Bismuth germanate and bismuth silicate glasses in cryogenic detectors

Abstract We present and discuss the results of measurements of conductivity and secondary electron emission coefficient of Bi x Ge 1− x O 2−0.5 x (where x =0.13, 0.23, 0.33, 0.47) and Bi x Si 1− x O 2−0.5 x (where x =0.47, 0.57, 0.67) glasses reduced in hydrogen. The surface conductivity of reduced glasses strongly depends on reduction temperature, reduction time and bismuth content. The temperature dependence of the surface conductivity in a high temperature regime is well described by σ ∼exp[−( T 0 / T ) n ] law where n =1/4. The secondary electron emission coefficient of reduced glasses is practically independent of the degree of reduction but increases when binary glasses are modified by alkali ions. The research results confirmed that bismuth silicate and bismuth germanate glasses modified by alkali ions may be good materials for detectors working in cryogenic temperature.