P8 Radiation Flashcards
3 types of nuclear radiation
gamma
alpha
beta
what is gamma radiation
electromagnetic radiation from the nucleus
which type of nuclear radiation is the most ionising
alpha
what is the range (in air) of alpha radiation
a few centimetres
what is the range (in air) of beta radiation
1m
what is the range (in air) of gamma radiation
virtually unlimited
what can stop alpha radiation
a few sheets of paper
what can stop beta radiation
a few millimetres of aluminium
what can stop gamma radiation
several centimetres of thick lead OR meters of concrete
what is radioactive activity
rate at which a source of unstable nuclei decays
what unit is used to measure activity of a radioactive source
becquerel (Bq)
what is ‘count-rate’
number of decays recorded each second
what device records the number of decays per second
Geiger Muller tube
Where does background radiation come from
rocks
cosmic rays
fallout from nuclear weapons
why are gamma emitting sources used for medical tracers and imaging
gamma rays do not cause too much damage to cells
not ionising
what is nuclear fusion
when two small, light nuclei join together to make one heavy nucleus
what is nuclear fission
splitting of a large unstable nucleus in to two smaller nuclei
how does nuclear fission occur
an unstable nucleus absorbs a neutron,
it splits into smaller nuclei,
and emits 2 or three neutrons, plus gamma rays
how can you prevent radioactive contamination?
shielding, removing or moving away from the source of radiation
how are gamma emmiting tracers used in medecine?
injected or swallowed by patient
gamma cameras create an image of where the tracer has gone
what is irradiation
exposing an object to nuclear radiation
what is the ‘half life’ of a radioactive source
time taken for half the unstable nuclei to decay
What is ionising radiation?
Can damage or kill cells
what is activity of a radioactive substance
overall rate if decay of all the isotopes in a sample
what is activity of a radioactive substance
overall rate if decay of all the isotopes in a sample
what is activity measured in
Becquerel
what is one becquerel equal to
1 decay per second