Study of the response of the ATLAS Monitored Drift Tubes to heavily ionizing particles and of their performance with cosmic rays

The BIS Monitored Drift Tube (MDT) chambers form the innermost station of the ATLAS Muon Spectrometer and are constructed in Greece by three Universities. The performance of a BIS chamber (Module 0) with cosmic muons has been extensively studied at the University of Thessaloniki. In this work we report on the performance of the chamber, i.e., drift times, resolution, efficiencies as well as gain properties under different high-voltage operating conditions. The experimental results are also confronted with expectations from GARFIELD simulations. A systematic study of the behavior of the ATLAS Monitored Drift Tubes (MDTs) under controlled irradiation by alpha particles has also been performed. The aim of the study was to quantify the response of the drift tubes to alpha particles and consequently to heavily ionizing particles.