Besides energy deposition（ED）

mass deposition（MD） and charge exchange（CE）were also considered as important facors in the survival of organism undet low energy ion beam irradiation If was proposed that the MD and the CE have indirect effect of protecting DNA from damage

and then an equation of the EMC model describing the survival of organiam irradiated by low energy ion besm was deduced and some typical curves were given

With this equation

some expetimemtal data about survival were well fitted In addition

the presumption that the MD product could damage DNA was questioned by the EMC model

thus further supporting the theortical basis of the EMC model