Continuous thoron gas measurement using single scintillation cell – Correction for 212Pb deposition

• Continuous thoron gas measurement using scintillation cell.
• Deposition of 212Pb atoms on the surface of the cell is theoretically estimated.
• Automatic correction for previously deposited 212Pb atoms.
• Method is validated using standard thoron monitors.

Scintillation cells are used in continuous mode for thoron estimation using gross alpha counts. Such methods give rise to overestimation resulting from buildup of background counts due to the deposition of Lead (212Pb). Here, the background counts in the cell for a specific counting period owing to previously deposited 212Pb has been estimated using a model to get a time dependent correction factor. This correction for 212Pb deposition has been utilized to estimate the current thoron concentration of the sample. The concentration obtained by this method is validated using the scintillation cell by grab sampling method and a continuous thoron monitor, RAD7.