# Presentation: 078070

## Week of September 2 to September 8 D0 Summary

- Delivered luminosity and operating efficiency
- Delivered: 3.9pb-1
- Recorded: 2.4pb-1 (~62%)
- Data taking efficiency
- no major hardware/software problems
- during Sunday our “to tape” efficiency was stable at ~73%
- different problems caused 1-2 hours downtimes
- Silicon readout problems
- Failure of muon PDT LVPS
- Often CFT downlaads
- L2 muon inputs loss of synchronization
- Accelerator halo
- reasonable
-  Beam position
- stable within 0.3mm from the detector center

- Dmitri Denisov

## Data Taking During Global Runs

- Typical global physics run duration is 2 hours
- During global run ~20% of time is used for
- reset synhronisation between front-ends and trigger framework (SCL)
- HV trips in silicon
- re-download of front-end crates for fiber tracker
- Working on
- fixing some problems
- reducing effect of another problems by developing quick recovery procedures
- Our goal over next few months to get to rate to tape efficiency of 75%

- Dmitri Denisov

## D0 Detectors Status

- Luminosity detector
- Stable operation
- Estimated luminosity measurement error is 10%
- Silicon detector
- Power supplies are running well - no problems for 3 months!
- Noises stable: ~94% of channels are in operation
- Fiber tracker
- Stable operation with all channels in readout
- Major issue is  hot/empty groups of channels
- in progress of studying this issue
- Calorimeter
- Stable
- Different sources of low energy noises are under investigation
- Muon
- Stable operation
- Major issue is “data integrity”
- on the 10-3-10-4 level there is mismatch between portion of event collected from different crates
- Forward proton detector
- inserting pots during most stores

- Dmitri Denisov

## He Concentration in the Hall

- D0 operates ~7,000 phototubes in the collision hall
- He has high coefficient of diffusion through the glass
- at ~ a few ppm level He concentration inside the phototube could affect tube parameters badly
- afterpulses
- gain loss
- with concentration of He in the hall of ~20ppm (x4 natural level) the tubes lifetime is estimated at ~30 years
- D0 measured He levels a few times during last few months and level was in the 10-20ppm level
- Late August we discovered that He level elevated to ~600-900ppm
- the actual reason for the raise is not understood (TeV quenches?)
- source of He traced to air flow from the tunnel into the hall
- three items helped to resolve this issue
- extra sand bags in the tunnel
- special “curtains” between D0 and the tunnel
- pressure in the hall is increased to stay above tunnel pressure
- Over last week He levels in the collision hall are stable at ~20ppm
- He concentration in the tunnel is still high at ~1000-2000ppm
- forward proton detector PMTs?

- Dmitri Denisov

## Data Taking and Triggering

- Running physics trigger list 8.2
- designed for luminosity in the range (5-25)1030
- keep high pt triggers un-prescaled at any luminosity
- addition of new tools which became available recently
- tracking at the Level 3 trigger
- Typical trigger/DAQ rates
- L1 trigger 0.3-0.35kHz
- L2 trigger 0.15-0.2kHz
- L3 trigger (to tape) ~50 Hz
- Total number of events collected over last week
- 6.7 mln
- Reco reconstruction speed is improved with new version 11.11
- processed about 4 mln events per week

- Dmitri Denisov

## Summary

- D0 Collaboration is progressing well with physics data taking
- no major problems with detectors/electronics/triggers/DAQ
- all detectors are in readout
- trigger list 8.20 is running on-line
- collected ~6.7 mln. events during last week
- average data taking efficiency is ~65% over a week, ~75% over a “good” day, and ~85% for a “good” run
- working on short and long term programs how to increase above numbers without compromise of the quality for the data we collecting

- Dmitri Denisov