If middle school and high school science has taught us anything about particle physics, it’s that atoms are composed of three primary components: protons, neutrons, and electrons. These three particles, when combined in various ways and in varying amounts, make up all the elements of the periodic table, enabling the different necessary chemical reactions that power ourselves and our world.
However, there are a lot more particles out there than just those that make up the atoms in your skin and clothes; in fact, some of the so-called “pieces” of atoms are themselves just a combination of even smaller constituents—so small that they instead operate on the realm of quantum physics, thus “living” by a slightly different set of rules.
While not participatory in any nearby protons or neutrons, neutrinos are themselves a bit of a mystery, even to quantum physicists. These oddball subatomic particles, together with electrons, the quarks that form your favorite protons and neutrons, and the rest of their complicated family, form the backbone of reality that we call the Standard Model of particle physics.
As the name suggests, neutrinos are neutral in charge, much like their much bigger neutron cousins; that means they don’t really feel like following the rules set by any nearby electromagnetic fields. These neutrinos also possess mass, although they are so small that most physicists once thought they were actually massless.
In short, these neutrinos are subatomic particles that are difficult to detect, and are impossible to observe with just visible light. In fact, the Sun is our primary source of neutrinos; it produces so much that there are about 65 billion neutrinos that pass through every square centimeter of our planet’s surface every second—yet both we and our detectors barely feel a thing. This is the reason why these particles bear the nickname of “ghost particles.”
The world of particle physics may be in for a shake-up, however, given the recent reports from the world-famous Large Hadron Collider (LHC), which made headlines nearly a decade ago for reporting the detection of the long-predicted Higgs boson. The facility’s FASERnu (Forward Search Experiment) neutrino subdetector recently announced that it had detected these elusive neutrinos for the first time, with their findings published in the journal Physical Review D.
“Prior to this project, no sign of neutrinos has ever been seen at a particle collider,” said FASER Collaboration co-head Jonathan Feng, from the University of California Irvine (UCIrvine). “This significant breakthrough is a step toward developing a deeper understanding of these elusive particles and the role they play in the Universe.”
FASERnu is actually one of nine current particle physics experiments at the LHC, and is a type of detector known as an emulsion detector. They are called as such due to the use of emulsion layers, sandwiched between layers of lead (Pb) and tungsten (W) plates. Scientists hope that passing neutrinos collide with the lead and tungsten atomic nuclei, which then hopefully produce particle by-products that leave tracks within the emulsion not dissimilar to bullets traveling through layers of bulletproof glass.
While there are other neutrino detector facilities out there, ones like those within the LHC are special due to the fact that they specifically target neutrinos produced by the accelerator, which have been difficult to detect thus far. This makes the landmark find by the FASER Collaboration the first of its kind in the world.
Said FASER co-head David Casper, who’s also from UCIrvine: “Given the power of our new detector and its prime location at CERN, we expect to be able to record more than 10,000 neutrino interactions in the next run of the LHC, beginning in 2022. “We will detect the highest-energy neutrinos that have ever been produced from a human-made source.”
As of now, the FASERnu neutrino detector scientists hope to work their way up in order to hopefully detect and measure physical phenomena at the cutting edge of physics, such as dark matter.
References
- FASER Collaboration, Abreu, H., Afik, Y., Antel, C., Arakawa, J., Ariga, A., Ariga, T., Bernlochner, F., Boeckh, T., Boyd, J., Brenner, L., Cadoux, F., Casper, D. W., Cavanagh, C., Cerutti, F., Chen, X., Coccaro, A., D’Onofrio, M., Dozen, C., … Zhang, G. (2021). First neutrino interaction candidates at the LHC. Physical Review D, 104(9), L091101. https://doi.org/10.1103/PhysRevD.104.L091101
- Irving, M. (2021, November 26). ‘Ghost particles’ detected in the Large Hadron Collider for first time. New Atlas. https://newatlas.com/physics/neutrinos-large-hadron-collider-faser/
- Starr, M. (2021, November 29). Physicists detect elusive ‘ghost particles’ in the lhc for the very first time. ScienceAlert. https://www.sciencealert.com/for-the-first-time-neutrinos-may-have-been-detected-at-the-large-hadron-collider
