Neutrinos

[mms]

Hello,

I am new to all of this (Cosmology, TOE, etc), but find it fascinating, and would like to learn more.

Excuse this question if it is a stupid one but...

I have read that billions of neutrinos pass thru a human body every second,
but the Neutrino Observatory in Sudbury detects only in the order of 10 per day...

Can someone please explain this?

[AntonioLao]

neutrinos cannot interact with anything easily as that of other elementary particles. The interaction cross section (area normal to the neutrino flux) is found by experiment to have very small value.

http://prola.aps.org/abstract/PRD/v59/i11/e113005

and the detected number for solar neutrinos is only 1/3 of the predicted value. Scientists theorize this as due to neutrino oscillations between the three types: electron, muon, and tau neutrinos.

[mms]

Thanks Antonio,

So it is not that just 10 are passing thru the detector in any given day,
but rather that just 10 are able to be detected in that period.

[AntonioLao]

I dont know the exact number detected. But you can look at the following website to appreciate the enormity of this kind of endeavor.

http://www.windows.ucar.edu/tour/lin...detectors.html