A ghost particle is actually a neutrino which was called like that because it is electrically neutral and its rest mass is so small that it was believed to be zero. Because neutrinos have weak gravitational interaction and do not participate in strong interactions, they can pass through ordinary matter unobstructed and undiscovered. An interesting fact about them is that neutrinos can be found in a large number in the cosmos.
There are various ways with the help of which scientists can detect them. For example, there is the Cherenkov neutrino detector, the Coherent Recoil Detector, scintillators, radio detectors, tracking calorimeters, and also the radiochemical methods. But all these methods can only detect the effect neutrinos have while passing through matter and not the neutrinos.
Determining the mass of a particle that almost has no mass is not that easy. But a team of researchers came with an innovative way to measure the mass of a ghost particle: they used the Universe, or more specifically data collected while studying the Universe.
Scientists finally measured the mass of a ghost particle, or neutrino
The scientists linked the data with input from particle accelerators and were able to make quite an exact measurement of a neutrino. The data collected from the universe is comprised of radiation from exploding stars and of the first light of the Universe and maps of galaxies. They also gathered data from particle accelerators and nuclear reactors.
Because neutrinos come in three different ‘flavors’ (electron, muon, and tau), their mass is hard to determine as these ‘flavors’ oscillate. The enormous volume of data gathered was introduced into a very powerful computer called ‘Grace,’ which made the calculations for the researchers.
Finally, Grace came up with an answer: the lightest ghost particle of the three neutrinos was 0.086 electron volts (1.5 x 10-37 kg). The integrated mass of the three neutrinos is 0.26 electron volts. These are significant findings as, in the future, scientists will be able to make measurements further to find the masses for the other two neutrinos.