Absolute standardization of 241Pu by the TDCR technique and effect of the beta spectral shape

The NMISA participated in the 2010 international key comparison of 241Pu, standardizing the inter-comparison solution by the TDCR efficiency calculation technique. Special attention was paid to ensure accurate efficiency calculation for this low-energy, pure beta-emitter: in particular the effect of low-energy stopping powers on the calculation of ionization quenching was assessed and an optimal value for the quench parameter, kB, was determined. In addition, phototube efficiency mismatch was accounted for by a software minimization technique. The effect of the beta spectral shape on the activity extracted from data analysis was assessed and found to be significant. Based on the results of this work we propose a new value for the average beta-particle energy.

► Absolute standardization of 241Pu by the TDCR efficiency calculation technique. ► Assessment of the effect of the beta spectral shape on the activity determination. ► Refinement of the LSC efficiency calculation.