OPERA (Oscillation Project with Emulsion-tRacking Apparatus)
Active, data taking finished. ETH group was in OPERA until the end of 2012.
OPERA (Oscillation Project with Emulsion-tRacking Apparatus) is a long baseline neutrino oscillation experiment to search for the appearance of tau neutrinos in the muon neutrino beam from CERN to the Gran Sasso (CNGS) in Italy. A few muon neutrinos produced at CERN are converted to tau neutrinos on their 730 km flight through the earth’s crust to the Gran Sasso. The signature for a tau neutrino is the observation of the decay of a short-lived charged tau lepton, which was produced in a charge current interaction in the OPERA detector.
The target modules are built from planes containing the basic OPERA detector unit, the lead/emulsion brick. A brick consists of 57 nuclear emulsions interleaved with 56 lead plates of 1 mm thickness. The bricks are about 12 cm wide, 10 cm high, and the thickness in beam direction is about 8 cm, corresponding to 10 radiation lengths. In total, the two target modules contain about 150000 bricks. Behind each brick plane, a plane of horizontal and vertical scintillator strips is mounted (Target Tracker), mainly used to predict the brick, in which a neutrino interaction occurred and to register the precise time of the event. The signature for tau neutrino appearance is the observation of the decay of a short-lived charged tau lepton produced by a charged current interaction. A brick containing a neutrino interaction is removed from the detector with the Brick Manipulation System, the emulsions are developed at LNGS and then sent to the scanning labs in Europe and in Japan.
OOPERA was taking data between 2008 and 2012, collecting about 17500 beam neutrino interactions in the target. About half of the events were scanned and analyzed until the end of 2012.