Interactions with Matter (2)

Question 1

Define Attenuation

Answer 1

Loss of energy

Question 2

Three process of attenuation from x and gamma radiation

Answer 2

• Photoelectric process
• Compton scattering
• Pair producing

Question 3

Photoelectric Process

Answer 3

Incident photon of low energy transfers all energy (complete absorption) to an electron part of an atom upon collision.

if photon energy is more than required to eject the electron, excess energy will transfer to the electron in the form of kinetic energy, creating a “photoelectron” (able to affect/expose photographic film)

Question 4

Compton Scattering

Answer 4

Incident photon of medium energy collides with an electron in an atom, dislodging it. Photon energy is greater than required to eject the electron and the photon will continue to travel in a different direction (secondary/scattered radiation)

Question 5

Pair Production

Answer 5

Incident Photon (1.02MeV) interacts with an atoms nucleus, annihilating the photon, creating an electron (-1) and a positron (+1). any extra energy is transferred to particles as kinetic.

positron combines with a free electron, creating two photons of 0.51MeV each.