Spin Precession Simulations

Larmor spin precession is utilized in fundamental physics experiments to measure precise frequencies in particle systems. These frequencies allow for the extraction of many of the most precisely measured parameters in all of physics. As such, precise understanding of all experimental systematic effects is of critical importance. A large class of systematic effects occur when the magnetic field that the particle experiences is not constant, but is instead time dependent. In many cases these time dependent field is both random and complex, resulting in problems challenging for analytic solutions. To solve this problem, we use numerical simulations and Monte Carlo in order to model the effect of these time dependent fields.

Non-Gaussian Phase Distributions

In spin precession measurements of chambered particles, it has often been assumed that after free precession, that the initially polarized particles will form a Gaussian phase distribution in the plane of precession.  Through our simulations, we discovered that this was not the case when time dependent magnetic fields were present.  In the case of an EDM experiment, these time dependent fields arise either from magnetic field gradients or "motional" magnetic fields from a constant electric field.  In the case of a chambered experiment, we found that particles evolved to form Tsallis q-Gaussian distributions which obeyed non-extensive statistics.


  • Bales, M. J., Fierlinger, P. & Golub, R. Non-extensive statistics in spin precession. EPL 116, 43002 (2017) doi: 10.1209/0295-5075/116/43002.



Prof. Dr.sc.nat. Peter Fierlinger