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Status of the Forward Muon System

Status of the Forward Muon System. January shutdown activities Trigger rate tests results Planned performance for post shutdown operations. January Shutdown Activities. Major goals for January shutdown Fix existing problems Two planes in MDTs (out of 160) with broken wires

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Status of the Forward Muon System

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  1. Status of the Forward Muon System January shutdown activities Trigger rate tests results Planned performance for post shutdown operations Dmitri Denisov

  2. January Shutdown Activities • Major goals for January shutdown • Fix existing problems • Two planes in MDTs (out of 160) with broken wires • A few PMTs and bases in pixels • Perform checks of system operation • LED calibration • Cosmic counting curves studies • All planned jobs for January shutdown have been accomplished on schedule • Pixels • For ~10 counters PMTs or bases have been replaced • One HV group of 16 counters with HV lower by 100V (type in HV file) has been found and problem corrected • Connections to FE crates have been checked for all counters: 2 mis-cablings found • All HVPS re-calibrated: one full module replaced (HV lower by ~40V) • Comparison of Sr90 response for ~10 counters is compared with Lab F assembly results • Very good agreement observed (within 10%) • LED calibration of all 4214 counters have been performed • Both amplitudes and times stability is well within specifications Dmitri Denisov

  3. Pixels LED Calibration • LED calibration has been performed for all pixels counters • Major goal of such calibration is to check stability of detector operation • Over almost 2 years of operation • Amplitude peak position is stable within ~2-3% (there was step in summer of 2002 due to timing changes) • Amplitude width is stable over last year at ~7% level • Timing peak and width are well within specs: 0.5ns • Summary • All pixel counters perform well Threshold Dmitri Denisov

  4. Mini-drift Tubes During Shutdown • HV system • Fixed HV shorts in two MDT planes • Not unusual problems – two wires broke. This is pretty low failure rate: ~3 wires out of 50,000 over almost two years • Checked calibration of all HVPS: all OK within +-8V • Gas system • Checks of leaks have been performed • No major problems • Overall leak rate is ~8% with spec at 5% • Most of the leaks are in A layer (not accessible for the last 2 years). When A layer will be accessible (planned for summer 2003 shutdown) we will reduce leak rate down to ~4% uniformly distributed over all octants • Gas purification system had glitches over past 3 weeks (due to changes in operating parameters) • Back to normal impurities levels over last few days • One MDC module has been replaced as well as a few ADB cards in order to reduce number of noisy channels • Very high reliability of MDT electronics Dmitri Denisov

  5. MDT Cosmic Counting Curves Studies • Cosmic counting curves studies are performed periodically on all octants to monitor MDT noises and efficiency • January 2003 data demonstrate no measurable changes in MDT noises and gains • Gas gain changes are below ~5% • We do not see signs of the MDT system aging as expected from studies performed during MDT system design Operation Point Dmitri Denisov

  6. Trigger Rate Tests • D0 current plan is to reach ~2kHz Level 1 rate and ~1kHz Level 2 rate by summer 2003 shutdown • Run II specs are (with ~2-3% disables) • Level 1 - 10kHz (factor of ~10 lower for now) • Level 2 – 1kHz (close) • Level 3 – 50 Hz (accomplished) • Last week performed tests of pixels and MDT systems at 2.2kHz of L1 rate (Level 2 system capabilities driven) and 1.0kHz of L2 rate • Pixels performed well for the above rates: L2 busy and L1 busy are well below 1% • MDTs: L1 rate produced no issues for MDT system, but L2 busy at 1.0kHz is ~3-5% • Very low occupancies during tests (cosmic) • Experts are working analyzing where bottleneck is: front ends or readout • At 750Hz MDTs L2 busy is well below 1% Dmitri Denisov

  7. MDTs and Pixels Operation • Our goal is to minimize any changes to operating parameters • Basically no changes, except minor T0 adjustments, over last year • No VME low voltage power supplies failures over last 4 months (out of 36 crates) • Previously rate was ~1 failure per month • Pixels situation • 2 counters out of 4214 are not working (0.05%) • Efficiency of all counter planes is >99% • Minor adjustments to pixels North B layer geometry are planned after January shutdown opening/closing/survey • No signs of counters aging after ~0.2fb-1 accumulated • Pixels efficiency will be monitored on-line in the muon Examine after January shutdown • MDT situation • ~200 wires of 50,000 are not working (0.4%) • Efficiency of all MDT planes is >99% (monitored in muon Examine) • No signs of MDT aging after ~0.2fb-1 accumulated • Looking forward for smooth and reliable operation of the forward muon system long term: thanks for hard work of team of dedicated experts! Dmitri Denisov

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