The Digital Optical Module of KM3NeT

The KM3NeT Collaboration is currently building neutrino telescopes with a total volume of about a cubic kilometre at the bottom of the Mediterranean Sea. The detectors consist of matrices of photodetectors, called digital optical modules, suspended in the depths of the sea by means of vertical structures, called detection units. For the optical modules, KM3NeT uses a new design that hosts 31 3-inch photomultiplier tubes and all the associated electronics inside a pressure-resistant glass vessel with a 17-inch diameter. This solution represents an innovative design with several advantages with respect to optical modules that comprise single large photomultipliers, currently used in all other operational neutrino telescopes. The digital optical module mass production phase has already started in several integration sites, together with the installation of detection units in the depths of the Mediterranean Sea. (paper)