Preparation of new 10Be and 26Al AMS standard reference materials

Accelerator Mass Spectrometry (AMS) measurements require reliable standards for calibration. Beryllium-10, Al-26, Cl-36, and Ca-41 AMS standards that were prepared by the author are used as primary normalization standards in most AMS laboratories worldwide. The expansion of applications and AMS facilities, accordingly an increase in sample measurements, over the last three decades has largely depleted the available stock of Be-10 and Al-26 standards that were prepared in 2001 as a series known as the "2001 or 01 dilution". We have undertaken the task of making a new series of Be-10 and Al-26 AMS Standard Reference Materials (SRM) ("2014 or 14" series) that were prepared from the same parent solution used to produce the 2001 standards. Seven different concentrations of Be-10 AMS standards were prepared from a stock solution 2001-4 by sequential dilution with (similar to 10 kg of) 36.5 mg Be/g carrier solution. The Be-10/Be ratios of the new standards are 1.01 x 10(-13), 5.02 x 10(-13), 2.507 x 10(-12), 2.508 x 10(-12), 7.523 x 10(-12), 1.504 x 10(-11), and 2.502 x 10(-11). Six different concentrations of Al-26 AMS standards were prepared from a stock solution 2001-3 by sequential dilution with a 35.7 mg Al/g carrier solution. The Al-26/Al ratios of the new standards are 1.51 x 10(-13), 5.01 x 10(-13), 2.501 x 10(-12), 7.501 x 10(-12), 1.500 x 10(-11) and 5.000 x 10(-11). Both Be-10/Be and Al-26/Al ratios of the new 2014 SRM were measured by five AMS laboratories; excellent linearity as well as agreement with the 2001 standard were observed. New 2014 Be-10 and Al-26 SRM are available for the AMS community and are being distributed in the same way as the Cl-36 and Ca-41 SRM.