  IceTop is the surface instrumentation of the IceCube Neutrino Observatory at
the South Pole. It is designed to measure extensive air showers of cosmic rays
in the primary energy range from PeV to EeV. Air showers induced by heavier
primary particles develop earlier in the atmosphere and produce more muons
observable at ground level than lighter cosmic rays with the same primary
energy. Therefore, the fraction of muons to all charged particles measured by
IceTop characterizes the mass of primary particles. This analysis seeks a
muon-based mass sensitive parameter by using the charge signal distribution for
each individual cosmic ray event. In this contribution we present the analysis
method for the mass-sensitive parameter and our studies of its possible
application to the measurement of cosmic ray mass composition with the IceTop
surface array.
