Kuusiniemi, Pasi; Bezrukov, L.; Enqvist, Timo; Fynbo, H.; Inzhechik, L; Joutsenvaara, J.; Kalliokoski, Tuomo; Loo, Kai; Lubsandorzhiev, B.; Monto, Tiia; Petkov, V.; Räihä, T.; Sarkamo, J.; Slupecki, M.; Trzaska, Wladyslaw; Virkajärvi, A. 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

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... s 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.