How quickly do neutrinos change flavor? DOE’s Fermilab has switched on its newly upgraded neutrino beam. This is in preparation for the NOvA experiment, which will study neutrinos using a 200-ton particle detector at Fermilab and a 14,000-ton detector in northern Minnesota. Story here.
This experiment is to test "flavor changes" in neutrinos. What does current theory predict in terms of flavor changes?  Ie. does a electron neutrino change to a muon neutrino every so many milliseconds?  
 A: You may check the Wikipedia page for neutrino oscillations

https://en.wikipedia.org/wiki/Neutrino_oscillations

where you may also find the derivation of the formula for the neutrino oscillations in the case of two flavors (in which case the oscillations are harmonic and simple)
$$ P_{\alpha\rightarrow\beta, \alpha\neq\beta} = \sin^{2}(2\theta)\, \sin^{2} \left(\frac{\Delta m^2 L}{4E}\right)\quad \mathrm{(natural\,units)} $$
Numerically, in SI units, that is
$$ P_{\alpha\rightarrow\beta, \alpha\neq\beta} = \sin^{2}(2\theta) \, \sin^{2}\left( 1.267 \frac{\Delta m^2 L}{E} \frac{\rm GeV}{\rm eV^{2}\,\rm km}\right). $$
You may see that the probability depends on the length $L$ in kilometers – you may write $L=ct$ using the time $t$ as well, if you wish, $c$ is the speed of light (their speed is undetectably different from $c$). However, the frequency also depends on the neutrino energy $E$ expressed in ${\rm GeV}$ above.
The factor $\Delta m^2$ is the difference between the eigenvalues of $m^2$. For the three species, these are
$$\Delta m_{12}^2 = 7.59\times 10^{-5} {\rm eV}^2$$
$$\Delta m_{32}^2 \approx \Delta m_{13}^2 = 2.32 \times 10^{-3}{\rm eV}^2$$
Two of the neutrino mass eigenvalues are very close to each other. This results in very slow oscillations (solar oscillations, $12$). The remaining third eigenvalue is further from them and it results in faster oscillations (seen in atmospheric oscillations, $23$).
At any rate, the units in the formula above are designed so that $E$ is of order one (i.e. GeV). Because $\Delta m^2$ is 3-5 orders of magnitudes smaller than 1, $L$ of the wavelength is of order between thousands and millions of kilometers which translates roughly to something between milliseconds and seconds. You may calculate the precise frequency for yourself – the periodicity is proportional to the neutrino energy. 
Most of these things have been known for a few decades. What was observed in the last year was a matrix element that allows the $13$ transmutation "directly". The previous solar and atmospheric oscillations de facto measured the angles and mass differences $12$ and $23$ only. The accuracy of all the parameters is rather close to one percent these days.
