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Dispense


µSR

Chapters:

  1. Introduction
  2. The muon
  3. Muon production
  4. Spin polarization
  5. Detect the µ spin
  6. Implantation
  7. Paramagnetic species
  8. A special case: a muon with few nuclei
  9. Magnetic materials
  10. Relaxation functions
  11. Superconductors
  12. Mujpy
  13. Mulab
  14. Musite?
  15. More details

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HowToDetectMuonium

< Muonium detailed calculation | Index | Precession in the radical state >


The intention of this page is eminently practical and it is related to nearly free muonium, as it may be observed in e.g.

  • Intrinsic silicon (the metastable antibond muonium state, with hyperfine frequency nearly half of that of muonium in vacuum)
  • Endohedral Mu@C60: muonium trapped inside the cage of a C60 molecule.
  • Muonium in saturated solvents, e.g in water (ultrapure, O2 removed for its paramagnetic moment that produces fast depolarization).

A direct, difficult way to observe this species is by means of a very high resolution spectrometer, in zero external field, looking for the direct hyperfine transition at {$\nu_0$}.

Another way to detect a spectroscopic signature of muonium is in weak transverse fields, with moderate time resolution. Whereas the triplet-singlet transitions {$\nu_{13},\nu_{34}$} (Eq. 3, previous page) are always larger than {$\nu_0$}, the triplet precession frequencies {$\nu_{12},\nu_{24}$} in moderate fields are much smaller:

{$ \begin{eqnarray}\nu_{12} &=& \frac {\nu_0} 4 +\nu_-\,+\frac {\nu_0} 4 \left(1-2\sqrt{1+\frac {\nu_+^2} {\nu_0^2}}\right) \,\approx\, \nu_-\, -\, \frac {\nu_+^2}{4\nu_0}\\ \nu_{24} &=& -\frac {\nu_0} 4 +\nu_-\,-\frac {\nu_0} 4 \left(1-2\sqrt{1+\frac {\nu_+^2} {\nu_0^2}}\right) \,\approx\, \nu_-\, +\, \frac {\nu_+^2}{4\nu_0} \end{eqnarray}$}

and of comparable amplitudes {$\approx 1/4$} for very low fields, below 10-15mT (the exact amplitudes are the factors {$c,s$} respectively from the (previous page). In practice weak transverse field muonium appears as a doublet centered at {$ \frac {\gamma_e-\gamma_\mu} 2 B$}, i.e. shifting with field at a rate of 1.4 MHz/G.


< Muonium detailed calculation | Index | Precession in the radical state >

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Page last modified on August 25, 2009, at 09:10 AM