28th International Cosmic Ray Conference 997 Underground Multimuon Experiment in Pyhäsalmi Mine

The CUPP project is preparing an experiment in the Pyhäsalmi mine in order to observe simultaneous, multiple muon events originated from extensive air showers. The detection of the multimuon events is motivated by partly unknown composition and origin of the primary cosmic rays in the energy region of 1015 – 1016 eV, i.e. the ’knee ’ region. The experiment will be situated in shallow depths in the Pyhäsalmi mine, and it can be carried out with two or three detector units of an area of about 100 m2 each and with mutual separation of about 30 m. The existing free caverns will be used. Detectors can be placed at different depths between 95 and 400 m (250 – 1000 mwe) for measuring different properties of the air shower. 1