the family of the fluorides and oxides. \newline Equipment For transversal field experiments the set-up in use by the SC65 will be used. For longitudinal measurements an alternative set-up will be used as shown. The wire chamber spectrometer has proven very useful in the experiments on antiferromagnetic insulators, where the discrimination between muons stopped in the sample and those stopped in the cryostat wall is very critical. |
| Related document(s) | CERN-PSCC-78-22 (PSCC-P-4) CERN-PSCC-79-48 (PSCC-M-37) CERN-PSCC-79-52 (PSCC-M-40) CERN-PSCC-79-53 (PSCC-M-41) CERN-PSCC-80-125 (PSCC-M-69) CERN-PSCC-81-16 (PSCC-M-78) CERN-PSCC-82-23 (PSCC-M-105) CERN-PSCC-83-48 (PSCC-M-169) CERN-PSCC-83-50 (PSCC-M-171) CERN-PSCC-85-77 (PSCC-M-248) CERN-PSCC-86-13 (PSCC-M-254) CERN-PSCC-86-11 (PSCC-M-253) |