where an average energy, dE, is lost locally to the medium per unit density and per path
length traversed, dl. The mass collisional stopping power depends on the energy and
charge of the decelerating particle, and the atomic number of the stopping medium and is
nearly density independent. In reality, charged particles lose a variable burst of energy for
each interaction, but this statistical energy straggling is often ignored and “continuous
slowing down approximation (CSDA)” is assumed. This allows for the determination of a
unique “CSDA range” of the charged particle: