Speaker
Description
Authors: 1. M.L. Smith, 2. W.M. van Wyngaardt, 3. A.H.H. Bowan, 4. C.M.B. Keevers, 5. M. Zarifi and 6. E.L. Clark (all from ANSTO)
Radionuclides have been standardized by 4π(PC)-γ coincidence counting at ANSTO using an atmospheric pressure proportional counter (PC) with conventional analogue electronics since the 1970s. The ANSTO Radionuclide Metrology (RM) group extended this capability by purchasing a High-Pressure Proportional Counting (HPPC) system from the National Physical Laboratory (NPL, UK). This system, which is operated with a NaI(Tl) well detector, has benefits of energy discrimination in the beta channel and can also be applied for 4π-γ counting and 4πβ-γ sum counting.
The instrument consists of a 2 inch diameter HPPC that can be inserted into a 5 inch well-type NaI(Tl) detector. The proportional counter is used with P-10 or methane counting gas and is capable of pressures up to 10 atmospheres at low gas flow rates. The HPPC, pressure control system, shielding and table were manufactured by NPL as a duplicate of their system and will provide a unique opportunity for collaboration between the laboratories.
Two data acquisition systems are being used with the HPPC. The first is a well-established computer based Digital Coincidence Counting (DCC) system that was originally developed in collaboration with the NPL, and is still utilised by both laboratories. The second employs an off-the-shelf CAEN-6720B Pulse-shape discriminator in combination with coincidence data analysis scripts that have been developed using C++ and Python as an update or alternative to DCC software.
In this work, we will show the validation of the HPPC system against our existing atmospheric proportional counter using Co-60, Tc-99m, and I-123. The newer data acquisition system and software will be compared in view of the eventual replacement of the aging DCC system hardware.
