After an extended and thorough search at the South Pole using a particle detector, scientists are almost certain that the sterile neutrino does not exist. This result comes in spite of a collection of hints and clues of the existence of such a particle resulted from various experiments.
A neutrino is one of the fundamental particles of the universe. They similar to electrons but they don’t carry an electric charge and are only affected by the weak sub-atomic force and gravity. Thanks to these characteristics, they are able to pass through all sorts of matter even humans. There are currently three known types of neutrinos: electron, muon, and tau depending on the charged particle they relate to.
The existence of a sterile neutrino could have led to a complete rethinking of the Standard Model of particle physics, which establishes how subatomic particles interact with one another. But the study published in the scientific journal Physical Review Letter by a team of researchers from the Niels Bohr Institute found that the sterile neutrino has a very low chance of actually being real.
The research team examined thousands of neutrinos in the IceCube Neutrino Observatory using a large particle detector embedded in the ice of the South Pole. According to Francis Halzen, a physics professor at the University of Wisconsin-Madison and the leader of the research team:
“Sterile means it doesn’t interact with matter itself, although it can dramatically interfere with the way conventional neutrinos do.”
Since the theoritical neutrino could not be detected directly, the scientists’ only hope was to observe as it was in the process of interfering with other particles and transforming into another type (flavor) of neutrino. They analyzed neutrinos formed when cosmic rays collide with particles in the Earth’s atmosphere. Sterile neutrinos were thought to form after normal ones pass through dense matter such as the Earth’s core.
After an extended analysis of two independent sets of data, each consisting of around 100, 000 neutrino events and, the research team did not find any evidence for the theoretical sterile neutrino. Though, the lack of evidence from even this type of thorough search isn’t enough to convince scientists to abandon their efforts. It just means that there’s a chance that sterile neutrinos are actually extremely elusive.
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