Department of Energy grant may spur scientists to finally know the incredibly tiny mass of a neutrino

Thomas O’Donnell, an assistant professor in the Department of Physics, has received a $305,000 U.S. Department of Energy grant to seek out the extremely low mass of a neutrino.

O’Donnell, who joined Virginia Tech in 2016, said scientists have only recently discovered that neutrinos coming from nuclear reactors, the Sun, and produced by cosmic rays impacting the atmosphere have a “tiny but non-zero mass.” This mass might be the so-called “Majorana” mass, a technical term for a neutrino that is its own antiparticle, O’Donnell said. 

“One of the consequences if neutrinos have Majorana masses is a process called leptogenesis, which provides a mechanism to seed the matter-antimatter asymmetry we observe in the universe today,” O’Donnell said. “We enjoy the benefits of this still unexplained asymmetry every day as the excess matter makes up the visible universe we experience in our daily lives.”

O’Donnell will carry out these measurements with collaborators at the Cryogenic Underground Observatory for Rare Events (CUORE) laboratory, part of the Gran Sasso National Laboratory in Assergi, Italy. (Thomas previously worked with the group whilst a post-doctorate researcher at the University of California Berkeley.)

O’Donnell added, “Neutrinoless double-beta decay is a low-energy nuclear decay that occurs if neutrinos are Majorana particles. The decay has a particularly robust signature which maybe be seen in high sensitivity experiments.”

At CUORE – the largest operating ultra-low-temperature bolometer array ever built, O’Donnell and collaborators will use an array of almost 1,000 cryogenic particle detectors cooled to within 0.01 Kelvin – that’s minus 449 degree Fahrenheit, darn cold -- of absolute zero temperature. In addition to the weight of mass, the team could discover if the half-life of a neutrino is 10^[26] years – that is 10 multiplies by 10, 26 times.