The transmission calculation by empirical numerical model and Monte   Carlo simulation in high energy proton radiography of thick objects
  An empirical numerical model that includes nuclear absorption, multiple Coulomb scattering, and energy loss is presented in this work to calculate the transmission of the thick objects in high energy proton radiography, and in this numerical model the angular distributions are treated as Gaussians in the laboratory frame. A Monte Carlo program based on Geant4 toolkit was developed using for the high energy proton radiography experiment simulation, and verifying the empirical numerical model. The two models are used to calculate the transmission fraction of the step-wedge of carbon and lead in proton radiography at 24GeV/c. The two models can reproduce the experiment data, and the differences are analyzed. 
Zheng Na and Xu Hai-bo
physics.ins-det