Determination of (241)~Am in weapons grade plutonium for chronometry applications

摘要

Efforts will be reported to develop a method for the determination of (241)~Am in weapons grade plutonium (WGPu) for chronometry applications. The in-growth of (241)~Am from (241)~Pu is a well-regarded nuclear forensic chronometer for duration since last chemical separation [1]. Nuclear forensic sponsors are typically interested in results from two or more independent analytical methods that show statistical agreement, e.g. 95% confidence interval overlap. For ISO 17025 accredited forensics laboratories [2], this overlap must be based upon uncertainties calculated via the Joint Committee for Guides in Metrology (JCGM) methodology outlined in [3] (Taylor series approximation method) and [4] (Monte Carlo method). They are also interested in results with a low relative uncertainty to more tightly constrain the time frame for the last chemical separation. Isotope Dilution Mass Spectrometry (JJDMS) is a well-regarded technique for measurement of (241)~Am [5] for this purpose given its achievable uncertainty, e.g. <1% (k = 2). The focus of this work has been an alternative method using a combination of spectrometry techniques that can approach the same level of precision as IDMS but in an independent manner.