Neutrino : The Elf Crossing the Earth
On October 6, 2016, Japanese researcher Kaita Takaaki and Canadian researcher Arthur MacDonald made important contributions to the discovery of neutrino oscillation.
So, what is neutrino oscillation?
The key to opening a new world of physics
To understand neutrino oscillation, you must first know the "standard model". In particle physics, this theoretical model is used to describe the individual elementary particles and their interactions. The standard model predicts quark , lepton, etc., especially the Higgs particle, which won the Nobel Prize in the past few years, is the last particle predicted in the standard model.
However, "the head under the crown is always difficult to maintain stability." Shakespeare's words can also be given to today's standard model of particle physics. Although the Standard Model has achieved great success in the past few decades, it also has some small flaws. Just like classical physics in the late 19th century, the Standard Model cannot describe the existence of dark matter , nor can it describe what dark energy is. However, after all, dark matter and dark energy have not been officially discovered, and the Standard Model does not need to be too "worry".
But people were not satisfied, but they were more eager to pull the standard model down and look for new physics chapters that surpassed it. "The standard model is particle physics," said Nobel Prize winner Jack Steinberg, "but many questions are still hopeless to answer."
, and solving these problems requires new matter. Researchers have hoped for Higgs particle , but since the Higgs particle currently performs basically in a normal manner, perhaps the key to a new physical world outside the standard model is not in it, but hiding in another particle: neutrinos.
The elves that will "change face"
Neutrinos are a large number of uncharged fundamental particles in the universe. Like electrons and quarks, they are the basic component units of the universe.
The neutrino has extremely light mass, but has extremely strong penetration. It can cross the intercontinental and even the interstellar world to complete "ultra-long-distance travel". In fact, millions of sun neutrinos are freely penetrating each person's body every second, and neutrinos from other sources can pass through the human body within one second.
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The three types of neutrinos (electron neutrinos, muzi neutrinos and Taozi neutrinos) that are distinguished by different "tastes" are like cunning and changeable spirits. They will constantly transform during flight, transforming from one taste to another - in physics terms, this is called "neutrino oscillation". This wonderful oscillation process carries many mysteries of microscopic world .
neutrino oscillation phenomenon was first discovered by American scientist Davis, the winner of the 2002 Nobel Prize in Physics, in the 1960s. It is currently the only experimental result that directly exceeds the standard model. The standard model requires that the static mass of neutrinos is strictly 0. They must follow the conservation of lepton numbers and cannot be transformed from each other. But the experiment found that neutrinos from different generations can transform into each other, which is the so-called "neutrino oscillation". This phenomenon requires neutrinos to have mass and therefore exceeds the standard model.
Simply put, if an nuclear reactor produces 100 anti-electron neutrinos, when we observe 1 km away, we can only see 95, and the other 5 are converted into muzi neutrinos and Taozi neutrinos.
For example, let’s say that neutrinos are a group of ordinary young people. They went on an outing during the National Day holiday, but when they arrived at the destination, they found that only 1/3 of the people were left, and the other 2/3 disappeared. This is the mystery of the loss of neutrinos. Later, people found that ordinary young people did not lose, but became literary youths and 2B youths, which is called neutrino oscillation.
solves the mystery of antimatter disappearance
At present, neutrinos are a hot research field in particle physics, and are likely to be the breakthrough point of the next generation of physics.my country is already at the forefront of the world in this field: in 2007, my country began to build the Daya Bay neutrino experiment to study neutrino oscillations 2km away from the nuclear reactor; in March 2012, my country measured this oscillation mode for the first time in the world. In
, the micro-word oscillation is carried out according to the laws of sine and cosine. The amplitudes of the three oscillations have been measured, but there are still two frequencies that have not been clearly determined. This is the focus of the next generation of neutrino experiments at home and abroad, including my country's Jiangmen neutrino experiment, Japan's HyperK experiment, the United States' DUNE experiment, and Antarctic IceCube experiment. If this frequency can be measured in the next decade, the next problem of neutrino oscillation is CP destruction, that is, the difference between positive and negative neutrinos, which may explain why there is much more matter in the universe than antimatter.
At present, the research on neutrinos is all research in the field of basic science and has not been applied to daily life. However, as neutrino expert and neutrinos expert and winner of the Asia-Pacific Physics Society, Cao Jun said: "400 years ago, Danish scientist Tycoon looked up at the starry sky for 30 years, accumulated a large amount of astronomical data, which was summarized by his disciples into Kepler's three laws, which became an important basis for Newton to propose Newton's mechanics. Who would have thought that Tyco could see through the stars every day and stare at the stars every day The mystery of planetary motion will become the foundation for us to build tall buildings, bridges, aircraft, cars, and launch spacecraft satellites in 400 years? Today's science will be tomorrow's technology. From basic scientific research to technological transformation, it requires the continuous efforts of generations of scientists."
At present, neutrinos have become a detection tool in astronomy and geology. Supernova explosions will release a large number of neutrinos, and the nuclear decay in the earth will also release neutrinos. These neutrinos will become a new tool for studying astrophysics and geology.
