J. Klein, R. Middleton, H. Tang, University of Pennsylvania

Nuclear Instruments and Methods 193 (1982) 601-616

Several modifications have been made to our FN tandem for the quantitative measurement of 10Be. These include the addition of a velocity selector before the high energy analyzing magnet, and a high resolution negative ion injector equipped with an auxiliary Faraday cup which integrates the 10BeO^- current during injection of 10BeO^-. A significant development was the incorporation of an ion chamber in the 10B absorber which facilitates the accurate tuning of the accelerator for 10Be. Factors limiting sensitivity and precision are discussed, and some measured 10Be/9Be ratios are compared with values accurately known from beta-counting. Typical results are presented including those from a sample of oak.