An international team of scientists releases early results from the CUORE experiment with implications for why there’s more matter than antimatter in the universe.
Today an international team of nuclear physicists announced the first scientific results from the Cryogenic Underground Observatory for Rare Events (CUORE) experiment. CUORE, located at the INFN Gran Sasso National Laboratories in Italy, is designed to confirm the existence of the Majorana neutrino, which scientists believe could hold the key to why there is an abundance of matter over antimatter. Or put another way: why we exist in this universe.
The results of the experiment, called CUORE-0, were announced at INFN Gran Sasso Laboratories (LNGS) in Italy, the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), and at other institutions in the US.
The findings are twofold. First, the CUORE-0 results place some of the most sensitive constraints on the mass of the elusive Majorana neutrino to date. With these new constraints, the CUORE team is essentially shrinking the size of the haystack that hides the Majorana needle, making it much more likely to be found.
Second, the experiment, successfully demonstrates the performance of CUORE’s novel design—a detector made of towers of Rubik’s cube-sized crystals of tellurium dioxide. These towers are placed in a high-tech refrigerator that has been painstakingly decontaminated, shielded from cosmic rays, and cooled to near absolute zero.
Today’s results represent data collected over two years from just one tower of tellurium dioxide crystals. By the end of the year, all 19 towers, each containing 52 crystals, will be online, increasing CUORE’s sensitivity by a factor of 20.
“CUORE-0 is so far the largest detector operating at a temperature very close to absolute zero,” says Dr. Oliviero Cremonesi of INFN-Milano Bicocca, spokesperson for the CUORE collaboration. “CUORE is presently in its final stages of construction, and when completed, it will study the nuclear processes associated with the Majorana neutrino with unprecedented sensitivity.”
“With the CUORE-0 results, we’ve proven that our experimental design, materials, and processes, which include extremely clean surfaces, pure materials, and precision assembly, are paying off,” says Yury Kolomensky, senior faculty scientist in the Physics Division at Berkeley Lab, professor of physics at UC Berkeley, and U.S. spokesperson for the CUORE collaboration.
Annihilations in the Early Universe
To pin down the Majorana neutrino, the researchers are looking for a telltale indicator, a rare nuclear process called neutrinoless double-beta decay. This process is expected to occur infrequently, if at all: less than once every septillion (a trillion trillion, or, a 1 followed by 24 zeros) years per nucleus.
Unlike regular double-beta decay, which emits two anti-neutrinos, neutrinoless double-beta decay emits no neutrinos at all. It’s as if one of the anti-neutrinos has transformed into a neutrino and cancelled—or annihilated—its sibling inside the nucleus.
“In 1937, Ettore Majorana predicted that neutrinos and anti-neutrinos could be two manifestations of the same particle - in modern language, they are called Majorana particles,” says Reina Maruyama, assistant professor of physics at Yale University, and a member of the CUORE Physics Board, which guided the analysis of the data. “Detecting neutrinoless double-beta decay would lead us directly to the Majorana particle, and give us hints as to why the universe has so much more matter than antimatter.”
Known laws of physics forbid such matter-antimatter transformations for normal electrically charged particles like electrons and protons. But neutrinos, which are electrically neutral, may be a special kind of matter with special capabilities.
The proposed matter-antimatter transitions, while extraordinarily rare now, if they happen at all, may have been common in the universe just after the big bang. The remainder of existence, then, after all the annihilations, would be the matter-full universe we see today.
The CUORE crystals of tellurium dioxide are packed with more than 50 septillion nuclei of tellurium-130, a naturally occurring isotope that can produce double-beta decay and possibly neutrinoless double-beta decay. For the experiment, the crystal towers sit in an extremely cold refrigerator called a cryostat that’s cooled to about 10 milliKelvin or -273.14 degrees Celsius. Last year, the CUORE cryostat set a record for being the coldest volume of its size.
In the very cold CUORE crystals, presence of both nuclear processes would produce small but precisely measured temperature rises, observable by highly sensitive temperature detectors within the cryostat. These temperature increases correspond to spectra—essentially the amount of energy given off—from the nuclear event. Two-neutrino double-beta decay produces a broad spectrum. In contrast, neutrinoless double-beta decay would create a characteristic peak at the energy of 2528 kiloelectron-volts. This peak is what the researchers are looking for.
The CUORE experiment sits about a kilometer beneath the tallest mountain of the Apennine range in Italy, where rock shields it from cosmic rays. This location, as well as the experimental design, enables the sensitivity required to detect neutrinoless double-beta decay.
"The sensitivity demonstrated by the results today is outstanding,” says Stefano Ragazzi, director of the INFN Gran Sasso National Laboratories. “The INFN Gran Sasso Laboratories offers a worldwide unique environment to search for ultra-rare interactions of Majorana neutrinos and dark matter particles and is proud to host the most sensitive experiments in these fields of research."
“While there’s no direct evidence of the Majorana neutrino yet, our team is optimistic that CUORE is well positioned to find it,” says Ettore Fiorini, professor emeritus of physics at the University of Milano-Bicocca and founding spokesperson emeritus of the experiment. “There is a competition of sorts, with other experiments using complementary techniques to CUORE turning on at about the same time. The next few years will be tremendously exciting.”
CUORE is supported jointly by the Italian National Institute for Nuclear Physics Istituto Nazionale di Fisica Nucleare (INFN) in Italy, and the Department of Energy’s Office of Science and the National Science Foundation in the US. The CUORE collaboration is made of 157 scientists from Italy, U.S., China, France, and Spain, and is based in the underground Italian facility called INFN Gran Sasso National Laboratories(LNGS) of the INFN.
The National Institute for Nuclear Physics (INFN) is the Italian research agency dedicated to the study of the fundamental constituents of matter and the laws that govern them, under the supervision of the Ministry of Education, Universities and Research (MIUR). It conducts theoretical and experimental research in the fields of subnuclear, nuclear and astroparticle physics. Website: www.infn.it
Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.
Kate Greene | newswise
JILA researchers make coldest quantum gas of molecules
22.02.2019 | National Institute of Standards and Technology (NIST)
(Re)solving the jet/cocoon riddle of a gravitational wave event
22.02.2019 | Max-Planck-Institut für Radioastronomie
An international research team including astronomers from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has combined radio telescopes from five continents to prove the existence of a narrow stream of material, a so-called jet, emerging from the only gravitational wave event involving two neutron stars observed so far. With its high sensitivity and excellent performance, the 100-m radio telescope in Effelsberg played an important role in the observations.
In August 2017, two neutron stars were observed colliding, producing gravitational waves that were detected by the American LIGO and European Virgo detectors....
Up to now, OLEDs have been used exclusively as a novel lighting technology for use in luminaires and lamps. However, flexible organic technology can offer much more: as an active lighting surface, it can be combined with a wide variety of materials, not just to modify but to revolutionize the functionality and design of countless existing products. To exemplify this, the Fraunhofer FEP together with the company EMDE development of light GmbH will be presenting hybrid flexible OLEDs integrated into textile designs within the EU-funded project PI-SCALE for the first time at LOPEC (March 19-21, 2019 in Munich, Germany) as examples of some of the many possible applications.
The Fraunhofer FEP, a provider of research and development services in the field of organic electronics, has long been involved in the development of...
For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.
The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...
Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens
Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...
Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light
When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...
11.02.2019 | Event News
30.01.2019 | Event News
16.01.2019 | Event News
22.02.2019 | Physics and Astronomy
22.02.2019 | Materials Sciences
22.02.2019 | Life Sciences