Medidas de intensidade de múons cósmicos com cintiladores plásticos

Abstract

The study of cosmic radiation is of utmost importance to astrophysics. Particles from different locations, from inside the solar system, and outside it, constantly arrive on Earth, carrying a lot of information about its origin. When these particles arrives to Earth's atmosphere they initiate a cascade of secondary particles resulting from the interaction of the primary cosmic ray with the atmosphere. From this rain of secondary particles, muons are the most abundant charged particles that reach the Earth's surface. Muons are highly penetrating, which can be a very big problem in some experiments, even if underground, of other particles. Because of their large number, they become extremely necessary in reconstructions of air showers to obtain information about the primary particle. Having knowledge of its characteristics, such as flux and distribution, noise in some experiments can be treated and other studies can be optimized. Muon intensity in the Earth's surface is well known to be anisotropic and has dependence on the zenith angle of I(◊)=I 0 cos n (◊). For simplicity in the calculations, this n exponent is often used with a value of 2, but studies show that this parameter has dependence on the geographical position and on the energy range of muons in question. This dissertation proposes a simple method for accurate determination of the exponent n and muon vertical intensity simultaneously, that can be determined quickly in any laboratory cosmic rays using a particle detector, which was called Muon Telescope. As a result of the application of the method on the Leptons Laboratory, in Campinas -SP -Brazil, the value for n that was obtained is about 2.30 and a value for the vertical intensity of muons around 146.40Hz/m 2 sr. This data is very satisfactory and according to similar experiments previously conducted at the Laboratory. This method was applied on Fermilab, located at the United States. On this new geographical location, the results were different from that obtained at Campinas, with n about 3.66 and the vertical intensity around 158.33 Hzm ≠2 sr ≠1 . The same experiment with the telescope will be held in other geographical locations in order to check the n exponent behavior and the muon intensity at different locations.