“…This is the starting point for a complicated interplay of competitive collisional and radiative deexcitation processes, the so-called atomic cascade, which ends with the muonic atom being in the 1s ground state. The possibility of a metastable 2p state in muonic hydrogen is currently under investigation [3].Muons, in contrast to the other possible particles, are not affected by strong interaction. So they may serve as the best probe for the investigation of these deexcitation processes.At the investigated hydrogen densities, collisional deexcitation dominates from the beginning of the cascade to low n states, depending on the target density and the kinetic energy of the µp atom [1,5-8].…”