Distribution of gamma and cosmic ray exposure rates in a 12-storied concrete building

General patterns of the γ and cosmic ray exposure rate distribution inside a 12-storied concrete building were obtained through simultaneous measurements using an intrinsic germanium spectrometer, NaI(Tl) scintillation detectors and a high pressure ionisation chamber. In general, the horizontal γ exposure rate increased with distance from a window, then became constant at the interior of a room. The cosmic ray exposure rate decreased with increasing distance from a window, then became constant within the room. The vertical profile of the cosmic ray exposure rate indicated a marked change between the roof and the upper floors because of the filtering out of the soft electromagnetic component of the cosmic ray flux, then decreased slowly with depth in the building. Gamma exposure rates varied from floor to floor and from room to room because of varying wall compositions. The representativeness of a measured value with regard to these observed patterns is also discussed. (author)