Physicists have taken a small but significant step toward measuring the qualities of an elusive “ghost particle” known as a ghost particle. neutrino ——This achievement may be achieved in standard model of particle physics.
Precise measurements of neutrino masses will allow physicists to delve deeper into the evolution of the universe and potentially discover new, undiscovered physical phenomena hidden outside the Standard Model. . These particles are well-deserved for their bizarre moniker: They lack electric charge and have almost no mass, which means they fly right through regular matter in close proximity to the particles. speed of light.
So, to get close to the most precise upper limit on neutrino masses, researchers had to design an experiment with unprecedented sensitivity.They report their findings in a paper published April 19 in the journal natural physics.
“For the Airbus A-380, which is the largest payload, you can use this sensitivity to determine if a drop of water has fallen on it,” Christoph SchweigerPhD student at the Max Planck Institute for Nuclear Physics in Germany and first author of the study, said in a statement.
Every second, approximately 100 billion neutrinos pass through every square centimeter of your body. These tiny particles are everywhere – produced in the nuclear fires of stars, in giant supernova explosions, in cosmic rays and radioactive decay, and in particle accelerators and nuclear reactors here on Earth.
In fact, neutrinos were first discovered from nuclear reactors in 1956 and are the most abundant subatomic particles in the universe after photons (light particles).
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In the past, physicists assumed that neutrinos (much like photons) had no rest mass—a fact that made their existence compatible with the Standard Model of particle physics. But this assumption has been challenged by the discovery of neutrinos streaming from the sun, which can randomly switch between the three “flavors” of neutrinos – electrons, muons and tau neutrinos, which are are different particles that interact with neutrinos.
This transformation is only possible if the neutrino has a certain mass, which has led physicists to design complex experiments to measure it.
The ghost on the scale
Technically, the strangeness of the quantum mechanical mixing between the three neutrino flavors means that none of them have well-defined qualities. Rather, they are a combination of three different “states of quality.” This means that physicists are not looking for an exact reading of a neutrino’s mass, but rather an upper limit on that mass.
Nearly 99% of the mass of any object, including our own bodies, comes from the binding energy inside atoms that holds fundamental particles together. However, the remaining 1% of the mass is inherent to these particles.
To find this intrinsic mass, physicists look for something called the Q-value, which is the difference between the sum of the masses of the initial reactants and the sum of the masses of the final products. With this value, further measurements can extract the intrinsic mass from the atom’s total mass.
The Karlsruhe Tritium Neutrino Experiment (KATRIN) in Germany is a neutrino mass measurement experiment. By measuring the energy when superheavy hydrogen decays (therefore, according to Einstein’s E = mc2, that is, the mass difference), it is found A precise estimate of the neutrino mass was obtained.
The best results from the KATRIN experiment found that the upper limit of neutrino mass is 0.8 electron volts, making it about 500,000 times smaller than the mass of an electron.
This measurement can also be done in reverse by watching the artificial isotope holmium-163 capture electrons, convert them into dysprosium-163, and release neutrinos. But to do this, the isotope must be surrounded by gold atoms.
“However, these gold atoms may have an impact on holmium-163,” Schweiger said. “It is therefore important to measure the Q value as accurately as possible using alternative methods” and compare it with the mass value determined by the KATRIN method to detect possible sources of error.
To get closer to an individual measurement of the neutrino’s elusive mass, the researchers designed an experiment called Penantrap, which is a combination of five “Penning traps” that capture atoms within a combination of electric and magnetic fields. They sway in a complex motion known as a “circle dance.”
By placing charged holmium-163 and dysprosium-163 ions into a Penning trap and measuring minute differences in their oscillation rates, physicists measured the difference in energy caused by the extra neutrinos.
The researchers say the Q value measurement is 50 times more precise than any previous experiment. With this result, a better upper limit for neutrino mass is a small, but important, step closer.
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