Neutrinos are extremely small subatomic particles, often referred to as “ghost particles,” with the ability to pass through the Earth and the human body. Approximately 100 trillion neutrinos pass through the human body harmlessly every second.
Neutrinos are the most abundant subatomic particles in the universe. They can pass through everything and rarely interact with other matter. Consequently, detecting neutrinos is extremely challenging, (subatomic particles are significantly smaller than atoms).
Illustration of neutrino particle traces – (Image: FERMILAB BUBBLE IMAGE)
According to researchers, neutrinos play a crucial role in the Standard Model of particle physics, stellar physics, black holes, and even cosmology and the nature of cosmic explosions.
Scientists from the European Organization for Nuclear Research (CERN) in Switzerland have utilized the Large Hadron Collider (LHC) to investigate the mass of neutrinos.
The experiments indicated that neutrinos are similar to electrons but are electrically neutral and have an extremely small mass, nearly zero. So much so that scientists have hypothesized that neutrinos might even be massless.
In 1955, physicists Clyde Cowan and Frederick Reines from the Los Alamos National Laboratory (the largest multidisciplinary research institute in the United States) led a research team that first discovered neutrinos.
Neutrinos originated from the beta decay process inside a nuclear reactor at the Savannah River Site in South Carolina.
The first “natural” neutrinos were discovered in 1965 in an experiment conducted deep underground at a gold mine in South Africa.
However, it wasn’t until their discovery at the famous Homestake Mine that neutrinos gained significant attention.
The Homestake Mine, located in South Dakota (USA), was the largest gold mine in the United States. Physicists John Bahcall and Ray Davis, Jr. built a laboratory there at a depth of 1,478 meters underground and detected neutrinos from the core of the Sun.
The experiment had to be conducted at such depth to shield against cosmic rays that could affect the results.
However, the results at Homestake posed a significant problem as the number of neutrinos detected was lower than expected—only one-third of the predicted neutrinos were coming from the Sun.
Subsequent neutrino detectors, such as Super-Kamiokande in Japan, also confirmed these findings.
Physicists Bahcall and Davis were awarded the Nobel Prize in Physics in 2002 for their discovery.
Experiments have shown that neutrinos are produced within nuclear reactors on Earth and through nuclear fusion reactions inside the Sun.
However, neutrinos are also “produced” in much more distant locations. In February 1987, a star exploded as a supernova, visible to the naked eye. However, 2-3 hours before the visible light from the supernova reached us, a burst of neutrinos was detected coming from the dying star. This marked the first time neutrinos were detected from a supernova.
Since then, neutrinos have also been detected from events surrounding active supermassive black holes.
Neutrinos are also related to cosmology, as primordial neutrinos formed in the first second after the Big Bang are also prevalent in the universe.
Looking further into the future, scientists hope to establish a neutrino laboratory in the Pacific Ocean. This would be a massive neutrino detector located at least 3.2 kilometers deep.
Neutrinos are among the most closely guarded secrets of the universe, and we are only just beginning to uncover some of their mysteries.
