In this section, we shall discuss another method for the determination of the stopping fraction, referred to earlier in this chapter as the absolute amplitude method.
In this method, the same fit is performed to the decay electron time spectra as in Fig. 6.5, but we use only the amplitude information for the hydrogen component, and do not rely on the gold component in the fit. With the knowledge of the absolute electron detection efficiency, the number of muon stops in H2 can be directly measured.
The absolute efficiencies for electron detection are determined by taking advantage of a condition called delayed electron coincidence, or Del-e, and delayed telescope coincidence, Del-t (together, generally called Del cuts). These cuts were implemented originally to suppress the muon-capture related background, particularly useful for detection of low energy fusion neutrons from dd fusion [166]. In the Del cut, it is demanded that the electron be observed in the scintillator (telescope) within a certain time window after a hit in a detector of interest (e.g., neutron or Si). This ensure