Development of a low-level Ar-37 calibration standard
  Argon-37 is an environmental signature of an underground nuclear explosion. Producing and quantifying low-level Ar-37 standards is an important step in the development of sensitive field measurement instruments. This paper describes progress at Pacific Northwest National Laboratory in developing a process to generate and quantify low-level Ar-37 standards, which can be used to calibrate sensitive field systems at activities consistent with soil background levels. This paper presents a discussion of the measurement analysis, along with assumptions and uncertainty estimates. 
R. M. Williams, C. E. Aalseth, T. W. Bowyer, A. R. Day, E. S. Fuller,   D. A. Haas, J. C. Hayes, E. W. Hoppe, P. H. Humble, ...
physics.ins-det