  This paper presents first results of an ongoing study of a possible
association between muon enhancements at ground observed by the TUPI telescope
and transient events such as the Sun's X-ray activity. The analysis of the
observed phenomenon by using the GOES satellite archive data seems to indicate
that on most cases the Ground Level Enhancements (GLEs) could potentially be
associated with solar flares. We show that small scale solar flares, those with
prompt X-ray emission classified as C class (power above $10^{-6}Watts m^{-2}$
at 1 AU) may give rise to GLEs, probably associated with solar protons and ions
arriving to the Earth as a coherent particle pulse. The TUPI telescope's high
performance with these energetic solar particles arises mainly from: (1) its
high counting rate (up to $\sim 100$ KHz). This value in most cases is around
100 times higher than other detectors at ground and (2) due to its tracking
system. The telescope is always looking near the direction of the IMF lines.
The GLE's delay in relation of the X-ray prompt emission suggest that shock
driven by corona mass ejection (CME) is an essential requirement for the
particle acceleration efficiency.
