Comparison of near-background concentrations of Argon-37 and Xenon-133 in the atmosphere.

Radioisotopes of the noble gases xenon and argon can be important indicators of underground nuclear explosions. The Comprehensive Nuclear-Test-Ban Treaty (CTBT) includes monitoring capabilities to identify potential nuclear explosions conducted in violation of the CTBT. This monitoring currently focuses on measurement of the xenon isotopes Xe, Xe, Xe, and Xe.