It is often convenient to fit the measured asymmetry in a rotating
reference frame (RRF). To do this, one subtracts a phase
from the phase of Eq. (3.39), where
is the chosen RRF frequency.
The RRF frequency is taken to be slightly lower than
the average Larmor-precession frequency
of
the muon.
The precession signal viewed in this rotating reference frame has only
low frequency components on the order of
,
where
is the average precession frequency in the lab frame. This has two
important consequences. The first is that the quality of the fit
can be visually inspected. Second and most important, it allows
the data to be packed into much fewer bins, greatly enhancing the
speed of fitting.