# Presentation: 208672

## Status of the Forward Muon System

- January shutdown activities
- Trigger rate tests results
- Planned performance for post shutdown operations

- Dmitri Denisov

## 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

## 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

## 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

## 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

## 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

## 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