The drive along Italy’s highway A24 from the central Adriatic coast towards Rome begins with a winding climb into the snow-covered Apennine Mountains, followed by a plunge into the 10-kilometre-long tunnel under Gran Sasso, the highest peak in the region. About half way through the tunnel, a detour leads off to the right. It reaches a dead end almost immediately at a heavy iron gate. But press the intercom button and utter the words ‘particle physicist’ into the microphone, and the gate slides open like something from a James Bond movie.
Not far beyond the gate is a car park. From there one continues on foot, and begins to get some idea of the scale of the infrastructure hidden beneath the mountain. Opening off a long corridor are three huge halls, each about 20 metres wide, 18 metres high and 100 metres long. This vast area is the home of the Gran Sasso National Laboratory, part of the Italian National Institute of Nuclear Physics (INFN).
In fact, the laboratory’s 180,000 cubic metres of space is not its most valuable attribute. Lying under 1,400 metres of rock, it offers silence — not an absence of sound, but of cosmic-ray noise, the rain of particles constantly bombarding Earth’s surface from space. This lack of cosmic interference has attracted a generation of physicists to these halls, where they can study some of the rarest and most elusive phenomena in the Universe.
Most people probably first heard of Gran Sasso last September, when its OPERA experiment reported — incorrectly, as it turned out — that neutrinos seemed to travel faster than light. But the laboratory, construction of which began 30 years ago, has long been known to physicists. Gran Sasso “was the first true underground laboratory, the only one purposely built for science”, says Stanley Wojcicki, a physicist at Stanford University in Palo Alto, California. It is still by far the largest, serving as a base for 18 experiments and about 950 researchers from 32 countries.
“Gran Sasso’s halls have allowed experiments based on different technologies to work side by side, comparing each other’s pros and cons, and building multiple generations of the same experiments,” says Kevin Lesko, a neutrino physicist at the Lawrence Berkeley National Laboratory in Berkeley, California. The result has been some long-standing underground rivalries. But they have helped to make Gran Sasso one of Italy’s strongest scientific success stories, responsible for a string of notable results in neutrino and solar physics. “It is our trading currency with the international physics community” says INFN president Fernando Ferroni.
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- Nature 485, 435–438 () doi:10.1038/485435a