Thursday, October 12, 2017


This week is full of phone conferences. We issued a bulletin announcing a nice very high energy "track-like" event, and this events seems to coincide in direction and time with a gamma ray blazar.

It would be wonderful to be able to associate a neutrino with a known source (it turns out to be rather hard), and the presence of two kinds of messengers (neutrinos and gamma rays) would give hard evidence for some classes of models of what's going on there, and serious challenges to others.

Scuttlebutt holds that the recalculated direction doesn't point as cleanly at the blazar as the first estimates said, but we'll see--probably by the end of the week.

BTW, a muon neutrino produces a muon through a charged current interaction, and that muon track points back pretty well to where the muon neutrino came from. An electron neutrino produces an electron, and that showers very quickly--you get a dramatic amount of light but not much of a track to point with. A tau neutrino--we've apparently had some taus, but it has proved rather hard to distinguish them from the electrons. Some of the time the tau track should shower quickly like an electron, but sometimes we should get a "double bang:" an interaction and shower, followed by a short track and another shower--sort of like a dumb-bell. So far we've not seen the double bang.

No comments: