Simultaneous observation of extensive air showers and deep-underground muons at the Gran Sasso Laboratory.

Abstract

Combined measurements of extensive air showers at the surface and high-energy muons deep underground have been initiated at the Gran Sasso Laboratory. The underground detector is the first supermodule of MACRO (area = 140 ${\mathrm{m}}^{2}$, depth = 3100 m of water equivalent, ${E}_{\ensuremath{\mu}}g1.3$ TeV) and the surface detector is the EAS-TOP array (altitude 2000 m above sea level, total enclosed area $A\ensuremath{\sim}{10}^{5}$ ${\mathrm{m}}^{2}$). We discuss the correlation technique, the comparison between the shower parameters as determined by the two detectors, and some of the characteristics of the reconstructed events.