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posted by janrinok on Monday November 29 2021, @04:32AM   Printer-friendly
from the found-at-last dept.

upstart, with similar submissions from Frigatebird and others, writes:

Physicists detect signs of neutrinos at Large Hadron Collider:

The international Forward Search Experiment team, led by physicists at the University of California, Irvine, has achieved the first-ever detection of neutrino candidates produced by the Large Hadron Collider at the CERN facility near Geneva, Switzerland.

In a paper published today in the journal Physical Review D, the researchers describe how they observed six neutrino interactions during a pilot run of a compact emulsion detector installed at the LHC in 2018.

"Prior to this project, no sign of neutrinos has ever been seen at a particle collider," said co-author Jonathan Feng, UCI Distinguished Professor of physics & astronomy and co-leader of the FASER Collaboration. "This significant breakthrough is a step toward developing a deeper understanding of these elusive particles and the role they play in the universe."

He said the discovery made during the pilot gave his team two crucial pieces of information.

"First, it verified that the position forward of the ATLAS interaction point at the LHC is the right location for detecting collider neutrinos," Feng said. "Second, our efforts demonstrated the effectiveness of using an emulsion detector to observe these kinds of neutrino interactions."

The pilot instrument was made up of lead and tungsten plates alternated with layers of emulsion. During particle collisions at the LHC, some of the neutrinos produced smash into nuclei in the dense metals, creating particles that travel through the emulsion layers and create marks that are visible following processing. These etchings provide clues about the energies of the particles, their flavors—tau, muon or electron—and whether they're neutrinos or antineutrinos.

According to Feng, the emulsion operates in a fashion similar to photography in the pre-digital camera era. When 35-millimeter film is exposed to light, photons leave tracks that are revealed as patterns when the film is developed. The FASER researchers were likewise able to see neutrino interactions after removing and developing the detector's emulsion layers.

[...] With the success of their neutrino work over the past few years, the FASER team—consisting of 76 physicists from 21 institutions in nine countries—is combining a new emulsion detector with the FASER apparatus. While the pilot detector weighed about 64 pounds, the FASERnu instrument will be more than 2,400 pounds, and it will be much more reactive and able to differentiate among neutrino varieties.

Journal Reference:
Henso Abreu, Yoav Afik, Claire Antel, et al.First neutrino interaction candidates at the LHC [open], Physical Review D (DOI: 10.1103/PhysRevD.104.L091101)

From New Atlas:

Neutrinos are elementary particles that are electrically neutral, extremely light and rarely interact with particles of matter. That makes them tricky to detect, even though they're very common – in fact, there are billions of neutrinos streaming through your body right now. Because of this, they're often described as ghost particles.

Neutrinos are produced in stars, supernovae, quasars. radioactive decay and from cosmic rays interacting with atoms in the Earth's atmosphere. It's long been thought that particle accelerators like the LHC should be making them too, but without the right instruments they would just zip away undetected.

And now that "right instrument" has been installed and tested. During a pilot run of an experiment called FASER, installed in 2018, scientists picked up six neutrino interactions.

"Prior to this project, no sign of neutrinos has ever been seen at a particle collider," says Jonathan Feng, co-author of a study describing the results. "This significant breakthrough is a step toward developing a deeper understanding of these elusive particles and the role they play in the universe."


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  • (Score: 4, Interesting) by PiMuNu on Monday November 29 2021, @09:11AM (11 children)

    by PiMuNu (3823) on Monday November 29 2021, @09:11AM (#1200462)

    Just in case anyone didn't notice it, the weight of the detector is significant because neutrino interaction rate is proportional to weight, to a good approximation.

    TDR: https://arxiv.org/abs/2001.03073 [arxiv.org]

    Looks like they are just interested in "cross-checking neutrino physics makes sense at higher energy" with no very specific goals beyond that.

    • (Score: 2) by janrinok on Monday November 29 2021, @10:35AM

      by janrinok (52) Subscriber Badge on Monday November 29 2021, @10:35AM (#1200467) Journal

      I wasn't aware of that relationship - thank you.

    • (Score: 2) by FatPhil on Monday November 29 2021, @03:37PM (7 children)

      by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Monday November 29 2021, @03:37PM (#1200548) Homepage
      Yebbut https://upload.wikimedia.org/wikipedia/commons/5/57/FirstNeutrinoEventAnnotated.jpg from https://en.wikipedia.org/wiki/Neutrino#Direct_detection

      In the 20 July 1956 issue of Science, Clyde Cowan, Frederick Reines, Francis B. "Kiko" Harrison, Herald W. Kruse, and Austin D. McGuire published confirmation that they had detected the neutrino,[22][23] a result that was rewarded almost forty years later with the 1995 Nobel Prize.[24]
      ...
      The first detection of tau neutrino interactions was announced in 2000 by the DONUT collaboration at Fermilab; its existence had already been inferred by both theoretical consistency and experimental data from the Large Electron–Positron Collider.[28]

      How is this a first detection?
      --
      Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
      • (Score: 3, Informative) by PiMuNu on Monday November 29 2021, @05:37PM (6 children)

        by PiMuNu (3823) on Monday November 29 2021, @05:37PM (#1200601)

        It is the first detection of neutrinos produced directly *in a collider*.

