Using a new highly sensitive spectrometer, an international team of researchers has found a new value for the upper mass limit of elusive neutrino particles. Until recently, it was believed that neutrino particles do not have mass at all, but the results of some studies indicate the fallacy of such a judgment. And, of course, the next logical step should be to determine this mass, and this is done by gradually narrowing the range between the upper and lower limits of this value.
Scientists have long been able to find evidence that mysterious neutrino particles exist in reality, their number, according to assumptions, is a billion times greater than the number of atoms in the universe. However, despite such an abundance of these particles, scientists managed to achieve only insignificant successes in the study of their properties. And these properties should contain a lot of things for our understanding of the physics of processes occurring at the smallest level.
Let’s go back to measuring the neutrino mass. There are currently three different methods for this. The first method uses the analysis of cosmic microwave radiation of the background, in the second method, scientists look for very rare cases of neutrinoless double beta decay of certain elementary particles, and the third method consists in trying direct measurements of neutrino mass by exotic methods that are not based on any of the existing theoretical models.
It was this third method of measuring neutrino mass that was used by scientists working as part of the KATRIN experiment (Karlsruhe Tritium Neutrino Experiment), conducted by researchers from the Karlsruhe Institute of Technology in Germany. The key instrument of this experiment is a huge 200-ton electronic spectrometer, which is used to study the decay of tritium, a radioactive isotope of hydrogen. When tritium decays, it generates a single electron and neutrino at one time. Knowing the initial energy of tritium and measuring the energy of this electron with a highly sensitive spectrometer allows you to calculate the neutrino mass with a sufficiently high accuracy that exceeds the accuracy of previous similar measurements.
The data collected during the experiment indicated that the value of the upper limit of the neutrino mass is 1.1 electron volts, which is approximately half of the value determined previously. And this, one can say, is a very small mass, which is 500 thousand times smaller than the mass of an electron, which also cannot be called a large and heavy particle.