The Transient Temperature Dependence of Radioactive Reference Lights

Scintillating phosphors intimately mixed with long lived radionuclides are used to construct stable reference lights for many measurement applications. If phosphors having long lived traps are used in the construction of such lights the temperature dependence of light emission may be a complicated function of the temperature history of the reference light. The transient temperature dependence has been calculated for several traps ranging in depth from 0.5 to 1.5 ev. Experimental data are presented for Harshaw TLD-100, CaF2: Mn, CaF2: Dy, ZnS, and NaI(Tl). The calculations and measurements show that phosphors should be chosen which have either very deep traps not likely to produce light at normal operating temperatures or those which have shallow traps likely to equilibrate in a short time.