        The point is that it enables a reasonably high flux of neutrinos having fairly large energies. Largest naturally occurring neutrino energies are ~ MeV, produced in nuclear fusion/fission and from interaction of cosmic rays with the earth's atmosphere. Exception: there are a handful of rare ultra-high energy events detected in IceCube experiment. Largest artificially produced neutrino energies are ~ GeV, like those produced at JPARC for T2K experiment. In this experiment they expect ~ 1000s of > 1 TeV events.

        To inform/remind what the different energy scales mean in terms of accessible science:

        atomic binding energies, conventional chemistry, xrays ~ eV to keV (1-10^3)
        nuclear binding energies, nuclear physics ~ MeV (10^6)
        strange, charm quarks, tau ~ GeV (10^9)
        top, bottom quarks, weak bosons, Higgs ~ 100 GeV (10^11)
        ?Nothing? ~ 1 TeV

        One can then cross-check that neutrino physics works as expected in this new energy regime.

        • (Score: 2) by FatPhil on Tuesday November 30 2021, @07:34AM (5 children)

          by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Tuesday November 30 2021, @07:34AM (#1200807) Homepage
          How is a bubble chambre not a particle collider? That's their sole raison d'etre - you accelerate particles, and collide them with ones that will leave a mark you can photograph. That was particle physics in 1970.
          --
          Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
          • (Score: 2) by PiMuNu on Tuesday November 30 2021, @09:58AM (4 children)

            by PiMuNu (3823) on Tuesday November 30 2021, @09:58AM (#1200815)

            No, a particle collider is made from two opposing beams. The resultant collision products are then collected in a detector surrounding the interaction point.

            A fixed target experiment is completely different.

            • (Score: 2) by FatPhil on Tuesday November 30 2021, @11:33AM (3 children)

              by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Tuesday November 30 2021, @11:33AM (#1200820) Homepage
              Someone should tell SLAC this news, they've been getting it wrong since the 60s.
              --
              Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
              • (Score: 2) by PiMuNu on Tuesday November 30 2021, @11:50AM (2 children)

                by PiMuNu (3823) on Tuesday November 30 2021, @11:50AM (#1200821)

                You are very confused. PEP at SLAC was an e+e- collider, not a fixed target experiment, and is now a light source. From wikipedia:

                https://en.wikipedia.org/wiki/SLAC_National_Accelerator_Laboratory#Stanford_Linear_Collider [wikipedia.org]

                "
                Stanford Linear Collider
                The Stanford Linear Collider was a linear accelerator that collided electrons and positrons at SLAC.
                "

                From wikipedia

                https://en.wikipedia.org/wiki/Collider [wikipedia.org]

                "
                Collider
                A collider is a type of particle accelerator which brings two opposing particle beams together such that the particles collide.
                "

                Or CERN

                https://home.cern/science/accelerators/large-hadron-collider [home.cern]

                "
                Inside the accelerator, two high-energy particle beams travel at close to the speed of light before they are made to collide.
                "

                You are verging on trolling.

                • (Score: 2) by FatPhil on Tuesday November 30 2021, @12:01PM (1 child)

                  by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Tuesday November 30 2021, @12:01PM (#1200822) Homepage
                  No, I'm just confused.

                  The developments of and discoveries from Linacs and Linear Colliders overlapped, and I think I had just presumed that all linear things were things with a target at the end. Add to that the fact that "collider" was in use before most of the big name particle accelerator facilities were up and running, I had just presumed that anything that was colliding anything with anything was a collider.

                  Sometimes, I do think that scientists don't chose the best terms for their jargon, and this could be considered an example. Not as bad as botanists and their "nuts", but still, the choice of term has completely overlooked that the different thing about beam-beam collisions is the symmetry in the momentum, and that it's two beams colliding; in *no way* does "collider" imply "no fixed target" in English. But the mistake was wholly mine. Thanks for your patience.
                  --
                  Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
                  • (Score: 2) by PiMuNu on Tuesday November 30 2021, @01:22PM

                    by PiMuNu (3823) on Tuesday November 30 2021, @01:22PM (#1200838)

                    No problem, sorry for getting cranky!

    • (Score: 0) by Anonymous Coward on Tuesday November 30 2021, @12:34AM (1 child)

      by Anonymous Coward on Tuesday November 30 2021, @12:34AM (#1200747)

      So neutron stars should be pretty effective at stopping neutrinos

      • (Score: 2) by fraxinus-tree on Tuesday November 30 2021, @08:19AM

        by fraxinus-tree (5590) on Tuesday November 30 2021, @08:19AM (#1200811)

        Indeed they are. And as physics goes, they are pretty good at emitting neutrinos as well. Thermal neutrinos are important in the neutron star dynamics, at least for factory-new neutron stars.

  • (Score: 0) by Anonymous Coward on Monday November 29 2021, @04:30PM

    by Anonymous Coward on Monday November 29 2021, @04:30PM (#1200572)

    about as usefull as poltergeists. at least these are now explained by the standard model too, even if they're even less usefull then waste heat...

  • (Score: 0) by Anonymous Coward on Tuesday November 30 2021, @08:54PM

    by Anonymous Coward on Tuesday November 30 2021, @08:54PM (#1200976)

    A large group of neutrinos were picketing outside the Large Hadron Collider with signs saying "Half Lives Matter".

    --
    These signs have now been detected.

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