1. The problem statement, all variables and given/known data A natural lithium target 3.8 mg cm-2 thick is bombarded with a 125 µA beam of 3.5 MeV protons initiating a 7Li(p,n) reaction. Assuming a reaction cross section of 300 mb, calculate the activity produced by a 15 minute bombardment. 2. Relevant equations λN=[itex]\phi[/itex][itex]\sigma[/itex]NT(1-e-λt) I=I0e-μx 3. The attempt at a solution 125μA=125μC/s(1 proton/1.602*10-19C)(15*60s)=7.022*1017 protons. I'm not really sure where I would go from here. I got μ/[itex]\rho[/itex]=0.0258 cm2/g. Yet, I can't find the actual linear attenuation coefficent. I figured we would use the activation equation, but I'm not sure on the flux, and the other units.