A new approach to measure Rn exhalation rate out of building walls

The novel technique has been developed to measure Rn exhalation out of structural material surfaces. The majority of Rn daughter nuclides are in the form of positive ions right after their alpha decay process. By applying an appropriate electric field between a wall and a Si detector, the positive ions are accumulated directly on the radiation-sensitive electrode of the Si detector, and real-time alpha spectrometry is performed. This new method can be utilized for existing structures without using destructive means. The basic characteristics of the system and experimental results for several building structures are presented