First data emerges from ultracold neutrino physics experiment involving Yale

Yale physicists are providing crucial support for an international research collaboration that has released the first results from a novel experiment into why matter outstrips antimatter in the universe.

The Cryogenic Underground Observatory for Rare Events (CUORE) is an experiment designed to confirm the existence of Majorana neutrinos, which scientists believe could hold the key to why there is an abundance of matter over antimatter. The experiment is based at INFN Gran Sasso Laboratories, in Italy.

On April 9, scientists announced early results for the experiment at a number of research institutions in the United States and Italy involved in the project, including Yale and the U.S. Department of Energy’s Lawrence Berkeley National Laboratory. The announcement confirmed the successful demonstration of CUORE’s unique design — a detector made of towers of cubic crystals of tellurium dioxide placed in an ultrapure, high-tech refrigerator that is shielded from cosmic rays and cooled to near absolute zero.

A standalone experiment called CUORE-0 uses the first detector array built for CUORE and operates it in a separate cryostat as a crucial test of the construction procedures for CUORE.

The early results represent data collected over two years and place some of the most sensitive constraints to date on the mass of the elusive Majorana neutrino. In CUORE, researchers are looking for a rare nuclear process called neutrino-less, double-beta decay, a telltale indicator of the Majorana neutrino.

A team from the Yale Wright Laboratory contributed to the operation, commissioning, and data taking of the CUORE-0 detector and helped establish the data analysis procedures that led to the early results.

Yale’s CUORE group includes assistant professor of physics Reina Maruyama; professor of physics Karsten Heeger; associate research scientist Ke Han; postdoctoral associate Kyungeun Lim; graduate students Chris Davis and Jeremy Cushman; and undergraduate students Nikita Dutta, Ivy Wanta, and Tomas Albergo.

Maruyama and Han are members of the CUORE physics board that coordinated the analysis of the CUORE collaboration results. Maruyama is also the Yale representative on the CUORE Council, the board of institutional representatives in the collaboration. She will present the CUORE-0 results in a seminar at Yale Wright Laboratory on April 16.

“After many years of R&D it is satisfying to see the first results from the CUORE detectors,” Maruyama said. “With the full CUORE experiment we will see an order-of-magnitude improvement in sensitivity over current limits. The data show that we are on the right track to build an experiment that has the potential to discover this elusive nuclear decay.”

“CUORE is the perfectly sized experiment, large enough to tackle an essential question of nuclear and particle physics and small enough to get involved in all aspects from detector design to physics analysis,” said Han.

CUORE is supported by the U.S. Department of Energy’s Office of Science, the National Science Foundation, and the Italian National Institute for Nuclear Physics. Support for Maruyama’s group also comes from the Alfred P. Sloan Foundation. The CUORE collaboration is made up of 157 scientists from the United States, Italy, China, France, and Spain.

Yale Wright Laboratory advances the frontiers of fundamental physics through a broad research program in nuclear, particle, and astrophysics, including the study of neutrinos, the search for dark matter, and the study of relativistic heavy ion physics.