Researchers captured the outbreak of a tank of pure water buried under miles of rock in Ontario, Canada, when a tiny particle collided through its molecules.
This is the first time that water has been used to detect a particle known as an antineutrino that originated in a nuclear reactor more than 240 kilometers (150 miles) away. This breakthrough promises neutrino experiments and observational technologies that use inexpensive, readily available, and safe materials.
As one of the most common particles in the universe, neutrinos are exotic little things with great potential for a deeper understanding of the universe. Unfortunately, they have almost no mass, no charge, and almost no interaction with other particles. Basically, they flow through space and rocks, as if all matter is intangible, which is why they are called ghost particles.
An antineutrino is an antiparticle analog of a neutrino. Usually, the antiparticle has the opposite charge to the equivalent particle; For example, the antiparticle of a negatively charged electron is a positively charged positron. Since neutrinos carry no charge, scientists can distinguish between them based solely on the fact that an electron neutrino appears next to a positron, while an electron antineutrino appears along with an electron.
Electron antineutrinos are emitted during beta decay, a type of radioactive decay in which a neutron decays into a proton, an electron, and an antineutrino. One of these antineutrino electrons can interact with a proton to form a positron and a neutron, a reaction known as inverse beta decay.
To detect this particular type of decay, large liquid-filled tanks with photomultipliers are used. It was designed to capture the faint glow of Cherenkov radiation produced by charged particles moving faster than light, which can travel through a liquid, similar to a sonic boom caused by breaking a sound barrier.
Antineutrinos are produced in large quantities by nuclear reactors, but they have a relatively low energy, making them difficult to detect.
and enter SNO+. Buried under over 2 kilometers (1.24 miles) of rock, this is the deepest underground laboratory in the world. This rock screen provides an effective barrier against cosmic ray interference, allowing scientists to receive exceptionally high-resolution signals.
Today, the laboratory’s 780-ton spherical tank is filled with linear alkylbenzene, a shimmering light-enhancing liquid. Back in 2018, when the unit was being calibrated, it was filled with highly purified water.
After analyzing 190 days of data collected during this calibration step in 2018, the SNO+ collaboration found evidence for inverse beta decay. The neutron produced during this process is captured by the hydrogen nucleus in the water, which in turn produces a subtle flash of light at a very specific energy level, 2.2 MeV.
Cherenkov water detectors usually have difficulty detecting signals below 3 MeV; But CHO+ filled with water could detect up to 1.4 MeV. This results in an efficiency of about 50% for detecting 2.2 MeV signals, so the team decided that looking for signs of inverse beta decay was worth their luck.
Analysis of the candidate signal determined that it was likely caused by an antineutrino, with a 3 sigma confidence level – a 99.7% probability.
The result shows that water detectors can be used to monitor the power generation of nuclear reactors.
Meanwhile, SNO+ is being used to better understand neutrinos and antineutrinos. Since neutrinos cannot be measured directly, we know little about them. One of the biggest questions is whether neutrinos and antineutrinos are the same particles. This question will be answered by a rare, never seen before dissolution. SNO+ is currently looking for this breakup.
“We are very interested in the possibility of using pure water to measure antineutrinos from reactors at long distances,” says physicist Logan Lipanovski from the SNO + Institute and the University of California at Berkeley. “We have made great efforts to extract just a few signals from 190 days of data. The result is satisfactory. “
The study is published in the journal Physical Review Letters.
Source: Science Alert
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