Name: Krystal C.
During a 45 minute class period, how many neutrinos pass through you?
The flux of neutrinos going through you is about 2 x 10^10/cm^2/sec. (You can find this number
by searching for "solar neutrino flux" on the web.)
Taking your cross section area to be about 500 cm^2 (12.5 cm x 40 cm), this gives the flux
through your body as roughly 10^13/sec. Multiplying by the 45 min * 60sec/min = 2700 sec in a
45 minute class, we arrive at about 2 x 10^16 neutrinos traverse your body during a 45 minute
class. That is 20,000,000,000,000,000 neutrinos!
If your classroom were right next to a nuclear reactor, the neutrino flux would be about 100,000
times greater. Neither number poses any danger to you since neutrinos interact hardly at all.
They go through the entire earth with only a tiny probability to interact.
It is interesting to note that this is comparable to the number of photons (quanta of light)
which strike your body when you are outdoors on a sunny day. This is not surprising, since
both are produced in the same process inside the sun.
Best, Dick Plano, Professor of Physics emeritus, Rutgers University
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Update: June 2012