The effect of layer number and substrate on the stability of graphene   under MeV proton beam irradiation
  The use of graphene electronics in space will depend on the radiation hardness of graphene. The damage threshold of graphene samples, subjected to 2 MeV proton irradiation, was found to increase with layer number and also when the graphene layer was supported by a substrate. The thermal properties of graphene as a function of the number of layers or as influenced by the substrate argue against a thermal model for the production of damage by the ion beam. We propose a model of intense electronically-stimulated surface desorption of the atoms as the most likely process for this damage mechanism. 
S. Mathew, T.K. Chan, D. Zhan, K. Gopinadhan, A.R. Barman, M.B.H.   Breese, S. Dhar, Z.X. Shen, T. Venkatesan and John TL Thong
cond-mat.mes-hall