Speaker
Dr
Emanuele Leonora
(INFN-sezione di Catania)
Description
The KM3NeT European project aims to construct a large volume underwater neutrino telescope in the depths of the Mediterranean Sea. Thanks to a dedicated funding by the Italian Ministry of Education, University and Research (MIUR) in its first phase, referred as KM3NeT-Italia, an 8-towers detector is under construction.
The detection element of the telescope, the optical module, is composed by a 13-inch high-pressure glass-vessel that contains a single 10-inch photomultiplier, optically and mechanically coupled by means of a transparent silicone gel. A mu-metal cage surrounds the photomultiplier to shield it against the Earth's magnetic field. The power supply system, the front-end electronic module and a LED-system designed for underwater calibrations are also hosted into the glass sphere, together with a manometer to check the vacuum inside the vessel.
The whole optical module design, as well as each single component, was chosen after an intense R&D work on photomultipliers, high voltage supply circuit, optical gel and mechanical supports.
Before the production phase, 750 of the selected 10-inch R7081 Hamamatsu photomultipliers have been thoroughly characterized by means of dedicated test-benches.
Following a well-established production procedure, over 700 optical modules were assembled at the INFN-LNS production site located at the Harbour of Catania, and their functionality tested from electrical and mechanical point of view by using properly test-benches and a hyperbaric chamber.
The proposed talk deals with the definitive design of the whole optical module, describing its main components, the main results obtained from the massive photomultipliers measurements, and the foremost phases of the mass production procedure.
In November 2014 a first tower of 14 storeys equipped with 84 optical modules was deployed in the Mediterranean Sea site, at a depth of over 3500 meter.
Primary author
Dr
Emanuele Leonora
(INFN-sezione di Catania)
Co-authors
Dr
Sebastiano Aiello
(INFN-sezione di Catania)
Dr
Valentina Giordano
(INFN-sezione di Catania)
