Stopping Pions in High-Energy Nuclear Cascades

Results of Monte Carlo calculations for the number and energy spectra of charged pions from nuclear-electromagnetic cascades developing in rock are presented for primary hadron energies ranging from 3 to 3000 GeV. These spectra are given as functions of the longitudinal depth in the absorber and the lateral distance from the cascade axis. The number of charged pions which stop in the absorber increases with the primary energy of the hadron initiating the cascade. Knowledge of the $\pi \to \mu \to e$ decays from stopping pions is necessary to interpret certain underground experiments on cosmic-ray muons. Detection of delayed electrons from such decays could be used to estimate primary hadron energies with normal standard deviations ranging from ∼ 66% at 3 GeV to ∼30% at 3000 GeV.