Mohamad-Ziad Charif - Antares

Figure 3.5: Mean kinematic angle between the neutrino and the muon as a functionof energy of the neutrino.kilometers depending on its energy (Figure 3.6 ), so the photons generated by theradiation would be distributed over a large volume. The detector thus has to belarge enough in order to track a fair portion of the emissions as it passes throughthe detector. Since the ν-matter cross section is very small, we would need theinteracting medium to have primarily two proprieties, to be dense and extremelylarge, the solution is to use the Earth itself as the interacting medium. This isachieved by looking at upward going neutrinos passing through from the otherside of the Earth and interacting below the detector. The reason for this has todo with the detection principle: we want to detect neutrinos induced muons, butthe fact is that since the Earth is bombarded constantly and heavily by cosmicrays, and its interaction with our atmosphere produce many particles (Figure 3.7)including muons. And as we saw earlier muons can travel large distance andcertainly the distance between the atmosphere to the surface of the Earth if theyare energetic enough. So the detection will be contaminated by muons (Figure3.8) coming from above the detector as a result from cosmic rays interactions, soby selecting muons that are traveling upward in the detector apparatus, we caneliminate this contamination 1 .3.2.1 ANTARESANTARES[67] (Astronomy with a Neutrino Telescope and Abyss environmentalRESearch) is a neutrino Cherenkov telescope located 40 km off the city of Toulon,1 Of course cosmic rays create neutrinos as well, and they can travel through the Earth, but thiswill be discussed later.39