Studying High $p_T$ Muons in Cosmic-Ray Air Showers

Most cosmic-ray air shower arrays have focused on detecting electromagnetic shower particles and low energy muons. A few groups (most notably MACRO + EASTOP and SPASE + AMANDA) have studied the high energy muon component of showers. However, these experiments had small solid angles, and did not study muons far from the core. The IceTop + IceCube combination, with its 1 km$^2$ muon detection area can study muons far from the shower core. IceCube can measure their energy loss ($dE/dx$), and hence their energy. With the energy, and the known distribution of production heights, the transverse momentum ($p_T$) spectrum of high $p_T$ muons can be determined. The production of these muons is calculable in perturbative QCD, so the measured muon spectra can be used to probe the composition of incident cosmic-rays.