  We consider a simplified model of the optical multi-pass cavity that is being
currently developed by the FAMU collaboration for the measurement of the
hyperfine splitting in the ground state of muonic hydrogen and of the Zemach
radius of the proton. The model is focused on the time distribution of the
events of laser-stimulated hyperfine transitions in the muonuc atom and may be
helpful in the preliminary design of the FAMU experimental set-up and, more
generally, in the optimization of multi-pass optical cavities for experiments
with pulsed lasers.
