Mass of the Neutrino (eventually)
May. 24th, 2025 11:05 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
jaycrosscdaUnrelated to CdA, but of interest to me:
The neutrino has a small mass (or maybe no mass at all, but that seems unlikely). Experiments and observations have shown that their mass (well, average mass of all three flavors) must be less than 2 millionths the mass of an electron, but newer more cantilevered approaches are showing it is probably at least a thousand times, and maybe a hundred thousand times lighter than even that.
Recently (several months ago) there was a high energy neutrino detected that was coincident with a gravitational wave detection, and maybe a gamma ray burst, with the neutrino delayed several minutes during its journey of billions of light years (possibly not from the same event). Since we knew the energy of the neutrino to a reasonable precision, and the distance to the source, and the length of the delay, we should have been able to determine the mass of the neutrino. Note that if the mass of the neutrino is in the milli-eV range, that delay should only be a fraction of a millisecond for PeV neutrinos to tens or hundreds of seconds for the lowest energy detectable with IceCube etc. Eventually as detectors of both types improve, we should build up some real data on this.
More recently I've seen someone show that IF we can find a blazar (quasar with a beam aimed at us) that is being gravitationally lensed by a foreground galaxy cluster, in the future, when we have much larger bottom-of-the-ocean neutrino detector arrays with better directionality capabilities we should be able to see neutrinos lensed into three rings, for the electron, muon, and tau flavors of the neutrinos (each have a different mass), and the radius of these rings will tell us to a high precision the three masses of the neutrino. I hope I live long enough for that result.
Of course, the most direct way would be to collect a mole of these particles and weigh them, but if you try and visualize how you would do this, you'll see that their elusiveness makes that a difficult project.
The neutrino has a small mass (or maybe no mass at all, but that seems unlikely). Experiments and observations have shown that their mass (well, average mass of all three flavors) must be less than 2 millionths the mass of an electron, but newer more cantilevered approaches are showing it is probably at least a thousand times, and maybe a hundred thousand times lighter than even that.
Recently (several months ago) there was a high energy neutrino detected that was coincident with a gravitational wave detection, and maybe a gamma ray burst, with the neutrino delayed several minutes during its journey of billions of light years (possibly not from the same event). Since we knew the energy of the neutrino to a reasonable precision, and the distance to the source, and the length of the delay, we should have been able to determine the mass of the neutrino. Note that if the mass of the neutrino is in the milli-eV range, that delay should only be a fraction of a millisecond for PeV neutrinos to tens or hundreds of seconds for the lowest energy detectable with IceCube etc. Eventually as detectors of both types improve, we should build up some real data on this.
More recently I've seen someone show that IF we can find a blazar (quasar with a beam aimed at us) that is being gravitationally lensed by a foreground galaxy cluster, in the future, when we have much larger bottom-of-the-ocean neutrino detector arrays with better directionality capabilities we should be able to see neutrinos lensed into three rings, for the electron, muon, and tau flavors of the neutrinos (each have a different mass), and the radius of these rings will tell us to a high precision the three masses of the neutrino. I hope I live long enough for that result.
Of course, the most direct way would be to collect a mole of these particles and weigh them, but if you try and visualize how you would do this, you'll see that their elusiveness makes that a difficult project.
Yes ...
Date: 2025-05-24 05:30 pm (UTC)