Talk:Sudbury Neutrino Observatory

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Contents 1 Location 2 Flux? 3 Where do the oscillations take place? 4 Is it really "solved"?

[edit] Location

The mine is not "near" Greater Sudbury; it is in Greater Sudbury. Bearcat 04:56, 12 May 2005 (UTC)

[edit] Flux?

What is the observed neutrino flux in this detector, in neutrinos per day? What fraction is solar, atmospheric, cosmological? If a supernova happened in our galaxy, what would the be expected number of detected neutrinos? What if in another galaxy? linas 03:38, 14 Jun 2005 (UTC)

Very roughly 20 solar neutrinos per day, one atmospheric neutrino every ten days, one relic supernova neutrino every twenty years. Supernova 1987A would have produced several dozen events, a closer supernova would produce thousands. Flying fish 07:32, 24 November 2005 (UTC)

Thanks! Could I convince you to add a section of this sort to the article? To me, at least, having a feel for the numbers like this gives a much better idea of what is possible and what is not. linas 16:42, 25 November 2005 (UTC)

[edit] Where do the oscillations take place?

This article says that neutrinos change types as the neutrinos travel through the sun. The Solar neutrino problem article says that they change types along the way to Earth. Someone please fix this inconsistency. Ken Arromdee 02:12, 22 August 2005 (UTC)

Fixed. linas 03:47, 22 August 2005 (UTC)

This should not have been "fixed". The neutrinos do change on their way to the Earth from the core of the sun, but almost all of the oscillation occurs inside of the sun as the solar density changes, through the MSW effect. Flying fish 07:32, 24 November 2005 (UTC)

Thanks for re-fixing this. However, the answer you give above is more precise and correct than the statement in the article. Again, I encourage you to add this to the article. And create an article on the MSW effect if that suits you... linas 16:42, 25 November 2005 (UTC)

[edit] Is it really "solved"?

The article claims that SNO detects a number of neutrinos that is on par with that predicted by the standard model (of solar interactions, not the other one). However, this page states that SNO detects about 20 events from the sun a day. Is this the predicted amount that one would expect? It sounds low, at least in comparison to the numbers I seem to remember being bandied about before construction started.

Using the numbers here, it implies that about 12 of the detected neutrinos are muon or tau flavors. Yet due to the fact that the oscillation is time dependant as the detector moves from facing the sun to facing away, this number changes in a statistically significant way. So why was it not possible to "solve" the problem in the past using a "normal" electron flavour detector and looking for this change? Or is this how SK did it?

Maury 12:23, 28 June 2006 (UTC)

I'm not quite sure what you mean that the oscillation is time dependent. For one thing the oscillations take place inside of the sun, and that's not changing too much. For another thing, the detector is just a big tank of water, regardless of whether it is on the side of the Earth facing the sun or the opposite side it can't really be said to be "facing" the sun. The experiment has searched for "day-night" effects which could presumably be caused by the neutrinos passing through the matter of the Earth but all such measurements have been consistent with no day-night effect.

What makes the problem "solved" is that the detector can simultaneously measure the flux of all three neutrino flavours through the neutral current interaction and the electron flavour through the charged current interaction. The flux of all three types is consitent with that predicted by the standard solar model and the flux of electron type neutrinos is greatly suppressed. Flying fish 04:42, 9 July 2006 (UTC)