Improving the sensitivity of radionuclide particulate monitoring stations

A worldwide radionuclide network of 80 stations, part of the International Monitoring System, is being setup to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The radioactivity sampled at these stations is primarily 220Rn progenies. Using the knowledge of the diurnal change of the 220Rn progeny 212Pb the sampled activity at the end of the sampling process can be minimised by choosing the right collection start time. It is shown that improvements of several percents in the minimum detectible concentration (MDC) for CTBT relevant nuclides can be achieved.