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Atomic capture of negative muons in oxides

University of British Columbia

Using the lifetime technique, atomic capture ratios of negative muons have been measured in 41 oxides. The experimental method was to detect the decay electrons and to use the unique lifetime signature to identify the element which captured the muon. Muons were produced via the backward decay of pions which were provided by the M20 channel at TRIUMF. The experimental set-up and electronic logic were tested against the positive muon lifetime which was measured to be 2197.7 ± 2.6 ns, in good agreement with the present world average of 2197.138 ± 0.065 ns. The results, though somewhat different from the earlier TRIUMF findings, are consistent with the mesic x-ray measurements. We have also carried out new measurements for MnO, Fe₃O₄, Coo, NiO, NbO, MoO₂, SnO, PrO₂, HgO and Pb₃O₄. It has been noticed that the atomic capture ratios have a linear dependence on the density, whereas the Z-dependence is periodic. Using our results and data from the literature, we have been able to obtain an empirical formula for the atomic capture ratios in oxides, chlorides and fluorides. Our results for oxides, also show evidence for the existence of chemical and/or solid state effects in the atomic capture process. The lifetimes of negative muons bound in heavy nuclei were also measured during this experiment. Our results are in good agreement with the earlier measurements carried out at TRIUMF.

Text

2010-05-16

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http://hdl.handle.net/2429/24776

Physics

University of British Columbia

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