The Dark Side of the universe

It was recently launched in the heart of the Gran Sasso National Laboratory, managed by the National Institute of Nuclear Physics, the experiment Dark Side -50. Its goal: to go in search of the elusive WIMP, this should be the main constituents of dark matter in the universe.

The core of the detector dark matter Dark Side during a stage of assembly.



It opens a new chapter in a heated race to the identification of dark matter , the elusive ‘ ingredient ‘ which, according to current theories , constitute 20-25 percent of the total mass of the universe and that has not yet been identified nor characterized .

Scientists can only speculate for now and hope that the more recent experiments can finally give some indications on the nature of dark matter. A few months ago we broke the news of the first results of LUX (Large Underground Xenon experiment that is the apparatus installed in the heart of a gold mine in South Dakota, United States). Beside it, in this exciting hunt, is also Dark Side-50, a developer recently put into operation in one of the underground chambers of the National Laboratories of Gran Sasso National Institute of Nuclear Physics (INFN) in Abruzzo. As well as LUX, Dark Side-50 is designed to identify the elusive WIMPS, weakly interacting massive particles with ordinary matter which are among the biggest suspects as constituents of dark matter. And as its ‘colleague’ overseas, Dark Side has been installed in the bowels of a mountain in order to minimize spurious effects due to cosmic rays. The research program sees extensive international collaboration, with 17 American institutions, INFN and other centers in Italy, France, Poland, Ukraine, Russia and China. Peter Meyers, a professor of physics at Princeton University and one of the scientists leading the project said: “We have a good idea of what to look for, but we do not know exactly where or when we will find it.”

“The INFN has contributed significantly to the installation of the experiment in what is one of its laboratories of excellence,” adds Gioacchino Ranucci, Head Technologist INFN Milano, involved in project management. ” Dark Side-50 is another piece of energetic, multi-year cooperation Italy – USA at Gran Sasso , which culminated in particular in the development of techniques for particle detection in radio-purity levels never reached before, and extensively re-used and enhanced in the construction of the apparatus” .

A system is designed consisting of a two-stage detector the size of a shopping bag, containing 38 liters of pure argon which have been liquefied by cooling them to a temperature of minus 186 Celsius. The active part of the detector, wrapped in a structure of Teflon, contains 150 kilograms of argon (50 of which are active, hence the name Dark Side-50). At the top and bottom of the container that accommodates the detector, photodetectors have been installed that are able to pick up the light produced by the impact of WIMP with atoms of ultrapure argon. The whole device is housed inside of a steel ball the size of a room and filled with 30,000 liters of liquid scintillator. In turn, the ball is suspended by the supports within a large cylindrical tank 10 meters high (more or less a three-storey house ) and with a diameter of 11 filled with a million liters of purified water.


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