KM3NeT is a multi-cubic-kilometer neutrino telescopes under construction in the Mediterranean Sea. KM3NeT will study of neutrinos of cosmic origin in the TeV-PeV energy range, and neutrino oscillation and mass hierarchy using atmospheric neutrinos in the GeV range. Both projects will use the same design of active elements to detect Cherenkov light of charged secondary particles – the optical modules. In the current first phase of the project, 31 detection units – a few hundred meters high vertical structures holding 18 Digital Optical Modules (DOMs) each – will be produced and deployed in the Mediterranean deep sea. The KM3NeT DOM consists of pressure resistant glass sphere encapsulating 31 photomultiplier tubes of 80 mm diameter produced by Hamamatsu, readout electronics and additional instrumentation for calibration and monitoring. The use of ~3 inch diameter PMTs recently developed by ETL, HZC and MELZ is under investigation. This contribution describes the design and characteristics of the KM3NeT DOM and reviews suitable PMT types for this application.

Erlangen Centre for Astroparticle Physics, University of Erlangen-Nuremberg