Forward muon system for the D0 detector upgrade

The design and main parameters of the completely redesigned DO Forward Angl e MUon System (FAMUS: 1.0 < \eta\ < 2.0) for the next high luminosity Tevat ron Collider run are reported. Results of the studies of trigger scintillat ion counters based on fast scintillator Bicron 404A and WLS bars SOFZ-105 a re presented. We report about results of test beam studies of prototype cou nters including minimum ionizing particles detection efficiency, time resol ution and amplitude response. Radiation ageing of scintillating materials f or the doses up to 1 Mrad, phototubes magnetic shielding in the fields of u p to 700 G and ageing of phototubes are presented. Mini-Drift Tubes (MDTs) are chosen as FAMUS tracking detectors. The detector is a drift wire chambe r with a metallic cathode. The detector operates in proportional mode with a fast freon-methane gas mixture to provide high drift velocity, adequate c ounting rate and low ageing. A description of the performance of the MDT is given. Studies of two prototypes in test beams were performed at FNAL and JINR. Obtained coordinate accuracy is around 0.5 mm r.m.s. All tests show r obustness of MDT as tracking detector of the new muon system for a long per iod in high DO background radiation conditions. (C) 1998 Elsevier Science B .V. All rights reserved.