Forty different universities and institutions from across Europe
are partnering on a project to build a neutrino observatory under
the Mediterranean sea that will be the second-largest structure
ever built by humans, after the Great Wall of China.
The KM3NeT telescope will
have a volume of "several" cubic kilometres -- hence the odd name,
which purportedly stands for "kilometre-cubed neutrino telescope".
It will comprise of a number of towers -- each taller than the
830-metre Burj Khalifa in Dubai -- which will be filled with
spheres containing photomultiplier tubes, which will record
neutrinos passing through.
Neutrinos are notoriously tricksy little particles, formed in certain types
of radioactive decay. They get their name because they carry no
electrical charge, but that property also means that they can pass
through matter virtually unimpeded, making them difficult to spot.
Whereas an electron passing through a 3-centimetre thick sheet of
metal will lose significant amounts of energy, a neutrino of the
same energy would need something like a light-year's worth of heavy
metal to lose the same amount.
Peter Fisher, a particle physicist at MIT, explained
to Popsci: "Anytime you detect a particle, what
you're always doing is having the particle interact with some kind
of matter, whether it's water, steel, air or ice. The less the
particle interacts, the more material you need for it to interact
KM3NeT uses the ocean instead. Hundreds of metres of seawater
act as a shield, blocking interference from particles generated in
our atmosphere, and allow the photomultipliers to capture the
bright blue flash caused when a neutrino hits the nucleus of an
atom and produces a charged particle known as a muon.
Riccobene, a staff researcher at the Italian National Institute
for Nuclear Physics, said: "This is the light we look for to
reconstruct the trajectory of the muon," Riccobene said. "So, in
this sense, it is an underwater telescope. The water allows us to
see the reaction more clearly."
The structure is still in the planning phases, and funding
is proving problematic given the current state of
European finances and politics, but if all goes well then
construction could begin as early as 2012.