Exponential Attenuation and Beta Particle Range (solved) 1. The problem statement, all variables and given/known data I am given a beta emitter and its atomic mass, as well as the atomic mass of its daughter, which have a difference of 0.0034 amu. I am to determine the range of the particles in air. 2. Relevant equations I am given the law of exponential attenuation: I=I0e^(-ux) And substituted for mass attenuation coefficient: I=I0e^(-um*px) um and p(rho) are readily available, and can be considered given 3. The attempt at a solution So I am looking for x, but I do not know I0 (is there some relation between mass or energy and intensity?), and if I'm looking for the range, I assume I to be 0 (if intensity is energy flux x velocity, at the end of the range it must approach 0) which opens up all sorts of nasty when we try to find ln0 (which, essentially approaches infinity).