Search for an Electrode Dependent Effect in the Dark Conductivity of Anthracene

Abstract

WE have made dark conductivity (DC) measurements in an argon atmosphere on 15 mm diameter scintillator grade single crystals of anthracene. Electrodes and guard rings of aluminium and of gold were plated under vacuum onto the major faces. A steel mask was used to form the guard ring and to hold the crystal in position against a magnetic thermal sink during the plating process. The crystal surfaces were cleaned by allowing them to evaporate for a few minutes at a pressure of 10⁻⁴ mm Hg. The electrode material was evaporated at 10⁻³ mm Hg from a tungsten heat source, the crystals having first been cooled to about 175° K. Care was taken to minimize thermal stressings and to freeze out any water vapour.