Digital coincidence counting for radionuclide standardization

The 4 pi beta-gamma coincidence method for the absolute determination of nuclear disintegration rates has for decades been successfully applied to a variety of radionuclides, via the use of suites of dedicated analogue electronic modules. The high cost of procurement and maintenance of such systems, as well as the requirement for highly experienced technicians to perform the data collection have prompted the design of more flexible data collection techniques. Recent advances in digital signal acquisition technology have facilitated the possibility of storing pulse information from multiple detector systems along with a time stamp for each recorded event, allowing various radionuclide standardization techniques ( based on the concept of 4 pi beta-gamma coincidence counting) to be implemented ' offline' via the use of dedicated software routines. This brief paper reviews the progress in the development of such ' digital coincidence counting' systems used in the field of radionuclide metrology and may be viewed as a companion article to other papers ( in this issue) on primary methods for radionuclide standardization.