Invisible Guests from the Accelerator express
In an underground hall at Fermilab, a huge tank holds liquid argon — a transparent fluid at minus 186 degrees. When an invisible neutrino flies into the tank, it occasionally strikes an argon nucleus, and a short track of charged particles flashes. The MicroBooNE detector has been catching such flashes for several years and has accumulated hundreds of thousands of records.
Neutrinos are the most elusive of known particles: they pass through Earth, barely interacting with anything. But in liquid argon, their tracks become visible, like bubbles in a soda when you pop the cap. Scientists dissect each track and count how often different particles are born: ordinary ones, without anything new, or rare ones — for example, kaons or lambda hyperons.
These measurements are not just for curiosity. Neutrinos can change their type on the fly: this is called oscillation. To precisely measure such transformations in the future DUNE experiment, one must know in detail how neutrinos interact with argon. MicroBooNE data are like a dress rehearsal before the big show.
The liquid argon in the MicroBooNE detector is so pure that ionization electrons can travel several meters without getting stuck along the way.
In the series 'The Expanse', neutrino detectors are used for communication through the bulk of asteroids — almost like MicroBooNE catching signals from the beam.