Of all the matter in the visible universe, only 4% is normal matter, as the matter from which all the things we know are formed. 23% is made of dark (invisible) matter, which physicists intuit exists, but do not know what it is. The remaining 73%, that is, almost all the matter in the universe, is dark energy, which is also invisible.
Now, a detector, the most isolated from external influences from around the world, aspires to locate part of this elusive universe: specifically, the existence of dark matter.
Under a mountain of Itali is the XENON1T. With a total mass of about 3,200 kilos, XENON1T is eThe largest detector of this type ever built. This last detector of the XENON family has been in scientific operation in the Gran Sasso underground laboratory (Italy) since autumn 2016.
Its shape is that of a gigantic cylindrical metal tank filled with ultra pure water to protect the detector in its center and a three-story building, transparent, where the detectors are located.
The XENON1T central detector, a liquid xenon time projection camera (LXeTPC), is located in the bowels of a cryostat in the middle of the water tank, fully submerged in order to protect it as much as possible from the natural radioactivity in the cave.
But this is not enough level of isolation, because all materials on Earth contain small traces of natural radioactivity.
An interaction of particles in liquid xenon leads to small flashes of light. This is what XENON scientists are recording and studying to infer the position and energy of the interacting particle, and whether or not it may be dark matter. As he explains Elena Aprile, professor at Columbia University and spokesperson for the project:
The best news is that the experiment continues to accumulate excellent data, which will allow us to test the WIMP hypothesis (hypothetical particles that could explain the problem of dark matter) very soon in a region of mass and cross section with normal atoms like never before .