Larmor precession method

The muonic helium atom was first discovered at SREL by means of the Larmor precession method Because of the very complicated formation process the residual polarisation of the muons in neutral muonic helium could not be predicted very well The y s are captured by the helium atom, and the atom looses both electrons due to Auger effect The He y" ion is highly excited (n=il4) The deexcitation is very fast and after a short time the ion is in its ground state The binding energy for electrons is like in... 

It is appropriate here to provide only brief details of the principles behind MRI methods. An excellent book on the subject, particularly with regard to porous media, is that of Callaghan. Nuclear spins in a magnetic field gradient G will have different Larmor precession frequencies depending on their spatial location. Thus, during a field gradient, the local Larmor frequency will be... 

It is important to note that in the context of relaxation studies a combination of Mossbauer spectroscopy and the PAC and pSR methods allows a given problem to be approached over a range of experimental timescales. For example, it may be recalled that the experimental timescales in Mossbauer spectroscopy are the lifetime of the excited state of the nucleus and the Larmor precession time t, while in the case of PAC the... 

Mossbauer spectroscopy is especially fruitful if the effective field, is one of the parameters determining the shape of the spectrum. is the resultant of the averaging of the hyperfine field but the way in which it is derived depends on the sample. The outcome is determined by comparing the frequency of the fluctuation of the direction with the Larmor precession frequency of the nucleus in the hyperfine field. In a ferromagnetic material, the temperature dependence of is predicted to be the same as the temperature dependence of the expectation value of the atomic spin, and consequently of the magnetization. It thus provides a method for investigating magnetization without the application of external fields. 

The highest energy resolution is obtained by using the neutron spin echo technique. In this type of instrument, the velocities of neutrons incident on, and scattered from, a sample are coded as the number of Larmor precessions that the neutron spins undergo in a well-defined applied magnetic field. The method requires a beam of polarized neutrons with a distribution of velocities. As indicated in Figure 7, these neutrons enter the precession-field region with their spins perpendicular to the field. As a neutron... 

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