On October 7th, 2016, the gravitational wave antenna NAUTILUS (Nuova Antenna a Ultra bassa Temperatura per esplorare In Lontano Universo le Supernovae) has ended its long data collection started in February 2003. In all this time, the 2300 kg aluminum plank was kept at a 2 K temperature in order to overcome problems traditionally linked to continuous helium recovery and refrigeration.
NAUTILUS and its twin AURIGA (at the INFN Laboratory of Legnaro) held the record for sensitivity up until the introduction of gravitational waves interferometers, such as Virgo and LIGO. NAUTILUS was moved from CERN, where the first cryogenic measurements had been taken, to Frascati in the spring of 1992. NAUTILUS, cooled down at 0.1 K, had its first scientific run in 1998, when cosmic rays’ signals were also detected. Indeed, the detector was also used for research on certain hypothetical kinds of dark matter and it was for a long time the coldest solid body in the Universe. Later on, in 2001, to reduce the consume of liquid helium, it was decided to keep the plank at a 2 K temperature. The long run which came to an end in these days was mainly devoted to detecting signals from supernovae within our galaxy. Unfortunately, no cosmic event of this kind was registered after the 1987 supernova.
Last year, the interferometer LIGO detected for the first time the gravitational waves originated from black holes coalescence, starting a new chapter in Physics: gravitational waves Astronomy.