Detecção de múons atmosféricos a 556 m.s.n.m. usando um detector Cherenkov de água (Caju).

Abstract

The Caju Cherenkov detector, located at the Academic Physics Unit (UAF, from the portuguese Unidade Acadêmica de Física) of the Federal University of Campina Grande (UFCG, from the portuguese Universidade Federal de Campina Grande), it is part of a set of water Cherenkov detectors (WCD) of the LAGO collaboration (Latin American Giant Observatory), this being a non-centralized collaborative network composed of 10 Latin American countries and Spain, which has as main objective the research in three areas of Particle Astrophysics: extreme universe, space weather phenomena and atmospheric radiation at the ground level. Such detectors measure the passage of charged ultra-relativistic particles on the Earth’s surface through the emission of Cherenkov radiation, particles produced from collisions of primary Cosmic Rays (CR) with atmospheric nuclei, thus forming the so-called extensive air showers. Functional since February 2018, the Caju detector’s main objective is the study of solar events and how they affect the flow of particles that reach Earth. It consists of a water tank with an effective volume of approximately 3.88m3 and a Hamamatsu R5912 photomultiplier coupled to a digitizer plate, making signal measurements almost continuously, signals coming from the passage of electrons / positrons, muons generated during the evolution of the cascade and also electrons / positrons generated from the decay of muons inside the tank. With this data, it is possible to calculate the flow of secondary particles at ground level (about 556 m altitude, for Campina Grande-PB). In this work, we present the complete physical structure of the tank and its components, the water purification procedure and the calibration of the detector through the identification of the Stable Working Region and the characterization by VEM. The muon average lifetime curve was also characterized and, finally, we present the initial results originated from the processing of data collected in the second quarter of 2019 along with corrections carried out through the local atmospheric pressure.