In beta minus the result is one neutron in the nucleus changing to a proton, plus an electron and an anti-neutrino being sent off.
The antineutrino is indifferent to our health. So I guess what makes a beta source dangerous compared to a cathode ray tube must be a difference in the kinetic energy of the emitted electrons?
Best Answer
Modest energy electrons (such as those found in CRT televisions and monitors) range out (i.e. dump all their energy and stop) very quickly in dense materials like glass, so these tubes are not emitting significant numbers of electrons and those that penetrate are even lower in energy.
In fact they do emits small quantities of soft x-rays do to electron interactions with the material, but again the rate is low and the energy is minimal so there is little penetration.
You probably don't want to sleep on an operating CRT, but watching television subjects you to a infinitesimal dose. (And the allowed dose is regulated throughout the industrialized world.)
We can use the online interface to PSTAR to quantify the range TVs runs at a few tens of thousands of volts, meaning the electrons get, say 30,000 eV = 30 keV = 0.03 MeV, so the penetration is around $10^{-4}\text{ g/cm^2}$, which given that the density of glass is about 2.5ish we get a range of $4\times 10^{-5}\text{ cm}$.