Thursday, September 23

Unusual neutrinos can open the door to the dark side

The hypothetical sterile neutrinos can be detected with quantum sensors and confirm that they are the particles that make up dark matter, has discovered a research whose results are published in the journal Physical Review Letters.

The neutrinos they are very particular subatomic particles: they have mass, but very small and difficult to measure. They are surprising because the mass they contain is not contemplated in the Standard Model that describes the subatomic world.

There are three types or flavors of neutrinos: electronic, muonic, and tauonic, all experimentally proven. Scientists suspect that there must be a fourth type, which they have called a sterile neutrino, because it would never interact with anything other than another neutrino.

The sterile neutrino has not been experimentally verified, but scientists have detected clear indications of its presence and believe that the Standard Model must be expanded to accommodate its existence.

The Standard Model of particle physics is one of the most important developments in science, but many scientists believe that its current limits must be transcended to develop a more complete description of the universe.

Sterile Neutrino

Sterile Neutrino Although the sterile neutrino is still a hypothetical particle, its eventual existence has the potential to revolutionize Physics: it would surely illuminate another Standard Model more complex than the current one.

Since they do not interact with normal matter when they move through space, sterile neutrinos are difficult to detect, although last month a Fermilab experiment obtained new evidence that they might actually exist.

Based on this result, which confirms an earlier experiment from the 1990s, some of the measured muon neutrinos turn into sterile neutrinos before changing identity back to electron neutrinos.

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Quantum sensors

Quantum sensors New research, led by the Lawrence Livermore National Laboratory (LLNL) and the Colorado School of Mines (USA), proposes a new way of proving its existence, as reported in a release.

This study, led by Stephan Friedrich, finds that nuclear decay in high-speed quantum sensors can be used to detect sterile neutrinos.

The new experiment uses radioactive beryllium-7 atoms created at the facilities of Canada’s national particle acceleration center (TRIUMF). The research team implants these atoms in sensitive superconductors cooled to almost absolute zero.

This experiment does not look for dark matter particles directly. Instead, it measures the signature of atoms produced in certain radioactive decays, which would be affected by sterile neutrino dark matter particles.

This is a powerful experimental method, since it presupposes the existence of this new type of particle, and not just how that particle could hypothetically interact with normal matter. In this sense, it represents an important innovation with respect to the methods developed so far to search for sterile neutrinos.

Skimming the dark matter

Skimming the dark matter If this system works, as everything seems to indicate, we could not only verify the existence of sterile neutrinos, but also verify that they have enough mass to form the dark matter that surrounds galaxies. They can also explain why the Universe contains more matter than antimatter.

That is, we would have found the core of dark matter, a type of matter that is not dark energy, or ordinary matter, or any of the three known types of neutrinos, but that occupies about 80 percent of the matter in the universe. .

Dark matter is so called not only because it does not emit, absorb or reflect light, nor any other form of radiation, but also because it does not have an electromagnetic charge and does not interact with any other form of matter, except through gravity.

Its mystery increases when verifying that dark matter is not made up of the usual particles, such as electrons, protons or electrons, so it has been thought that it must be formed by a particle not recognized by the Standard Model: sterile neutrinos are the candidates favorites and now it seems that we are about to confirm their existence and discover the greatest secret of dark matter.


Reference Limits on the Existence of sub-MeV Sterile Neutrinos from the Decay of 7Be in Superconducting Quantum Sensors. S. Friedrich et al. Phys. Rev. Lett. 126, 021803, 13 January 2021. DOI:

Top photo: Composite image of the CL0024 + 17 galaxy cluster taken by the Hubble Space Telescope showing the creation of a gravitational lensing effect. This effect is assumed to be due, in large part, to gravitational interaction with dark matter. NASA, ESA, MJ Jee and H. Ford (Johns Hopkins University).

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