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2014 ANNUAL REPORT 131 Distributed Partnership at a Glance ATR NSUF and Partners Facilities and Capabilities University of Wisconsin - Madison Tandem Accelerator Ion Beam Collaborators University of Wisconsin Madison K. Linga Murty principal investigator Jacob Eapen co-principal investigator Ram Krishna co-principal investigator Figure 6. Temperature and beam-current profiles during irradiation at 300 K 1 dpa and 2.0 MeV C . Accomplishments Ion-irradiation experiments were conducted on the HOPG and NBG-18 samples at displacements per atom dpas of 1 to 25 and tempera- tures ranging from 300 to 900 K. Damage was initiated with C ions at 2-MeV energy.The fluences at 25 dpa and 1 dpa are 2.21017 ions cm2 and 8.81015 respectively.The test durations for the 25-dpa and 1-dpa samples were 4.5 hours and 12 minutes respectively.The average displacement energy was 28 eV.Table 1 shows details of the irradiations at different temperatures and dpas. Figure 1 shows the 2-MeV carbon- implantation and damage profiles calculated using Stopping and Range of Ions in Matter SRIM 2012.03 software and assuming a displace- ment-threshold energy of 28 eV and a mass density of 2.253 gcm3 . As indicated in the plot 25 dpa peak corresponds to a fluence of 2.21017 Ccm2 13 at. of carbon in the peak.Temperature and beam-current profiles are shown in Figures 2 through 6.Tables 2 and 3 show the ratio of the peaks for each sample. Publications and Presentations 1. J. Eapen R. KrishnaT. D. Burchell K. and L. Murty 2014 Early Damage Mechanisms in Nuclear Grade Graphite Under Irradia- tion Materials Research Letters Vol. 2 pp. 4350.