Thursday, the researchers presented the most precise measurement of a neutrino, reducing the maximum possible mass of the spectral mirrors of the matter that permeate our universe.
The result, published in the magazine Science, does not define the exact mass of a neutrino, only its upper limit. But the discovery helps to bring physicists closer to understand what is wrong in the so-called standard model, their best-in-pain-theory of the laws that govern the subatomic kingdom. A way in which physicists know that it is not entirely accurate is that it suggests that the neutrino should not have any mass.
In Grader Scales, learning more about neutrinos will help cosmologists fill their always confused image of the universe, including the way the galaxies have grouped together and what influences the expansion of the cosmos from the Big Bang.
“We are trying to understand why we are here,” said John Wilkerson, physicist at the University of North Carolina, Chapel Hill and author of the new study. “And this is something in which neutrinos can play a key role in”.
Physics know some things about neutrinos. They are prolific throughout the cosmos, created practically at every moment that the atomic nuclei start together or take sides. But they do not bring electric charge and are notoriously difficult to detect.
Neutrines are also available in three types, which physicists describe as flavors. And, strangely, they turn from one flavor to another while moving through space and time, a discovery recognized by the Nobel Prize in Physics in 2015. The mechanism below that makes these transformations possible, physicists have made, means that neutrinos must have a mass.
But only in this way. Neutrinos are slightly light and physicists don’t know why.
Discovering the exact values of the neutrini mass could lead to “a sort of portal” for the new physics, said Alexey Lokhov, a scientist from the Karlsruhe Institute of Technology in Germany. “This is, for now, the best limit in the world,” he said about the measurement of his team.
Dr. Lokhov and his colleagues used the neutrino of Karlsruhe Tritium, or Katrin, to narrow the mass of a neutrino. At one end of the 230 feet long apparatus there was a source of trizio, a heavier version of hydrogen with two neutrons in its nucleus. Since trick is unstable, decays in the Elio: a neutron converts into a proton, which spits an electron in the process. An antineutrin, the antimatter twin of a neutrino, also spits. The two should have an identical mass.
The mass of the original trizio is divided among the products of the decay: helium, electron and antineutrin. Neither neutrinos nor the antineutrins can be detected directly, but one sensor at the other end of the experiment recorded 36 million electrons, over 259 days, paid by the trick in decomposition. Measuring the energy of the electron movement, they could indirectly deduce the maximum possible mass for the antineutrin.
They discovered that the value is no more than 0.45 electronvols, in the mass units used by particles of the particles, a million times lighter than an electron.
The upper limit on the mass was measured for a single neutrino flavor. But Dr. Wilkerson said that nailing the mass of one allows you to calculate the rest.
The last measurement pushes the possible mass of the neutrino less than the previous limit established in 2022 by the collaboration of Katrin, no more than 0.8 electronvolt. It is also almost twice more precise.
Elise Novitski, physics of the University of Washington who was not involved in the work, praised the careful effort of Katrin’s team.
“It’s really just a tour de force,” he said about the experiment and discovery. “I have full confidence in their result.”
Katrin’s team is working on an even closer limit on the mass of 1,000 days of data neutrinos, which plans to collect by the end of the year. This will give to physicists even more electron to measure, leading to a more precise measurement.
Other experiments on the horizon will also contribute to a better understanding of the neutrino mass, including project 8 in Seattle and the experiment of underground neutrinos, released in two physics structures in the Midwest.
The astronomers who study the structure of the cosmos in general, considered influenced by the vast collection of neutrinos that flood the universe, have their measurement of the maximum mass of the particles. But according to Dr. Wilkerson, the boundaries established by astronomers who fixed the void do not correspond to what the particles of the particles calculate in the laboratory, while examining the subatomic world.
“There is something really interesting in progress,” he said. “And the probable solution will be physical beyond the standard model.”