13 physical properties of photons
Zero mass, zero rest mass, indirectly ionizing (photons liberate charged particles, which directly ionize)
2 A photon scatters off a free or bound single electron
compton scattering
3 A bound electron absorbs all the energy of the incident photon(hv(o))
Photoelectric effect
4 A positron electron pair is created from a photon in the field of a nucleus
Pair production
5 A photon scatters elastically off a single bound electron so that the entire atom recoils in order to conserve momentum
Rayleigh scattering
6 A photon scatters elastically off a nucleus
Thomson Scattering
7 A nuclear reaction is initiated by a photon
Nuclear resonant scattering
8 What is the importance of photon interactions?
1. lead to the liberation of charged particles which can be collected(detection) 2. describe a photons attenuation in matter(protection-shielding) 3.describe the energy deposition in matter(biological effects-dose)
9 The resulting energy of the photo electron is _______ to the energy of the incoming photon _____ the binding energy for the orbital electron that was ejected as a result of the PE interaction (E=hv-BE)
equal, less
10 Interaction probability (cross-section) __________ with energy and with Z squared
increases
11The fraction of a beam of photons that is absorbed or scattered per unit thickness of the absorber
photon interaction probablity
12 Are classified, according to their mode of origin, not their energy
Photons
13 Are electromagnetic radiation that accompanies nuclear transitions
Gamma rays
14 Also, called continuous x-rays are the results of the acceleration of free electrons or other charged particles
brensstrahlung
15 Are emmitted in atomic transitions of bound electrons between K,L,M shows in atoms
characteristic xrays
16 Is emitted whenever a positron an electron combine
annihlation radiation
17 Interactions involving the photons with energy 0.01 < E < 10 MeV can be described using:
Compton effect, photoelectric effect or pair production
18 Involves the deflection of the incident photon
scattering
19 The scattering angle of compton is dependent on the ___________
incident photon energy
20 The probability of compton interaction is dependent on __________
photon energy
21 The average distance a photon will travel before interacting with the absorber medium and is equal to one over mu centimeters
mean free path