Measurement of 237Np in environmental water samples by accelerator mass spectrometry

Abstract

Accelerator mass spectrometry (AMS) was used to measure ²³⁷Np in environmental water samples extracted from Irish Sea sediments. The samples were of limited volume (∼700 ml) and of low activity (0.06–0.79 mBq l⁻¹; 2.30–30.3 pg l ⁻¹). AMS proved to have the required sensitivity for measuring these samples, and was in principle capable of measuring much smaller amounts, as low as 0.4 μBq (3.9 × 10⁷ atoms). However, the background level in the procedural blanks showed that there was a systematic low level ²³⁷Np contamination of each sample, arising from the ²³⁹Np yield monitor used in the separations procedure, which effectively increased the detection limit of these analyses.