Section 7 - Radioactivity and Particles Flashcards
1
Q
What emits radiation?
A
Nuclei of unstable isotopes
2
Q
Background radiation sources
A
- Space
- Living things
- Mountains
3
Q
Ionisation
A
- Caused by radiation colliding with atoms and knocking off electrons
- Turns atoms with no overall charge into ions
- The further the radiation can penetrate before hitting an atom the less ionising it is
4
Q
Alpha particles
A
- 4/2 Helium nuclei
- Short penetration distance, doesn’t travel far in air
- Deflected by electric and magnetic fields due to charge
- Strongly ionising
5
Q
Beta particles
A
- Electron emitted from nucleus on an atom when neutron turns into a proton and electron
- Moderately ionising and penetrating
- Deflected by electric and magnetic fields due to charge
6
Q
Gamma rays
A
- No mass or charge
- Weakly ionising
- Only emitted after alpha/beta decay
- Loss of excess energy from nucleus
7
Q
Medical tracers
A
- Use gamma or beta radiation
- Detector tracks distribution around body
8
Q
Industrial tracers
A
- Use gamma radiation
- High gamma radiation will be detected at cracks in pipes
9
Q
Nuclear fission definition
A
The splitting of an atom
10
Q
Nuclear fission process
A
- Slow moving neutron fired towards uranium-235
- Neutron absorbed by atom, causing atom to become unstable and split
- This sends of 3 more neutrons, and forms 2 daughter nuclei
- Energy given out in kinetic energy of particles (thermal)
- (Gas-cooled) Gas passed through heat exchanger where it gives energy to water, water then turns to steam
11
Q
Moderator
A
- Usually graphite or water
- Slows down neutrons to ensure successful collision
- Sustains chain reaction
12
Q
Control rods
A
- Often boron
- Limit rate of fission by absorbing excess neutrons
