# Presentation: 908219

## Week of September 23 to September 29 D0 Summary

- Delivered luminosity and operating efficiency
- Delivered: 2.8pb-1
- Recorded: 1.6pb-1 (~60%)
- Data taking efficiency
- no major hardware/software problems
- lower, then typical
- short stores have initial inefficiency
- Issues caused ~1+ hours downtime
- Silicon readout and HV trips
- CFT readout and downloads
- Calorimeter SBC failure
- Muon Level 1 trigger crate failure
- Special runs
- Accelerator halo
- reasonable
-  Beam position
- stable within 0.3mm from the detector center

- Dmitri Denisov

## Progress with Detectors/Triggers

- Experiment “timing change” happened during studies period last week
- while Level 1 trigger decision is delivered to front-ends they are “holding” full information about an event in their memories
- called “pipelines”
- D0 Level 1 decision time is designed  to be 3.6 microsec
- at the beginning of Run II Level 1 decision time was set on a “lower side”
- was “doable” without fiber tracker Level 1 trigger
- after modifications to fiber tracker electronics/trigger
- L1 latency was increased by 264ns
- all detectors had to modify their timing (pipeline depth)
- went reasonably smoothly
- fiber tracker required 2 short accesses for firmware modifications
- all systems performed timing change and verified operations
- Two major issues fixed in  the muon system last week
- Level 2 trigger code bug was fixed which drastically (factor of 50) reduced number of Level 2 code crashes
- problems with muon readout crates accepting events while still processing previous one was resolved
- muon data “integrity” problems are down to 10-5 level from 10-3 level
- Clear path for even higher trigger rates established
- Level 1 trigger rate of 1kHz looks reasonable with no modifications
- L2 trigger rate is planned to be increased to 0.5 kHz as soon as extra trigger nodes are “burned in”
- this is starting to be very close to baseline Run II D0 design

- Dmitri Denisov

## Data Taking and Triggering

- Running physics trigger list 8.3
- designed for luminosity in the range (5-40)1030
- keeping high pt triggers un-prescaled at any luminosity
- After improving stability in trigger/DAQ over month we are able to set new trigger rates guidelines  (~1.5-2 times above trigger version 8.2)
- L1 trigger ~0.5kHz
- L2 trigger ~0.2kHz
- L3 trigger (to tape) ~50 Hz
- Total number of events collected over last week
- 4mln
- Farms reconstruction progress and plans
- burn in of the nodes on progressing on schedule
- expecting considerable increase in reco farms reconstruction rate within ~2 weeks
- Level 3 farms is awaiting 40 new nodes under burn in now - will ~double Level 3 trigger processing power

- Dmitri Denisov

## Calorimeter Preamplifiers Cooling

- Last week D0 lost cooling in one of the calorimeter preamp boxes
- as a result temperature of the cooling air increased from 40degC to 69degC
- close to klixon power shut off limit
- affects preamps performance and lifetime
- 3 sensors inside the box all measure elevated temperatures
- affects ~4% of calorimeter channels
- 12% of central calorimeter channels
- We tried multiple options to fix this issue without access
- box is located in the “cathedral area”
- turned power to preamps off
- quick temperature reduction to 21degC
- power cycled braker feeding power to fans - no change
- Most probably failure of the cooling fan(s)
- all fans replaced for Run II
- have had one similar failure last year
- 2 fans failed
- “bushing” style while labeled/ordered as “ball bearings”
- Repairs require major efforts
- 4 hours each to open and close 1,000 tons muon magnets
- 4-8 hours to disassemble  box and replace failed fan(s)

- Prototype Preamp Box

- Dmitri Denisov

## Summary

- D0 experiment is progressing well with physics data taking
- trigger list 8.30 is running on-line
- 4 mln events collected last week
- Weekly data taking efficiency over last month is stable at ~65% level
- quite a few runs have efficiency above 90%
- Further increase in off-line data processing power as well as Level 1 and Level 2 trigger bandwidth is expected soon
- Failure of the cooling system for the calorimeter preamplifiers requires access
- 12-16 hours in duration, including detector opening/closing
- currently scheduled to start at 6am on Wednesday, October 2nd
- expect to be ready for S&S between 6pm and 10pm
- will provide better estimate about progress of repairs by noon Wednesday

- Dmitri Denisov