  It is well known that the cosmic ray intensity observed at the Earth's
surface presents an 11 and 22-yr variations associated with the solar activity
cycle. However, the observation and analysis of this modulation through ground
muon detectors data is make difficult due to the temperature effect.
Furthermore, detector electronic changes or temporary problems may difficult
the analysis of these variations. In this work, we analyze the cosmic ray
intensity observed since October 1970 until December 2012 by the Nagoya muon
detector. We show the results obtained after analyzing all discontinuities and
gaps present in this data and removing changes not related to natural
phenomena. We also show the results found using the mass weighted method for
eliminate the influence of atmospheric temperature changes on muon intensity
observed at ground. Furthermore, we show the preliminary results of the
analysis of the solar cycle modulation on the muon intensity observed for more
than 40 years.
