Neutrinos may possess the intriguing ability to serve as their own antiparticles, raising the possibility that they could transform into antineutrinos and vice versa. This concept, which gains support from the proposed existence of right-handed neutrinos, suggests that neutrinos are fundamentally distinct from other well-known particles such as electrons and quarks. The potential for antineutrinos to convert into neutrinos could shed light on the disappearance of antimatter in the early universe.
A promising method to explore this theory involves seeking out a rare and yet-to-be-observed phenomenon known as “neutrinoless double-beta decay.” In the standard version of double-beta decay, two neutrons in a nucleus decay into protons, resulting in the release of two electrons and two antineutrinos. However, if neutrinos can indeed act as their own antiparticles, they could annihilate each other during this process, leading to the emission of only the two electrons and a significant release of energy.
Several experiments are currently being conducted or planned to investigate this decay, including the KamLAND-Zen initiative at the Kamioka neutrino detection facility in Japan, the nEXO project at SNOLAB in Ontario, Canada, the NEXT experiment at the Canfranc Underground Laboratory in Spain, and the LEGEND experiment at the Gran Sasso laboratory in Italy. Notably, KamLAND-Zen, NEXT, and LEGEND are already operational.
These experiments may vary in their specific methodologies, but they share a common approach. They utilize large containers filled with dense, radioactive materials, equipped with arrays of detectors that seek out the emission of unusually energetic electrons. The absence of expected neutrino counterparts would indicate that the energy typically carried by the neutrinos is instead transferred to the electrons.
The neutrino, often regarded as one of the most enigmatic particles, is gradually revealing its secrets. This unfolding knowledge may help elucidate the mystery of our matter-dominated universe, a universe that nurtures intelligent beings like ourselves. The neutrinos that pass through our bodies every second are increasingly providing insights into the nature of the cosmos.
“We are entering a very exciting era,” states Turner.
This article originally appeared in Knowable Magazine, a nonprofit publication dedicated to making scientific knowledge accessible to all. Sign up for Knowable Magazine’s newsletter.
