Bilateral comparison between PTB and ENEA to check the performance of a commercial TDCR system for activity measurements

• The TDCR counter from Hidex Oy was tested at PTB and ENEA.
• The studies comprised linearity checks and investigation of adjustments.
• A bilateral 89Sr comparison was organized to compare two Hidex counters.

The only commercial TDCR counter from Hidex Oy (Finland), comprising three photomultiplier tubes, was tested at the two National Metrology Institutes (NMIs) PTB and ENEA. To this end, the two NMIs purchased a Hidex 300 SL TDCR counter (METRO version) each and carried out various tests at their laboratories. In addition, the two institutions agreed to organize a bilateral comparison in order to acquire information on the reproducibility of the results obtained with the counters. To achieve this, PTB prepared some 89Sr liquid scintillation samples, which were first measured in various counters at PTB and then shipped to ENEA for comparative measurements.The aim of this paper is to summarize the findings on the counter characteristics and adjustments. In addition, the results of the bilateral comparison between PTB and ENEA are presented and the results from various commercial counters using the CIEMAT/NIST efficiency tracing and the TDCR method are discussed.