B Speed of neutrinos - latest results?

[Vanadium 50]

We have never seen a neutrino from a supernova. We have only seen antineutrinos.

Neutrinos have a short emission time - a time scale of tens of milliseconds. Antineutrinos have a time scale of tens of seconds.

So a nearby galactic supernova would be 1000x better than 1987a? Not exactly - while we know the start time ~1000x better, it would also be ~1000x closer,. so the time difference is ~1000x smaller. And we're right back where we were. Maybe we'll do two or four times better, but not a thousand.

 

[ohwilleke]

Is the idea that the higher energy neutrinos will be faster. Then if we can detect the pulses and the model for timing of the pulse origin is correct we can then calculate the rest mass. I suppose the problem is that at highly relativistic speeds the difference in velocity is tiny. Well, it's not my problem. Let someone else earn their PhD doing this.

The idea is that neutrinos get spewed out in advance of the the explosion itself fully manifesting in a particular pattern, and you need to model the process properly to make meaningful comparisons of different signals arriving from a distant source. You also need to model properly different routes that the neutrino could have taken to get from the source to Earth where it is detected.

 

[ohwilleke]

We have never seen a neutrino from a supernova. We have only seen antineutrinos.

True but pretty pedantic. Obviously, in this context, one is talking about both neutrino and antineutrino observations when one is talking about what neutrino telescopes on Earth are seeing.

Neutrinos have a short emission time - a time scale of tens of milliseconds. Antineutrinos have a time scale of tens of seconds.

So a nearby galactic supernova would be 1000x better than 1987a? Not exactly - while we know the start time ~1000x better, it would also be ~1000x closer,. so the time difference is ~1000x smaller. And we're right back where we were. Maybe we'll do two or four times better, but not a thousand.

This tradeoff is indeed a big deal and creates a sweet spot that is not too near and not too far.