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Chapters:
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MuSR /
LambdaFits< The field distribution probed by muons | Index | Origin of the muon diamagnetic shift > The standard powder calibration is as follows: The muon powder spectra are fitted to a Gaussian decay {$ e^{-\sigma_\mu^2t^2/2} $} The reference papers (Brandt Phys Rev B 37 2349 (1988) and Barford and Gunn, Physica C 156, 515 (1988)) quote a value for the sums over the reciprocal lattice vectors of the flux lattice such that {$ \overline{\Delta B^2} = 3.71\cdot 10^{-3} {{\phi_0^2} \over {\lambda^4}} $} which holds for both SI and CGS systems. With {$ \phi_0=2.07\cdot 10^{-15}$} T/m2, {$\sigma_\mu= 2\pi\gamma_\mu \sqrt{\overline{\Delta B^2}}$}, and considering that the powder average for large anisotropy ({$m_{ab}/m_c\ge 9$}) provides an effective London penetration (Barford and Gunn, Physica C 156, 515 (1988)): {$ \lambda_{eff}=1.23\lambda_{ab}$} one finally gets {$ \sigma_\mu [\mu s^{-1}] = {{2\pi\cdot 1.355\, \sqrt{0.371}\cdot 2.07}\over{(1.23)^2}}\,10^{-6+8-1-15+18}\, {1 \over (\lambda_{ab} [nm])^2} = {{7.086 \cdot 10^4 }\over(\lambda_{ab} [nm])^2}$} This formula, used in our papers, agrees completely with Bernhard et al. Phys Rev. Lett. 86 1614 (2001) It does not agree with that of Y.J. Uemura et al. Nature 364 605 (1993) and Russo et al., Phys. Rev. B 75 054511, whose powder muon width {$\sigma_\mu$} are always a factor 0.7 smaller. < The field distribution probed by muons | Index | Origin of the muon diamagnetic shift > |