Transmission and line broadening of resonance radiation incident on a resonance absorber

Abstract The transmission of resonance radiation emitted from a source of finite thickness and passing through an external resonance absorber is discussed. The transmission integral is examined for both a linear and a Gaussian distribution of radioactive atoms in the source. Several special cases are presented, and the general case is evaluated by numerical integration. Over the range of values considered, the transmitted line shape closely approximates a Breit-Wigner curve whose width is greater than the natural width of the transition. This line broadening, caused by resonance absorption in the source and in the external absorber, is presented graphically as a function of source and absorber thickness.