Detectors room

The science of particle detection relies on the interactions that occur when particles encounter matter. When a charged particle interacts with matter, it excites and ionizes molecules along its path. A cloud chamber is a particle detector that uses evaporated alcohol to make a “cloud” that is sensitive to passing particles. When a particle zips through a cloud, it creates tracks (like airplanes do in the sky) that are visible to the naked eye.

High-energy cosmic rays are protons and heavier nuclei of atoms that travel across the cosmos. When they crash into Earth’s atmosphere, they create sprays of secondary particles that rain down on Earth. Thousands of cosmic ray muons (fundamental elementary particles) per minute per square meter arrive at sea level. This shower of subatomic particles passes unnoticed through all kinds of objects, including us, but cosmic ray detectors can detect them.

Neutrinos are the most abundant matter particles in the universe. They have zero electric charge, and they can travel thousands of kilometers in a small fraction of a second. A Neutrino can go through the Earth without a single interaction. Neutrinos come in three types, called flavors. A muon neutrino is always produced with a muon, and an electron neutrino – with an electron. Neutrinos can morph from one type to another – this is called neutrino oscillation. Fermilab builds special neutrino detectors to study these mysterious particles.