The basics of the Long-Baseline Neutrino Experiment:
What are we doing? Producing neutrinos and antineutrinos – nearly massless subatomic particles – and aiming them straight through 800 miles of earth and across several state lines.
How do neutrinos get ‘produced’? In a really cool way. Every 1.3 seconds, an accelerator at Fermilab (outside Chicago) will smash a batch of protons into a graphite target to make short-lived pions.
Then what? Strong magnetic fields guide and focus the pions to form a beam that points toward a detector site at Sanford Lab in the Black Hills of South Dakota. The detectors are located in the repurposed Homestake mine, the largest and deepest gold mine of its time.
But pions aren’t neutrinos, right? Not yet, they aren’t. As the pions travel hundreds of feet in just one-hundredth of a second, they decay and produce muon neutrinos and antineutrinos.
How do we detect neutrinos once they get to the mine? A detector chamber holding 10,000 tons of liquid argon awaits their arrival. Designed and built by Brookhaven engineers, this liquid argon detector uses huge refrigeration chambers to keep the argon at minus 303 degrees Fahrenheit in order to keep the sensors absolutely still. Catching the rare interactions between neutrinos and the nuclei of argon atoms takes painstaking precision and a lot of patience.
Why are we doing this? According to our best understanding of the physical universe, the Standard Model, antimatter and matter should exist in equal amounts. But as you can tell by looking around you, we live in a world with much more matter than antimatter. Neutrinos might be the key to figuring out why the universe is filled with matter while antimatter all but disappeared after the Big Bang.
Tell me another cool thing about this project: The Homestake mine is the site of the Nobel Prize-winning Ray Davis solar neutrino experiment. Davis was a Brookhaven researcher who successfully detected solar neutrinos - ghostlike particles from the sun streaming through our planet – and found that there were 1/3 as many neutrinos were produced as predicted. The mystery of the missing neutrinos led to the discovery that neutrinos are shape-shifters that can oscillate into different forms previously undetectable.
Where can I learn more? Our friends over at Symmetry magazine ran this great story about the Long-Baseline Neutrino Experiment, which is where we got that great GIF above.