Radiation: The process of emitting energy in the form of waves or particles.
Where does radiation come from?
Radiation is generally produced when particles interact or decay.A large contribution of the radiationon earth is from the sun (solar) or from radioactive isotopes of the elements (terrestrial).
Radiation is going through you atthis very moment!
What’s an isotope?
Two or more varieties of an element having the same number of protons but different number of neutrons. Certain isotopes are “unstable” and decay to lighter isotopes or elements.Deuterium and tritium are isotopes of hydrogen. In addition to the 1 proton, they have 1 and 2 additional neutrons in the nucleus respectively*.
Another prime example is Uranium 238, or just 238U.
Note: This is theatomic weight, whichis the number ofprotons plus neutronsAlpha Particles (a)
The alpha-particle(a) is a Helium nucleus. It’s the same as the element Helium, with the electrons stripped off !
We see that one of the neutrons from the C14 nucleus “converted” into a proton, and an electron was ejected. The remaining nucleus contains 7p and 7n, which is a nitrogennucleus. In symbolic notation, the following process occurred:
n p + e ( + n )
Yes, the same neutrino we saw previously
In much the same way that electrons in atoms can be in an excited state, so can a nucleus.
10 neutrons(in excited state)
10 neutrons(lowest energy state)
A gamma is a high energy light particle.
It is NOT visible by your naked eye because it is not in the visible part of the EM spectrum.
The gamma from nuclear decayis in the X-ray/ Gamma ray part of the EM spectrum(very energetic!)
* m = E / c2
% of atomsremaining
1 hour (one lifetime) ?
2 hours (two lifetimes) ?
3 hours (three lifetimes) ?
N0 = starting number of particlest = particle’s lifetime
This is the “exponential”. It’s value is 2.718, and is a very usefulnumber. Can you find it on yourcalculator?
Note by slight rearrangement of this formula:
Fraction of particles which did not decay: N / N0 = e-t/t
After 4-5 lifetimes, almost all of the
unstable particles have decayed away!
What if we only have 1 particle before us? What can we sayabout it?
Survival Probability =N / N0 = e-t/t
Decay Probability = 1.0 – (Survival Probability)