Reducing DRIFT Backgrounds with a Submicron Aluminized-Mylar Cathode

Understand

Background events in the DRIFT-IId dark matter detector, mimicking potential WIMP signals, are predominantly caused by alpha decays on the central cathode in which the alpha particle is completely or partially absorbed by the cathode material.

• We installed a 0.9 micron thick aluminized-mylar cathode as a way to reduce the probability of producing these backgrounds.
• We study three generations of cathode (wire, thin-film, and radiologically clean thin-film) with a focus on the ratio of background events to alpha decays.
• Two independent methods of measuring the absolute alpha decay rate are used to ensure an accurate result, and agree to within $10\%$.