Abstract
Positron annihilation in tin has been studied as a function of temperature. The Doppler broadening of the 511keV line has been measured with a germanium photon detector system. For annealed white tin the positron parameters show only a small increase on approach to melting. For the tin sample plastically deformed at 77 K, the grey-white phase transitions are strikingly manifested at 240 and 300 K.