TLO 5 Radiation Emitted

Question 1

ELO 1 Describe Charged Particle Interaction

Answer 1

Charged particles have surrounding electrical fields that interact with the medium through which they are traveling by accelerating surrounding atoms’ electrons until those electrons escape from their atoms causing ionization.
*Directly causes ionization

Question 2

ELO 1 Describe Uncharged Particle Interaction

Answer 2

Uncharged particles do not have an electrical field. They can only cause ionization by direct collisions or scattering.
*Does not directly cause ionization

Question 3

ELO 1 Explain Specific Ionization

Answer 3

Ionizing radiation creates ion pairs (+ and - charged).
Specific Ionization is the number of ion-pairs formed per centimeter of travel in a given material.
It is a measure of the intensity of ionization.

Question 4

ELO 2 Describe radioactive interaction of the alpha particle

Answer 4

The alpha particle has 2 neutrons and 2 protons (the same as a helium nucleus), but no electrons, giving it s charge of +2. As the alpha particle passes through material, it strips electrons from the orbits of atoms in its vicinity which requires energy therefore the alpha particle’s energy decreases until eventually it’s expended at which point the alpha particle gains 2 electrons and becomes a helium atom.

Question 5

ELO 2 Describe radioactive interaction of the Beta particle

Answer 5

Beta particles cause ionization by displacing electrons from atomic orbit. Beta-minus ionization occurs from collisions with orbiting electrons. After a few collisions, the Beta particle slows enough to allow it to be captured as an orbiting electron in an atom.

Question 6

ELO 2 Describe radioactive interaction of gamma radiation and list the 3 ways gamma rays energy is reduced.

Answer 6

Because the gamma ray has no mass and no charge, it is difficult to stop and has a high penetrating power.
There are 3 ways by which the energy levels of gamma rays reduce:
- Photoelectron Effect
- Compton scattering
- Pair Production

Question 7

ELO 2 Explain the Photoelectron Effect as it applies to gamma ray interactions

Answer 7

Low-energy gamma ray strikes orbital electron, ejecting it from orbit as a high-energy electron resulting in ionization of the affected atom.
Occurs with gamma rays >1 MeV

Question 8

ELO 2 Explain Compton Scattering as it applies to gamma ray interactions

Answer 8

An elastic collision between an electron and a photon.
The results are ionization of the atom, high energy beta and a reduced energy gamma ray.
Most common with gamma rays 1-2 MeV

Question 9

ELO 2 Explain Pair Production as it applies to gamma ray interactions

Answer 9

High-energy gamma ray passing close to a heavy nucleus disappears and its energy reappears in the form of an electron and a positron.
Original gamma must have at least 1.02 MeV

Question 10

ELO 2 Describe radioactive interactions of neutrons and list the 3 ways neutrons energy levels are reduced

Answer 10

Neutrons have no charge and the same mass as a proton which make them difficult to stop and give them high penetrating power.
The three ways by which neutrons energy levels are reduced:
- Elastic scatter
- Inelastic scatter
- Absorption