Background Monte Carlo

Background MC files were obtained from the Zeuthen and Sweden mass production of atmospheric muon backgrounds (versions 1 to 3 from Sweden and version 1 to 4 from Zeuthen). Information on the mass production from Sweden is available at http://www.physto.se/$\sim$edsjo/amanda/mc/status.html and for the mass production from Zeuthen at http://www.ifh.de/$\sim$biron/mc/mc_status.html. The Swedish filter was applied to AMASIM files obtained from Zeuthen and were reconstructed using the standard hit cleaning and run selections in appendix A. The files obtained from Stockholm had already been filtered (Swedish filter) and reconstructed with the standard hit cleaning and run selections. The energy reconstruction were applied to these events. A total of $\sim$5 live days of background Monte Carlo was presented by John Kim at the Uppsala collaboration meeting and shown at the ICRC. These plots and tables are shown in Appendix C

Unfortunately, the simulated background MC did not agree with experimental data to the level of accuracy that we would like. Therefore, there is an effort to make improvements to AMASIM. They include distinct pulse shapes for the twisted quad electrical cables (strings 5 to 10) and a correction to the calibration procedure that determines the pulse amplitudes and number of photo-electrons (Npe) from the uncalibrated pulse amplitudes generated by AMASIM. John Kim had previously corrected AMASIM to produce the equivalent of delayed output from the SWAMP (same as the Experimental Data), instead of the prompt SWAMP output. The delayed pulse shape is significantly wider than the prompt pulse shape, so the alphas used for time calibration will be different. The calibrate file, which converts the pulse amplitudes from AMASIM to Npe used alphas for the prompt ADC output and not the delayed ADC output. John Kim calculated the alphas for delay ADC output by making linear fits to the leading edge times vs. sqrt(1/ADC) distribution for each module from the Monte Carlo (A calibrate run was simulated with the new version of AMASIM). These new alphas have been included in the calibration file and are used in processing the Monte Carlo data. At this stage , the statistics is low for the background Monte Carlo using the improved version of AMASIM. The processing chain for the Monte Carlo (Both background and Signal) is (BASIEV (background) or NUSIM (signal)) $\Rightarrow$ MUDEDX $\Rightarrow$ AMASIM (new version as mentioned above) $\Rightarrow$ LBNL filter $\Rightarrow$ UCI filter $\Rightarrow$ Energy Reconstruction. Existing mudedx files from Zeuthen and Stockholm are piped into AMASIM (new version) and the rest of the processing chain. This has only been done for version 1 of the background files from Zeuthen. As confidence is gained in the new procedures, additional files will be re-processed to increase the size of the background sample.