Digitalizador de forma de onda e aquisição de dados em um detector de radiação Cerenkov em água

In this work the development of a data acquisition system with waveform digitizatin is presented, for use in a water Cerenkov radiation detector. The system basic function is to encode the signal produced by cosmic rays in a detector assembled at the Detection Systems Laboratory, in CBPF. Some theoretical topics related to the analysis, observation and detection of cosmic rays are also presented. The detector is a reduced version of the model used in the Pierre Auger Project. This project is held by an international collaboration and is devoted to the study of ultra-energetic cosmic rays (energy >1019 eV ) that reach the Earth surface. The digitizer circuit makes use of an analog-to-digital converter operating at sampling rate of 65 MHz, 1 Vpp input range and 9 bits resolution. The reading and storage system is composed by a FIFO (First-In First-Out) memory and a control circuit implemented in a single FPGA (Field Programmable Gate Array) chip. The digitized signal is read by a data acquisition program which stores data in the memory of a personal computer and estimates signal parameters such as amplitude, charge, rise time, fall time, width and baseline. Measurements have been carried out using the developed system. The results have been compared to data acquired with a digital oscylloscope, as well as with a multichannel analyser. The analysis of the obtained results has allowed us to characterize and to improve the system performance.