Study of the ATLAS-MDT Chambers Performance in the Presence of High Energy Neutron Background Radiation

ATLAS (A Toroidal LHC ApparatuS) is a high energy physics detector that will operate at CERN with proton-proton collisions at energies up to 14 TeV at the Large Hadron Collider (LHC). A stand-alone muon spectrometer covers its outer part, an area of about 5000 m², which will be used for the muon momentum determination. One of the main components of the ATLAS muon spectrometer are the monitored drift tube (MDT) chambers. At the expected LHC luminosity of ~10³⁴ cm^-2s^-1, the MDT chambers will operate in a harsh radiation background, consisting mostly of neutrons and photons in a wide energy range. The aim of this work was the study the MDT chambers\´ performance under the presence of a high neutron and photon background radiation in a wide neutron energy range, produced by the TANDEM Van Der Graaff accelerator of the NCSR "Demokritos". Emphasis was given to the comprehension of all the mechanisms resulting from the presence of the background, with respect to the neutron energy and the MDT materials. The MDT response to neutrons with energies 0.518 to 10 MeV was determined. A simulation model describing the experimental setup with the use of the Geant4 toolkit was developed.