Mohamad-Ziad Charif - Antares

Figure 5.11: Sun’s position taken at the arrival time of each event from data.5.6 Background estimationTo estimate the background (which is due to atmospheric ν and µ events) from thedata in the direction of the Sun, we scramble the data by simulating a fake Sun foreach event. This method has the benefit of eliminating certain uncertainties arisingfrom the use of the Monte Carlo. The scrambling is done by changing the arrivaltime of the each event 3 , leading to a different position in the sky for the Sun at thatgiven time. However this procedure used for choosing a different time is not doneover all of the livetime, that means that each event is randomly given a new timefrom the same period it comes from and not from other periods. For example anevent from the run number 33172 which belongs to the 3pe 9 lines period, will berandomly given a new time from another event belonging to the 3pe 9 lines period.The scrambling as it can be seen in figure 5.12 and 5.13 follows the distribution ofthe Sun’s position as taken from the time arrival of data events quite well (Figure5.11). The good agreement between data, scrambled data, and the µ & ν MonteCarlo can be seen in both the Zenith and Azimuth distribution of the Sun. We canlook at the same distributions of 5.12 and 5.13 again but this time with a qualitycut of χ 2