Beryllium-10: Half-life and AMS-standards

Absolute AMS measurements of /sup 10/Be require reliable standards for calibration. Among the existing standards, rather large differences have been observed. These differences were found partially to be due to the different half-life values which were assumed. Also for comparison of AMS data with activity measurements, it is necessary to know the /sup 10/Be half-life as precisely as possible. Starting with 5 ml of the standardized ORNL-MASTER solution, a working solution with a well-defined /sup 10/Be content was prepared. Its specific activity was determined by liquid scintillation counting. This measurement yielded a new value of (1.52 +- 0.05) My for the /sup 10/Be half-life, which is in agreement with the previously reported values but is about three times more accurate. Two independent dilution series produced new AMS standards with /sup 10/Be//sup 9/Be ratios of the order of 10/sup -10/ and 10/sup -11/. These standards were measured at the ETH/SIN AMS facility with high accuracy and are compared with other available /sup 10/Be standards. 15 refs, 2 figs., 3 tabs.