IB PHYSICS Topic : Atomic and Nuclear Physics – Properties of Alpha, Beta and Gamma Radiation

Alpha, beta and gamma radiation are produced when a nucleus decays. Their properties are summarised in the following table.

Propert	Alpha	Beta	Gamma
Nature	Helium Nucleus, two protons and two neutrons	Fast moving electron,	Energetic photon
Effect on photographic film	Yes	Yes	Yes
Approximate number of ion – pairs produced in air per mm			1
Typical material needed to stop it	0.01 mm thickness of aluminium Piece of paper Few cm air	A few mm aluminium	10 cm lead
Penetration ability	Low	Medium	High
Typical path length in air	A few cm	Less than 1 m	Infinity
Deflection by magnetic or electric fields	Deflected since positively charged	Deflected since negatively charged	No deflection
Speed	About	Aboutbut very variable
Typical energy, eV	About 5 MeV	A few KeV to a few MeV	A few keV
Mass, kg			0