Ionising radiation
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What is ionizing radiation
• radiation with enough energy to remove tightly bound electrons from the orbit of an atom • causing the atom to become charged
Nature of alpha
• positively charged • made of 2 protons + 2 neutrons • heavy • slow
What is alpha stopped by
• clothing • dead skin
Health risks of alpha
• ingested - particles absorb in a small mass of tissue • creates increased damage and increase risk of radical interactions
Nature of beta
• negatively charged • fast • light
What is beta stopped by
• thin layer of substance • e.g aluminum
Health risk of beta
• sources near body still pose a risk
Nature of gamma
• made up of packets called photons • light • no charge
What is gamma stopped by
Dense materials e.g. lead
Health risks of gamma
Lower danger
Nature of neutrons
No electric charge Heavier than protons
What are neutrons stopped by
Thick materials that are rich in hydrogen e.g. water
Health risks of neutrons
Very dangerous High risk after they’ve been absorbed
Definition of half-life
Time taken for the radioactivity of a specified isotope to fall to half its original value
Which pollutant property does half-life determined
Persistence
Why do you think everybody’s risk from each source is not equal
People may live in different geographical areas, so other areas might have less Different age groups have different medical conditions
Definition of contamination
Physically carrying radioactive materials, which when they release radiation, may cause exposure
Definition of exposure
Absorption of ionising radiation
What is the difference between exposure and contamination
Exposure is about the radiation dose received, while contamination is about the presence of radioactive material
Who are most at risk from radiation exposure
Children Pregnant women Plants People living in granite areas
Most common uses of radioactive materials and ionising radiation
Research e.g tracers Medical appliances e.g x-rays Nuclear power generation
Close sources
Prevent workers from coming into direct contact with the source, by enclosing the source in a container
Absorbers
Materials should be used as barriers to prevent radiation reaching workers. Thickness etc will depend upon type of radiation involved and space available
Distance from the source and the inverse square law
Inverse square law - distance from the source increases = drop in exposure 1/distance^2