# Presentation: 432249

## D0 Data Taking Summary: March 1 to March 7

- Luminosity
- Delivered 9.9pb-1
- Recorded 7.6pb-1
- Data taking efficiency
- 77% weekly
- Backgrounds
- P and pbar halo are within specs
- Beam position
- Within specs
- Number of events collected
- 14mln

- Dmitri Denisov

## Calorimeter and Muon Noise

- Since late Sunday, February 29th (should not we skip February 29ths ?)
- New never before seen type of noise affected D0 calorimeter and muon system

**Calorimeter**
**On-line plots**

**Muon Hits Plot**

- Dmitri Denisov

## Source of Noise?

- The noise have been detected quickly and by Monday we learned
- Physics data taking is badly affected
- Considerable number of events have clear signature of noise
- Noise is correlated with toroid magnet been turned ON or OFF
- Noise starts at ~250A current in toroid coils
- Nominal current is 1500A
- Noise is coming from noisy power supply?
- Noise is coming from failed power supply filtering capacitors?
- Noise is coming from another D0 component which is affected by fringe magnetic field?

- Dmitri Denisov

## Data Taking

- Mostly stable physics data taking without major problems
- Largest sources of downtime
- Fast dump of solenoid magnet on Tuesday
- Operator mistake, lost ~1.5 hours – long term resolved
- Problems during Sunday morning store start
- Level 2 muon system issues, ~1 hour lost – plan for long term solution in place
- All other issues been resolved on a time scale of below ~20 minutes
- 129 hours in stores
- 124 hours of data taking
- One access request
- Forward proton detector power supply failure - fixed

- Dmitri Denisov

## Do D0 Detectors Observe Radiation Aging?

- After 3 years of data taking and ~10% of expected Run II luminosity delivered it is time to (re)evaluate situation with radiation aging
- Should not get missed among multiple other tasks D0 is performing
- D0 has experienced painful muon drift chambers aging issues during Run I
- ~50% of chambers not used for physics analysis
- Use of un-tested organic materials during construction
- Aging effects seen with charges as low as ~1mC/cm
- Closest to the interaction region chambers have electrodes replaced (~20%) for Run II
- Other chambers have higher flow rate and gas filtering in re-circulation system
- Run II shielding reduced particle fluxes by factor of ~10 per unit of delivered luminosity
- Fast heating of the wires method is developed to “clean” the wires
- Lessons (D0 plus other detectors)
- Radiation aging is very dangerous – you can damage your detector badly
- There are un-expected issues with detectors aging which are very difficult (impossible?) to test before real data taking
- Neutron doses vs gamma doses, etc.
- We have to constantly monitor for signs of “aging” and act well in advance before problems become severe

- Dmitri Denisov

## Radiation Aging

- Major questions to be answered
- What is currently total integrated dose for the “hottest” part of the sub- detector?
- Could be in rads, or in charge/unit of wire for gas detectors
- Should be normalized by total delivered luminosity
- Direct measurements (TLDs, currents) or MC simulation
- What are doses when detector performance expected to start to deteriorate
- Based on manufacturers specs
- Based on studies
- Are we getting close?
- Do we actually observe any changes in detectors performance – critical!
- For example
- Number of phe per mip in the case of fiber tracker
- Will have a series of presentations from D0 about detailed status of radiation aging starting from silicon detector next week

- Dmitri Denisov

## D0 Detectors Radiation Aging Summary

- .

- Dmitri Denisov

## D0 Summary

- Smoothly collecting physics data
- Data taking efficiency last week is good ~87%
- Almost 10 pb-1 recorded
- Best day in terms of recorded luminosity – during record store on Thursday
- Problems affected data taking are all understood and resolved
- This week is D0 collaboration meeting (at Fermilab)
- Major focus is physics analysis for coming winter and summer conferences
- Data samples well above Run I
- Detectors are more complex then in Run I – more time/efforts needed to understand them well
- Many interesting results are coming
- 66 talks during Sunday –Tuesday D0 Physics Workshop this week!

- Dmitri Denisov