The ghost is finally inside the machine: scientists have successfully produced neutrinos in a particle collider for the first time. These plentiful yet mysterious subatomic particles have the term “ghost particles” because they are so different from other kinds of matter that they pass through it like specters. According to the scientists, this effort constitutes the first direct observation of collider neutrinos and will aid in our understanding of the formation, characteristics, and significance of these particles in the development of the universe.
The findings were reported at the 57th Rencontres de Moriond in Italy, utilizing the FASERnu detector at the Large Hadron Collider. “We’ve detected neutrinos from a new source – particle colliders – where 2 beams of particles crash together at extraordinarily high intensity,” explains particle physicist Jonathan Feng of the University of California, Irvine.
Only photons are more prevalent among subatomic particles in the universe than neutrinos. Yet, they lack any electric charge, have almost no mass, and scarcely interact with other particles. Many thousands of trillions of neutrinos are currently passing through your body. Nuclear fusion within stars and supernova explosions are two examples of intense processes that produce neutrinos. And although while we might not see them on a daily basis, physicists think that their mass, however small, likely influences the gravitational pull of the Universe (although neutrinos have pretty much been ruled out as dark matter).
Even though their connection with matter is minimal, they occasionally collide with another particle to produce a very tiny flash of light, proving that their interaction with matter is not entirely nonexistent. These bursts are detectable using underground detectors that are shielded from other radiation sources. Three of these detectors are MiniBooNE at Fermilab in Illinois, Super-Kamiokande in Japan, and IceCube in Antarctica.
However since the high energies involved are less well understood than low-energy neutrinos, scientists have long sought neutrinos created in particle colliders. Particle scientist Jamie Boyd of CERN claims, “They can tell us all about outerspace in manners we can’t learn about it otherwise. “These extremely high-energy neutrinos produced by the LHC are critical for understanding some of the most exciting particle astrophysics findings,”
Using millimeter-thick tungsten plates and layers of emulsion film alternately, FASERnu is an emulsion detector. The detector is made up of 730 emulsion films and a total mass of about 1 ton of tungsten, which was chosen for the detector due to its high density, which improves the possibility of neutrino interaction. At the LHC, neutrinos can hit with tungsten plate nuclei to produce particles that leave traces in the emulsion layers, much like ionizing radiation does in a cloud chamber.
Before physicists can examine the particle trails to determine what caused them, these plates must be processed, much like photographic film. In 2021, six potential neutrino candidates were found and reported. With a significance level of 16 sigma, the researchers have now verified their discovery using data from the third run of the improved LHC, which started last year.
A level of significance of 5 sigma is needed to be recognized as a discovery in particle physics, which signifies that the probability that the signals were generated by chance is so small as to be almost nothing. The FASER team is currently working diligently to analyze the data gathered by the detector, and it appears likely that numerous additional neutrino detections will follow. Data gathering and analysis are still going on for Run 3 of the LHC, which is anticipated to last until 2026.
We have only begun to explore what FASERnu has to offer; in 2021, physicist David Casper of the University of California, Irvine, predicted that the run would generate about 10,000 neutrino interactions. He claims that because neutrinos are the only known particles that the Large Hadron Collider’s more robust experiments are unable to directly detect, FASER’s successful observation signals that the collider’s full physics potential is now being realized.