Investigations on TDCR measurements with the HIDEX 300 SL using a free parameter model.

The Triple to Double Coincidence Ratio (TDCR) method requires a special counting system with three photodetectors. The systems currently used by National Metrology Institutes for activity standardizations are custom built, and up to now the HIDEX 300 SL counter is the only TDCR counter commercially available. At PTB, measurements with a special metrology version of this counter were carried out to investigate its applicability for activity standardizations. The activity results of measurements with the HIDEX counter are compared to those obtained with a PTB-TDCR counter, as such a comparison reduces the model dependence. In addition, a spectrometry method was applied to measure (109)Cd samples and a new TDCR-Čerenkov method was tested with (32)P samples.