Underground cosmic-ray experiment EMMA

Abstract

EMMA (Experiment with MultiMuon Array) is a new approach to study the composition of cosmic rays at the knee region (1-10 PeV). The array will measure the multiplicity and lateral distribution of the high-energy muon component of an air shower and its arrival direction on an event-by-event basis. The array operates in the Pyhäsalmi Mine, Finland, at a depth of 75 metres (or 210 m.w.e) corresponding to the cut-off energy of approximately 50 GeV for vertical muons. The data recording with a partial array has started and preliminary results of the first test runs are presented.