Preparation of a 219Rn trap to measure the half-life of 211Pb

• Radon-219 emanated from 223Ra sources was trapped in a liquid scintillator.
• The liquid scintillator sources contained 211Pb.
• The 211Pb half-life was measured using a TDCR counter.

A Petri dish was filled with liquid scintillator and then used to trap 219Rn from a 223Ra source. The liquid scintillator was then transferred to a vial which was measured in a custom-built triple-to-double coincidence ratio (TDCR) counter. Two Cherenkov samples were prepared in a similar manner. The measurements were used to determine the 211Pb half-life which was found to be 36.165(37) min.