“Sterile neutrinos” are theoretically predicted new particles that supply an intriguing risk in the quest for understanding the darkish matter in our universe.
Not like the identified “lively” neutrinos in the Standard Model (SM) of particle physics, these sterile neutrinos don’t work together with regular matter as they transfer via area, making them very troublesome to detect.
A crew of interdisciplinary researchers, led by Lawrence Livermore Nationwide Laboratory (LLNL) and the Colorado College of Mines, has demonstrated the energy of utilizing nuclear decay in high-rate quantum sensors in the search for sterile neutrinos. The findings are the first measurements of their variety.
The analysis has been featured not too long ago as a DOE Office of Science Highlight and can jump-start an prolonged venture to look for certainly one of the most promising candidates for darkish matter, the unusual unidentified materials that permeates the universe and accounts for 85 p.c of its whole mass.
The experiment includes implanting radioactive beryllium-7 atoms into superconducting sensors developed at LLNL and has been nicknamed the “BeEST” for “Beryllium Electron-capture with Superconducting Tunnel junctions.” When the beryllium-7 decays by electron seize into lithium-7 and a neutrino, the neutrino escapes from the sensor, however the recoil power of the lithium-7 gives a measure of the neutrino mass. If a heavy sterile neutrino with mass mc2 have been to be generated in a faction of the decays, the lithium-7 recoil power can be decreased and produce a measurable sign, regardless that the elusive neutrino itself shouldn’t be detected instantly.
With a measurement time of simply 28 days utilizing a single sensor, the knowledge excludes the existence of sterile neutrinos in the mass vary of 100 to 850 kiloelectronvolts all the way down to a 0.01 p.c stage of blending with the lively neutrinos — higher than all earlier decay experiments in this vary. As well as, simulations on LLNL supercomputers have helped the crew perceive a few of the supplies results in the detector that should be accounted for to realize confidence in potential sterile neutrino detection occasions.
“This analysis effort lays the groundwork for much more highly effective searches for these new particles utilizing massive arrays of sensors with new superconducting supplies,” mentioned LLNL scientist Stephan Friedrich, lead creator of the analysis showing in Bodily Assessment Letters.
The SM of particle physics is certainly one of the crowning achievements in fashionable science and the cornerstone of present subatomic research. Regardless of its success, the SM is thought to be incomplete, and physics past the Normal Mannequin (BSM) is required to develop a full description of the universe. The neutrino sector gives an intriguing avenue for BSM physics as the commentary of nonzero neutrino plenty at the moment gives the solely confirmed violation of the SM because it was initially constructed.
“Sterile neutrinos are thrilling as a result of they’re sturdy candidates for so-called ‘heat’ darkish matter, they usually additionally might assist to handle the origin of the matter-antimatter asymmetry of the universe,” Friedrich mentioned.
Reference: “Limits on the Existence of sub-MeV Sterile Neutrinos from the Decay of 7Be in Superconducting Quantum Sensors” by S. Friedrich, G. B. Kim, C. Bray, R. Cantor, J. Dilling, S. Fretwell, J. A. Corridor, A. Lennarz, V. Lordi, P. Machule, D. McKeen, X. Mougeot, F. Ponce, C. Ruiz, A. Samanta, W. Ok. Warburton and Ok. G. Leach, 13 January 2021, Bodily Assessment Letters.
Different LLNL authors embody Geonbo Kim, Vincenzo Lordi and Amit Samanta.
This analysis is funded by the Laboratory Directed Analysis and Growth program.