radiation Flashcards
types
alpha
beta
gamma
what is an alpha particle?
a helium nucleus-two neutrons and two protons
alpha-ionising and penetrating
alpha is highly ionising due to it’s size
not very penetrating-a few cm in air, absorbed by a sheet of paper
how do smoke detectors work?
-alpha radiation ionises air particle
-causes a current to flow
-if there is smoke in the air, it binds to the ions
-so current stops and alarm sounds
beta particle
a high-speed electron
beta-ionising and penetrating
moderately ionising
moderately penetrating-a few metres in air, absorbed by a sheet of aluminium
what happens for every beta particle emitted?
a neutron in the nucleus turns into a proton
why are beta emitters used to test the thickness of sheets of metal?
-particles aren’t immediately absorbed
-don’t penetrate as far
-variations in thickness affect amount of radiation passing through the sheet
activity
the rate at which a source of unstable nuclei decays
what is activity measured in?
becquerel (Bq)
count-rate
the number of decays recorded each second by a detector
what measures count-rate
geiger-muller tube
gamma rays
waves of EM radiation released by the nucleus
gamma-ionising and penetrating
weakly ionising as they tend to pass through rather than collide with atoms, highly penetrating, travel a long distance in air, absorbed by thick sheets of lead/concrete
what else can atoms release when they decay?
neutrons
