Study on the optical fiber attenuation of the UMD using the integrator channel

J. DE JESÚS; J. M. FIGUEIRA; F. SÁNCHEZ

Otro; Pierre Auger Internal GAP Note 052 (2021); 2021

Pierre Auger Internal GAP Note 052 (2021) /// In this GAP note, the attenuation in the optical fiber of the modules of the Underground Muon Detector (UMD) is studied using two datasets: ADC calibration files and shower events. For both cases, the mean charge generated by a single muon was obtained for each scintillator strip. This observable presented a clear anti correlation with the fiber length of the strip, which is consistent with the expectations from extrapolations of laboratory measurements. An effective attenuation length was obtained for both datasets by the means of an exponential fit, showing good agreement between them and with the laboratory. Finally, charge values of the single-muon signal obtained with the calibration files were found to be systematically higher than those in the shower events. This is consistent with ADC calibration files being biased towards muons with larger zenith angles.