Charge deposition in the SCT due to beamloss

The purpose of this study was to estimate the distribution of charge collected by the strips 6 of ATLAS SCT modules in a 25ns window under two LHC proton beam scrape scenarios. 7 This was done in order to see whether this charge would be greater than the nominal amount 8 above which damage to the modules is expected to occur, which is 5nC/strip over 25ns. 9 Specifically, the damage is expected to occur to the channels of the front-end ABCD3T 10 binary readout chips of the SCT modules. Due to limited numbers of fully simulated single 11 proton collisions with the beam pipe (at 450 GeV) and the TAS collimator (at 7 TeV) a 12 method of sampling SCT hits-with-replacement is developed to obtain an upper limit on the 13 charge per strip for a 108 proton scrape over 25ns. Under this assumption the maximum 14 charge collected per strip is determined to be less than 0.4nC for the 450 GeV beam pipe 15 scrape scenario and less than 1.9nC for the 7 TeV TAS collimator scrape scenario, within 16 the damage threshold in both cases.