Pure Water Can Measure Antineutrinos From Nuclear Reactors at Large Distances
Pure water could be an inexpensive way to detect antineutrino. A recent study showed how it successfully did.
Pure Water Glows After Detecting Antineutrino
In Ontario, Canada, a tank of the purest water buried under miles of rock in 2018 flashed as barely perceptible particles crashed through its molecules. It was the first time a particle called an antineutrino, which came from a nuclear reactor more than 240 kilometers (150 miles) away, has been found in water. This amazing discovery opens the door to neutrino experiments and monitoring devices that utilize low-cost, accessible, and secure materials.
This type of decay is found using large, liquid-filled tanks with photomultiplier tubes lined inside. They are made to record the sonic boom produced by breaking the sound barrier or the faint glow of Cherenkov radiation produced by charged particles traveling faster through liquid than light can travel. They are, therefore, susceptible to very dim light.
Nuclear reactors produce enormous amounts of antineutrinos, but their low energy makes it challenging to detect them.
The SNO+ collaboration discovered evidence of inverse beta decay after going through the 190 days' worth of data gathered during that calibration phase in 2018. A hydrogen nucleus in the water absorbs the neutron created during this process, which causes a delicate bloom of light to appear at a very particular energy level of 2.2 megaelectron volts.
A water-filled SNO+ could detect signals as low as 1.4 megaelectronvolts, whereas most water Cherenkov detectors have trouble picking up signals below three megaelectronvolts.
Since signals at 2.2 megaelectronvolts may be detected with an efficiency of about 50%, the researchers decided it was worthwhile to try and find evidence of inverse beta decay.
An analysis of a potential signal yielded a confidence level of 3 sigma, or a likelihood of 99.7 percent, that an antineutrino most likely generated it. The outcome shows that nuclear reactor power output could be monitored using water detectors.
Back in March 2023, physicist Logan Lebanowski of the SNO+ team at the University of California, Berkeley, admitted that it intrigued them that "pure water can be used to measure antineutrinos from reactors and at such large distances."
What Is Antineutrino?
Antineutrinos are the antiparticle equivalent of neutrinos. An antiparticle often has the opposite charge to that of its particle equivalent; for instance, the positively charged positron is the antiparticle of the negatively charged electron.
Neutrinos are strange, tiny things with much potential for shedding light on the universe in new and profound ways. Sadly, neutrinos have no mass, no charge, and barely interact with other particles. Most of them flow through rock and space similarly, as though all matter were ethereal. They are referred to as ghost particles for a reason.
Neutrinos don't have charges. Therefore, the only way scientists can distinguish between the two is that an electron neutrino will emerge alongside a positron, whereas an electron antineutrino will occur with an electron.
Nuclear beta decay, a form of radioactive decay in which a neutron decays into a proton, an electron, and an antineutrino, emits electron antineutrinos. Inverse beta decay is when one of these electron antineutrinos interacts with a proton to create a positron and a neutron.
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