where "Z1" and "Z2" are the atomic numbers of projectile and sample atoms, respectively. For "m2/m1" Â«1 and with approximation "m=2Z"; "Z" being the atomic number of "Z1" and "Z2". In equation (3) two essential consequences can be seen, first the sensitivity is roughly the same for all elements and second it has a "Z14" dependence on the projector of the ion. This allows for the use of low energy beam currents in HI-ERDA preventing sample degradation and excessive heating of the specimen.