Performances and main results of the KM3NeT prototypes

International audienceThe KM3NeT collaboration aims to build a km3-scale neutrino telescope in the Mediterranean Sea. The first phase of construction comprises the deep-sea and onshore infrastructures at the KM3NeT-It (100 km offshore Capo Passero, Italy) and KM3NeT-Fr (40 km offshore Toulon, France) sites and the installation of 31+7 detection units. For the next step (KM3NeT 2.0) completion of two detectors are planned as extension of the detectors realized during the first phase of construction: ARCA for high energies (E > TeV) in Italy and ORCA for low energies (GeV range) in France. A prototype digital optical module made of 31” PMTs was deployed in April 2013 inside the ANTARES neutrino telescope. This prototype, attached to an ANTARES string, was operated for one year and a half. It validated the multi-PMT technology and demonstrated the capability to identify muons with a single optical module searching for local time coincidences between PMTs inside the optical module. A prototype detection unit made of three optical modules was installed at the KM3NeT-It site. It was deployed in May 2014; it is active and taking data. More than 700 hours of data have been recorded and analyzed. The experience achieved with this prototype detection unit validates the submarine deployment procedures, the mechanics and the electronic of the apparatus, the data taking and analysis procedures. Through the study of 40K decay in sea water and dedicated data taking periods with flashing LED nanobeacons, it is possible to calibrate in time the detector with nanosecond stability. A dedicated algorithm has been developed to select atmospheric muons and reconstruct their zenith angle with a resolution of about 8 degrees. An excellent agreement is found when comparing the detected signal from muons with Monte Carlo simulations