Thu. Jan 20th, 2022


In 1993, deep Underground at the Los Alamos National Laboratory in New Mexico, a few flashing lights inside a bus-sized tank of oil begins a detective story that has yet to reach its conclusion.

The Liquid Sentilator Neutrino Detector (LSND) was looking for radiation explosions caused by neutrinos, the lightest and most elusive of all known elementary particles. “To our surprise, that’s what we saw,” said Bill Louis, one of the test leaders.

The problem was that They have seen a lot. Theorists have speculated that neutrinos explain different types of astronomical observations – a hypothesis that explains different types of astronomical observations. The LSND set out to test this idea by using a beam of muon neutrinos, one of three known types, aimed at the oil tank and counting the number of electron neutrinos arriving there. Yet Louis and his team have discovered that much more electrons are coming into the neutrino tank than was predicted by the general theory of neutrino oscillations.

Since then, dozens more neutrino experiments have been made, each larger than the last. Mountains, unused mining caves and ice beneath the South Pole, physicists have built cathedrals for these infamous slippery particles. But since these experiments examine neutrinos from every angle, they paint conflicting pictures of how particles behave. “The plot tends to get thicker,” Louis said.

“It simply came to our notice then. I call it the Garden of Forking Path, ”he said Carlos Arguelles-Delgado, A neutrino physicist at Harvard University. In Jorge Luis Borges’ short story of that title in 1941, time branches out into an infinite number of possible futures. With neutrinos, conflicting results have sent theorists in different directions, not sure which information to believe and which could lead them astray. “Like any detective story, sometimes you see clues and they mislead you,” said Arguelles-Delgado.

In 1993, the Los Alamos National Laboratory’s Liquid Sentilator Neutrino Detector reported a surprising generosity of neutrino detection. Rick Bolton, an engineer, has been shown kneeling between photomultiplier tubes that will detect light from neutrino interactions inside the tank once it is filled with mineral oil.Courtesy of Los Alamos National Laboratory

The simplest explanation for the LSND incompatibility was the existence of a new, fourth type of neutrino, called sterile neutrino, which mixes all neutrino types according to the new rules. Sterile neutrinos allow muon neutrinos to sway more easily to electron neutrinos at short distances from the oil tank.

But over time, sterile neutrinos do not match the results of other tests. “We had our champion theory, but the problem was elsewhere it failed miserably,” said Arguelles-Delgado. “We were very deep in the woods, and we had to get out.”

Forced to get their steps back, physicists are reconsidering what lies behind the hint and half-result noise. In recent years, they have developed new theories that are more complex than sterile neutrinos, but which, if accurate, will revolutionize physics thoroughly সমাধান resolving the inconsistencies of neutrino oscillation data and other major mysteries of physics at the same time. Not least, the new models carry heavy extra neutrinos that could be responsible for the dark matter, the invisible material covering the galaxies that seem to be four times more abundant than normal matter.

Now, Four analyzes published yesterday by the MicroBooNE test At the Fermi National Accelerator Laboratory near Chicago and Another recent study of icecube detectors At the South Pole, both suggest that these more complex neutrino theories may be on the right track – although the future is not yet clear.

“I think there’s something in the air,” said Arguelles-Delgado. “It’s a very exciting environment that points to discovery.”

A desperate remedy

When Wolfgang Pauli speculated about the existence of neutrinos in 1930 to explain where energy is lost during radioactive decay, he called it a “desperate remedy.” There was no mass or electrical charge in his theoretical construction, making him doubt that an experiment could ever detect it. “It’s something a theorist should never do,” he wrote in his journal at the time. But in 1956, in an experiment not unlike LSND, There were neutrinos.

Triumph soon fell into disarray when physicists identified neutrinos from the Sun, a natural source of particles, and found less than half the number predicted by theoretical models of star nuclear reactions. In the 1990’s, it was clear that neutrinos were behaving strangely. Not only do solar neutrinos seem to have mysteriously disappeared, but neutrinos also fell to Earth when cosmic rays collided with the upper atmosphere.



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