p8: radiation Flashcards
(17 cards)
what are 3 types of nuclear radiation
alpha
beta
gamma
what is gamma y radiation
electromagnetic radiation from the nucleus
what type of nuclear radiation is the most ionizing
alpha
what is the range in air of alpha, beta, and gamma radiation
alpha: a few cm
beta: 1m
gamma: unlimited
which materials can stop alpha, beta, and gamma radiation
alpha: sheet of paper
beta: thin aluminum sheet
gamma: thick lead / concrete
which type of nuclear radiation does not cause a change in the structure of the nucleus when it is emitted
gamma
what is radioactive activity
the rate at which a source of unstable nuclei decays
what unit is used to measure the activity of a radioactive source
becquerel (Bq)
what is ‘count-rate’
number of decays recorded each second
what is meant by the half-lie of a radioactive source
time taken for half the unstable nuclei to decay
what is irradiation
exposing an object to nuclear radiation
what is radioactive contamination
unwanted presence of substances containing radioactive atoms on or in other materials
where does background radiation come from
rocks
cosmic rays
fallout from nuclear weapon testing
nuclear accidents
why are gamma-emitting sources used for medical tracers and imaging
gamma rays pass through the body without causing much damage to cells
hat is nuclear fission
when 2 light nuclei join to make a heavier one
what is nuclear fission
the splitting of a large and unstable nucleus into two smaller nuclei
how does nuclear fission occur
an unstable nucleus absorbs a neutron, it splits into 2 smaller nuclei, and emits 2 or 3 neutrons plus gamma rays
