The discrepancy

As we have seen in the previous sections, the results of two methods for stopping fraction determination are in disagreement. For the downstream detector En2, we have:

where the disagreement is about 25% (at the 4 $\sigma$ level). Although the absolute amplitude method has about twice as large a quoted error, it is not necessarily less reliable than the relative amplitude method. The advantages of the former include that it: (1) does not rely on the Au component fit in electron spectrum, which can be rather difficult due to the fast time slope, (2) is much less sensitive to the time zero, t₀, position, (3) does not require the corrections via Monte Carlo simulations for the electron detection threshold and decay energy spectrum effects, as well as the relative (upstream versus downstream) solid angle effect, and (4) is not susceptible to the effects of particle emission after muon capture.

On the other hand the disadvantages of the absolute amplitude method include: (1) lack of a complete understanding of the muon loss mechanism in a thin layer, which might affect the results via the branching ratio factor, , (2) possible bias due to the different acceptance functions for electron detection in scintillators (telescope) and $\alpha$detection in Si. It should be stressed, however, that these effects have been estimated rather reliably to be less than a few percent by using our data, and are thus reflected in our quoted errors for this method.