Evaluation of High-Purity Synthetic Silica Vials in Active and Passive Vial Holders for Liquid Scintillation Counting of Benzene

Abstract

We evaluate high-purity synthetic silica vials in both delrin and active plastic holders (Pico adapters™) for 14C dating, using liquid scintillation counting of benzene. We have designed synthetic silica vials in the form of simple cylinder-cells based on the standard 7-ml vial. We have also designed a delrin holder for supporting 7-ml silica or glass vials. We compare the counting efficiency and background of the silica vials with Teflon, plastic and low-K glass vials for both delrin holders and Pico adapters in the 1220 Quantulus and Packard Tri-Carb 2660 XL, fitted with a plastic detector guard. In the 1220 Quantulus, synthetic silica vials in Pico adapters have the highest figure of merit (FM), closely followed by silica in delrin holders and Teflon. In the Packard Tri-Carb 2660 XL, plastic vials in Pico adapters give the highest FM.