The cryostat at the centre kept the germanium-76 target cold. This process, called β-decay, also shoots out either an electron or its antiparticle - collectively known as β-particles.Ī man standing in the water tank of the LEGEND-200 experiment. Neutrinos or antineutrinos are created whenever a proton in an unstable atomic nucleus decays into a neutron, or vice versa. In 2015, an advisory committee to the US Department of Energy identified such a project as a priority and a commitment to fund an experiment to detect Majorana neutrinos - estimated to cost around US$250 million - is thought to be imminent. Physicists have looked for the disappearance of neutrinos for decades, but the search is now ramping up dramatically, meaning that they “have a really good shot” at detecting it with the next generation of devices, says Michelle Dolinski, an experimental physicist at Drexel University in Philadelphia, Pennsylvania.Įxperiments now online or being built in Japan, South Korea, Italy, Canada and the United States are an order of magnitude more sensitive than the previous generation, and planned future detectors would improve on that by another two orders of magnitude (see ‘Experiments around the world’). Moreover, they would prove that unlike all other known particles of matter, such as electrons or quarks, neutrinos don’t get their mass from the Higgs boson. Such ‘Majorana neutrinos’ could be the key to understanding why the Universe seems to contain very little antimatter (see ‘Questions that could be answered if neutrinos are Majorana particles’). The phenomenon of disappearing particles would suggest that neutrinos and antineutrinos, their antimatter counterparts, are one and the same - a possibility that Majorana first theorized 1 in the 1930s. These experiments have received less funding or attention than efforts to detect dark matter, but their impact across physics could be just as significant. Several new or upgraded experiments around the world are racing to show that an extremely rare kind of nuclear decay that normally produces two neutrinos might occasionally yield none. His favourite elementary particles, neutrinos, might be capable of a similar vanishing act. Italian physicist Ettore Majorana notoriously disappeared in 1938 without leaving a trace. The SNO+ detector under construction in Sudbury, Canada.

Neutrino particle