1000 microsec Figure 3. Disintegration curves for positive and negative muons in aluminum. The ordinates at t=0 can be used to determine the relative numbers of negative and positive muons that have undergone spontaneous decay. The slopes can be used to determine the decay time of each charge species. (From Rossi, p168) Muon physics8 Muon Physics Figure 3. Disintegration curves for positive and negative muons in aluminum. The ordinates at t = 0 can be used to determine the relative numbers of negative and positive muons that have undergone spontaneous decay. The slopes can be used to determine the decay time of each charge species. (From Rossi, p168.)