A Simple Parameterization of the Cosmic-Ray Muon Momentum Spectra at the   Surface as a Function of Zenith Angle
  The designs of many neutrino experiments rely on calculations of the background rates arising from cosmic-ray muons at shallow depths. Understanding the angular dependence of low momentum cosmic-ray muons at the surface is necessary for these calculations. Heuristically, from examination of the data, a simple parameterization is proposed, based on a straighforward scaling variable. This in turn, allows a universal calculation of the differential muon intensity at the surface for all zenith angles and essentially all momenta. 
D. Reyna