1.5.2 McFarlane et al. (1985)
The most recent measurement of the p + ->
p 0e+ n branching ratio was reported by McFarlane
et al. in 1985 [McF 85]. The experiment was done at LAMPF and measured
in-flight decays of pions. Figure 1.5 shows a diagram of the apparatus. The
removable CH2 target was only in place for the calibration runs that
alternated with the pion-beta-decay runs. This measurement yielded a value of
(1.026 ± 0.039) ×10-8. The experiment was not an easy one
to perform due to the difficult normalization.
Figure 1.5: The experimental setup from [McF 85]. Charged Pions which decay
in-flight
into neutral pions can be detected by the subsequent neutral pions decaying
into two photons.