Die dickenabhängige Drehung der Lichtausbeutecharakteristik von Anthrazen- und p-Terphenylkristallen beim Beschuß mit α-Teilchen

Abstract

Thick single crystals of anthracene and para-terphenyl have a maximum of their scintillation yield with the impact direction of the α-particle perpendicular to a cleavage plane. For thin crystals the direction of maximum light output shows a deviationγ up to 20° depending exponentially on the crystal thickness.

Blackening the backside of the crystals decreasesγ. The existence of far-reaching excitons in theb,c-plane gives a rough picture of these phenomenas.

A minimum of the scintillation yield of para-terphenyl crystals is measured at a temperature of −90°C. Below −90°C the scintillation light shows a new decay component with a period of 2 μsec.