Prestaciones del detector AMS-02 para el estudio del canal de positrones de los rayos cósmicos

Abstract

Since AMS-02 underwent two test-beams at the CERN facilities in 2010, a lot of work has been put into the AMS software to have an event reconstruction with calibrated subsystems and a realistic Monte Carlo simulation. The bulk of the work presented in this document takes place at the first test-beam epoch and it constitutes the groundwork of the following software upgrades related mainly with the calorimeter. The document is focused on the cosmic ray positron measurement, covering all the angles related with the topic but the physics behind the excess of positrons observed above 10GeV, since the first step is to evaluate the capability of the detector to get an unbiased positron signal measurement due to proton contamination. Once the theoretical introduction motivates the study of the positron signal and explains the physics behind the detector, the document deals with the performance of the electromagnetic calorimeter and the transition radiation detector, both key subsystems in the suppression of the background of protons, using data from test-beam at fixed energies. A set of electromagnetic cuts in the case of the calorimeter and a likelihood method in the case of the transition detector were used to obtain the electron/proton separation performance of both subsystems. The results demonstrate that the detector upgrade do not interfere in their performance. Besides, a calorimeter calibration method was developed. Finally, a MC simulation of the flight detector configuration, which benefits from the latest software updates, was used to extend the results of the proton suppression to other energies in order to determine and upper limit in the positron measurement without being compromise by any contamination.