Positronium in 1-tridecene

The lifetime and intensity of ortho-positronium in solid phases of 1-tridecene were measured as functions of temperature. At 223 K the transition from the rotator phase to orientational glass was observed. Relaxation from the glassy structure to a rigid crystal was slow and in the time scale of the experiment (several days) could be observed in a limited range of temperatures (190-220) K only. The transition from crystal to rotator occurred at 231 K.