Radiation Flashcards
What are atoms made up of
Protons
Neutrons
Electrons
What is the nucleus made up o?
Neutrons
Protons
(Mostly empty space)
Protons are….
Positively charged
Neutrons are
Neutral
Electrons are
Negatively charged
What are the reasons for unstable atoms?
Too much mass
Too much charge
Too much energy
What is radiation
An unstable nucleus stabilising itself by emitting some energy, mass or charge.
What are the three main types of radiation
Alpha
Beta
Gamma
Alpha
2 protons and 2 neutrons
Heavy
Easily absorbed
Tiny range in air
How can we Bloch alpha radiation
Sheet of paper
Beta
Fast moving electron ejected from the nucleus
Neutron decays to a proton and electron
Then the electron is ejected
Longer range than alpha
How can we block beta
Few mm of aluminium
Gamma
Electromagnetic wave
No mass
No charge
Infinite range in air
How can we block gamma rays
Few cm of lead
Few metres of concrete
ION
Charged particle
Ionisation
Process of turning a neutral particle (atom) into a charged particle
By removing an electron
What radiation causes the most ionisations per millimetre
Alpha has the greatest ionisation density
What is activity (A)
Number of nuclei decaying per second
What is the unit of activity
Becquerel (Bq)
What is absorbed does
Measure of the radiation energy absorbed per kg of tissue
Unit of absorbed dose (D)
Gray (Gy)
Huge unit
Radiation weighting factor (Wr)
Number representing how dangerous the radiation is
What is the unit of equivalent dose
Sieverts (Sv)
Equivalent dose rate
Length of time in which an equivalent does is received
Shorter the time = greater the harm
Unit for equivalent dose rate
Siverts per second (Svs-1)
Half life
Time taken for the activity to half
What is an atom
Smallest fragment of matter that retains the qualities of the element
What is an element
Only one type of atom
Molecule
Combined atoms
Compound
Substance containing two or more types of atom
Radioactive count rate
Measure of the background radiation in a certain time
What is nuclear fission
Occurs when a neutron is fired at a heavy nucleus
Nucleus breaks into 2 smaller nuclei and releases neutrons + energy
3 sub-atomic particles
Proton (1+)
Neutron (no charge)
Electron (1-)
Nuclear fusion
Two smaller nuclei are fused together
This produces 1 large nucleus + neutrons + energy
Absorbed dose symbol and unit
Grays (Gy)
D
Main causes of background radiation
rocks and soil that contain radioactive material
The human body
Cosmic rays
Symbol for activity and its unit
A
Bq
Applications of nuclear radiation
Tracers- locate cracks in water pipes gamma cements in medicine
Sterilisation- hospital equipment and food
Treatment- cancer (cobalt - 60)
Element
Only one type of atom
Molecules
Combined atoms
Compound
Two or more types of atoms
