Measurement of the ratio double/single muon events as a function of rock   depth with MACRO
  We report the measurement by the MACRO experiment of the ratio of double muon events over single muon events as a function of rock depth. Particular attention has been devoted to the analysis of high zenith angle events. Results are compared to the expectation of a detailed simulation performed with HEMAS-DPM Monte Carlo. No deviations with respect to ``standard physics'' predictions have been found. 
M. Sioli (Bologna University and INFN) (for the MACRO Collaboration)