Commercial of the shelf (COTS) SRAMS were investigated by measurements and simulation in terms of radiation hardness. For the simulations the GEANT4 tool was used. With GEANT4 it is possible to determine the different particles generated by the applied energy as well as the radiation source. It was found that the single event upsets (SEU) is related to the radiation energy, technology node and react differently for the investigated SRAM. Furthermore a possible correlation between the generated particles and the SEU was found.