Mohamad-Ziad Charif - Antares

Figure 4.5: Percentage of muons simulated/reconstructed as function of the zenithangle θ. θ = 0 ◦ is the nadir, θ = 90 ◦ is the horizontal and θ = 180 ◦ is the zenith.This distribution is before any cuts, and reconstructed using the BBFit reconstructionmethod.Some of these down-going muons are reconstructed inside the detector as upgoing(Figure 4.5 ) due to several factors such as:• The event is actually a down-going multi-µ event but fitted as an up-goingelectron event.• Hits from the optical background.• Choice of the reconstruction strategy but this has a more limited effect.Atmospheric NeutrinosAt the same time the above mentioned muons are created, ν µ are being simultaneouslycreated by the same process, however these neutrinos rarely interact as theygo down from the upper atmosphere, but they do continue through the Earth andinteract exactly just as a neutrino signal would. However, it is important to notethat ANTARES is dominated by atmospheric muons, in figure 3.8 we can see thatthe atmospheric muons’ flux is 6 orders of magnitude higher than the neutrinos’.SimulationThe simulation of these two sources is divided into many steps, and uses differentsoftware packages.We will go through all of them starting with the special steps concerning eachsource.71