EMMA is focused on studying the composition of cosmic rays in the energy above 1 PeV-range, the so-called knee region. When a primary cosmic particle collides with the atmosphere, it decays into secondary cosmic particles creating an air shower (muons, electrons, hadrons). The rock above the experiment filters out other particles than high-energy (greater than 45 GeV) muons. EMMA is able to determine the muon shower multiplicity, lateral distribution and direction of entry-measurements. The measurements are performed at the depth of 80 metres in Pyhäsalmi mine. Measurement devices consist of nine detector stations (15 m2 each) and the main part of the detectable area is covered with drift chambers. The drift chambers used in the experiment originate from the DELPHI-experiment at CERN. Additionally the limited streamer tubes and plastic scintillation detectors are part of the measurement stations. External links Centre for Underground Physics in Pyhäsalmi CallioLab References Pyhäjärvi University of Oulu Particle physics facilities Underground laboratories Laboratories in Finland