Measurement of trace 129I concentrations in CsI powder and organic liquid scintillator with accelerator mass spectrometry

Levels of trace radiopurity in active detector materials is a subject of major concern in low-background experiments. Procedures were devised to measure trace concentrations of 129I in the inorganic salt CsI as well as in organic liquid scintillator with Accelerator Mass Spectrometry (AMS). Improvements in sensitivities by several orders of magnitude over other methods were achieved. No evidence of 129I contaminations in CsI and liquid scintillator were observed, from which limits of <1.5 × 10−13 g/g and <2.6 × 10−17 g/g, respectively, were derived. These are the first results in a research program whose goals are to develop techniques to measure trace radioactivity in detector materials by AMS.