In practice, differences in counter efficiency and deviations from perfect
geometry complicate the above treatment. If the sensitivity of the
individual positron counters are not the same, the values of the
normalization constant ,
the maximum decay asymmetry and the random background levels
will differ.
The number of recorded
events in each counter also depends on the solid angle they subtend at
the sample. If the coverage of the solid angle is not maximized because
of counter misalignments, there will be a decrease in the number of
decay positrons detected. To account for these differences one can
modify the above results by assuming:

Experimentally one can determine these constants by examining data
above *T*_{c} where the muon precesses around a spatially constant
field. With the above considerations, the raw asymmetry
*A*_{ij}(*t*) for the counters *i* and *j*can then replaced by a *corrected asymmetry*
*A*_{corrected}(*t*).
This is obtained by substituting Eq. (3.29) into
Eq. (3.20) and defining
and
:

2001-09-28