  The main objectives of the KM3NeT Collaboration are i) the discovery and
subsequent observation of high-energy neutrino sources in the Universe and ii)
the determination of the mass hierarchy of neutrinos. These objectives are
strongly motivated by two recent important discoveries, namely: 1) The
high-energy astrophysical neutrino signal reported by IceCube and 2) the
sizable contribution of electron neutrinos to the third neutrino mass
eigenstate as reported by Daya Bay, Reno and others. To meet these objectives,
the KM3NeT Collaboration plans to build a new Research Infrastructure
consisting of a network of deep-sea neutrino telescopes in the Mediterranean
Sea. A phased and distributed implementation is pursued which maximises the
access to regional funds, the availability of human resources and the
synergetic opportunities for the earth and sea sciences community. Three
suitable deep-sea sites are identified, namely off-shore Toulon (France), Capo
Passero (Italy) and Pylos (Greece). The infrastructure will consist of three
so-called building blocks. A building block comprises 115 strings, each string
comprises 18 optical modules and each optical module comprises 31
photo-multiplier tubes. Each building block thus constitutes a 3-dimensional
array of photo sensors that can be used to detect the Cherenkov light produced
by relativistic particles emerging from neutrino interactions. Two building
blocks will be configured to fully explore the IceCube signal with different
methodology, improved resolution and complementary field of view, including the
Galactic plane. One building block will be configured to precisely measure
atmospheric neutrino oscillations.
