Detection of krypton in xenon for dark matter applications

Understand

We extend our technique for observing very small concentrations of impurities in xenon gas to the problem of krypton detection.

• We use a conventional mass spectrometer to identify the krypton content of the xenon, but we improve the sensitivity of the device by about five orders of magnitude with a liquid nitrogen cold trap.
• We find that the absolute krypton concentration of the xenon can be inferred from the mass spectrometry measurements, and we identify krypton signals at concentrations as low as 0.5x10^{-12} mol/mol (Kr/Xe).
• This technique simplifies the monitoring of krypton backgrounds for WIMP dark matter searches in liquid xenon.