Refrigerator

In the search of rare events, such as double beta decay without neutrinos emission, one exploits the fact that in general a small release of energy within a crystal can be interpreted as a change of temperature. This variation can be only measured if the experimental apparatus is kept at extremely low temperatures. At the LNGS the coldest cubic meter of the universe has been created, realizing a cooling system made of concentric shells, that are gradually getting colder and colder.