The Cryogenic Underground Observatory for Rare Events experiment (CUORE) reached a new milestone in late January when its detector reached its operating temperature of 10 mk. The detector has 19 towers formed from 988 Tellurium oxide crystals, and it weighs nearly 1,650 lbs. Engineers finished installing the detector into the experiment’s cryostat in August 2016 and have been cooling the system over the last five months.

“We are now seeing clear signals from the detector, and our next phase is the optimization of our electronics and analysis software,” CUORE said in a statement on its website.

Based at Italy’s Gran Sasso National Laboratory, CUORE will study the properties of neutrinos, focusing on a rare phenomenon called neutrinoless double beta decay. Unlike ordinary beta decays, in which electrons and antineutrinos share energy, the neutrinoless double beta decay produces two electrons, but no neutrinos at all. It is as if the two antineutrinos that should have been produced annihilate one another inside the nucleus*.

The experiment is an international collaboration of about 165 scientists from thirty institutions in Italy, the United States, China,and France. CUORE is supported jointly by the Italian National Institute for Nuclear Physics (INFN) and the Department of Energy’s Office of Science and the National Science Foundation in the US.