Alternative treaty monitoring approaches using ultra-low background measurement technology

The International Monitoring System (IMS) of the Comprehensive Test Ban Treaty includes a network of stations and laboratories for collection and analysis of radioactive aerosols. Alternative approaches to IMS operations are considered as a method of enhancing treaty verification. Ultra-low background (ULB) detection promises the possibility of improvements to IMS minimum detectable activities (MDAs) well below the current approach, requiring MDA⩽30 μBq/m3 of air for 140Ba, or about 106 fissions per daily sample.