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Hi, The CORE-CM seminar this week is *November 15*: /William J. Weber (Materials Science and Engineering, University of Tennessee) / "*Effects of Ionization on Damage Formation and Recovery under Ion Irradiation* /*"*/ BPS 1400 at 12:00pm Pizza and cookies available at 11:45am Phil Duxbury _Abstract_ The interaction of ions with solids results in energy loss to both atomic nuclei and electrons. At low energies, nuclear energy loss dominates, and irradiation damage occurs primarily by ballistic collisions. At high energies for fission products and swift heavy ions, electronic energy loss dominates, and the intense ionization can lead to latent track formation or recovery of existing irradiation damage. At intermediate ion energies, including energies of primary knock-on created by fast and fusion neutrons, ballistic and ionization energy losses are of similar magnitude and can lead to synergistic or competitive processes that affect the evolution of irradiation damage. We have integrated experimental and computational approaches to investigate the separate and combined effects of nuclear and electronic energy loss on damage formation and recovery in several materials. Experimentally, we have shown that that there is a synergy between the nuclear and electronic energy loss on damage evolution in amorphous SiO_2 at intermediate ion energies. Large scale molecular dynamics simulations, which include ballistic collisions and local heating based on the inelastic thermal spike model, have been employed to investigate the separate and combined effects of nuclear and electronic energy loss on damage production. These simulations demonstrate conclusively the additive effect of nuclear and electronic energy loss on damage production. On the other hand, ionizationin Ca_2 La_8 (SiO_4 )_6 O_2 from intermediate energy ion irradiation leads to competitive damage recovery processes that decrease damage production. In SiC, irradiation with intermediate energy ions leads to defect formation and amorphization; however, it has been shown that swift heavy ions can induce some recovery of such irradiation damage. Large scale molecular dynamics simulations confirm that swift heavy ions induce defect recovery and recrystallization in SiC that are well described by an inelastic thermal spike phenomenon.