DD
Dmitri DenisovD0 Beaune Workshop June 2003
D0 Muon System
Sub-detectors Status PDTs
Central Scintillation CountersMDTsPixels
Experience with On-line Data Quality Monitoring
Summary
DD
Dmitri DenisovD0 Beaune Workshop June 2003
Cross-sectional view of the D Run 2 detector.
Forward MDT Layers C B A
A- Counters
Pixel Counter LayersA B C
2T Solenoid
PDT Chambers C B ACosmic Cap Counters
Shielding Shielding
PreshowerFiber Tracker
Silicon Tracker
Electronics
North South
EF
CF
EF
CF
DD
Dmitri DenisovD0 Beaune Workshop June 2003
PDTs – Proportinal Drift Tubes
PDTs is central muon tracking system We have 94 PDTs total with typical size
2x4m2
~6,000 wires total in 10x4cm drift cells Plus electronics to measure drift time
(=muon coordinate)
Total number of disabled wires/channels is ~2%
PDT chambers are rather old (been built in late 80’s)
Have been substantially upgraded (HV, gas, electronics, etc.) for Run II
Currently known issues with PDTs are High dark currents for some of A and B/C
chambers Causing high hits noises as well
Failures of front-end electronics (CB, Control Boards) typically during scraping
Radiation effects? Known un-resolved issues with CB
hardware and firmware Cause mishandling of high multiplicity
events Lack of spare electronics boards and
reliable ways of testing them (not on the working PDTs)
Herman Haggerty is working on PDT wiresDuring Run II upgrade
DD
Dmitri DenisovD0 Beaune Workshop June 2003
Proportional Drift Tubes
What is not yet well under control with PDTs Aging
Painful Run I experience No well developed monitoring in Run II yet
Gas system Monitoring of impurities and their effects on
PDTs operation– Time-to-distance– Aging
Response to problems during operation Team of experts in process of been formed
On-line efficiency monitoring Problems with PDTs over last year
~ 3 weeks of operation with bad front-end code November-December 2002
Better testing of code before going on-line is needed
Efficiency cross checks using other(!) detectors Not perfect T0s for first ~4 months in 2003
Off-line correctable PDT on-line timing monitoring is needed
PDT Efficiency Plot for Typical Physics Run
DD
Dmitri DenisovD0 Beaune Workshop June 2003
Central Scintillation Counters
~1,000 scintillation counters in the central rapidity region
Used to trigger on events with muons
Reject backgrounds (cosmic, beam sprays, etc.)
Muon track reconstruction Running stably
Number of non-working channels is in the 0.1% range
No known issues Planned improvements
A-phi counters thresholds optimization
Monitoring of counters efficiency Monitoring of counters aging Front-end electronics boards
improvements Large voltage drop on a specific fuse
creating “flaky” boards
Cosmic Cap
A-Phi
DD
Dmitri DenisovD0 Beaune Workshop June 2003
Mini-Drift Tubes
MDTs is muon tracking detector in the forward rapidity region
50,000 wires and electronics channels Built for Run II 1x1cm2 drift cell with maximum electron drift
time of 60ns Stable operation over last 2 years
Number of non-working channels is ~0.4% ~0.2% are due to electronics boards (noise,
failures, etc.) ~0.2% are due to detectors (HV noise,
broken wires, etc.) A layer MDTs are operating for 2.5 years without
single access Space flight reliability!
Last changes to MDT operating parameters (delays, thresholds, etc.)
Autumn 2001 No known issues
It takes considerable amount of efforts to keep such large system working stably
Power supplies/fuses replacements (more then 1000 fuses in the system!)
Noisy wires disabling Planned improvements
Access to A layer during August shutdown Minor gas leaks Electronics repairs
MDT A Layer
DD
Dmitri DenisovD0 Beaune Workshop June 2003
Mini-Drift Tubes
On-line monitoring for MDTs is well developed and all issues have been quickly detected
Examine, alarms, monitoring GUIs Noisy channels Failure of detector elements, HV, electronics
In addition to daily monitoring by shifters Daily checks by experts Weekly experts checklists
About 20 pages of data Periodic experts maintenance
During shutdowns
MDT Planes Efficiency
MDT Coordinate resolution is ~0.7mm
DD
Dmitri DenisovD0 Beaune Workshop June 2003
Forward Trigger Counters (Pixels)
Designed and built for Run II ~5,000 scintillation counters and electronics Arranged in R- geometry for triggering 3 layers: A, B and C
Operating smoothly since beginning of Run II Typical number of dead channels is ~0.1% Last changes to operating parameters (trigger
gate width) Late 2001
Stability of timing measurements Intrinsic is ~0.2ns
Can see drift of accelerator clock by ~2-3ns over a year
Time resolution is well in agreement with expectation at ~1.8ns
Known problem Reliability of VME power supplies in the hall
Radiation damage during scraping About once per month – loosing ~8% of coverage
during affected store New supplies ordered, plan to replace all of them
(~50% already replaced) within ~2 months
C layer Pixels plane
DD
Dmitri DenisovD0 Beaune Workshop June 2003
Forward Trigger Counters
On-line monitoring for Pixels is well developed and all problems have been easily detected
Examine, alarms, monitoring GUIs Failure of detector elements, HV, electronics
In addition to daily monitoring by shifters Daily checks by experts Weekly experts checklists
About 10 pages of data Periodic experts maintenance
During shutdowns
On-line Efficiency Monitoring
1 year timing stability
Mean=0.24ns=0.6ns
Pixels Timing Distributions
DD
Dmitri DenisovD0 Beaune Workshop June 2003
On-line Muon Quality Monitoring and Operations
What works well Check lists
Shifters/experts filling check list Examine plots
Most of problems are easy to detect (see failed PDT in efficiency plot above) Alarms
Most serious problems (HV trips, power supplies trips, etc.) are pausing physics runs GUI (readout, RMIs, etc.)
Provide info about problems (crate our of synchronization, gas flow fluctuations, etc.)
Even “resolve” minor problems (readout GUI)
What could and should be improved Understanding of PDTs
Even experts are having problems with some of the cases Better monitoring for PDTs
On-line efficiency – Why fluctuating?– Normalized to tracks found in other sub-systems
Well defined and optimized list of alarms Notes of what to do in the case of alarms to be added
Reliability of pixels VME crates power supplies Reference plots for Examine Availability of spare electronics boards Better communication between Global Monitor, Off-line monitoring and Muon
shifters/Experts
We need more dedicated groups/collaborators in order to resolve existing problems, develop better monitoring tools and support muon system operation!
DD
Dmitri DenisovD0 Beaune Workshop June 2003
Summary
Muon system operating reasonably well over last year and there are no serious known problems affecting physics capabilities of the D0 detector
There is well defined plan of improvements Reliability of the muon system elements Monitoring tools Better understanding of how detectors/electronics work
– Especially PDTs System is large and complex with over 100k channels of detectors and
electronics Groups of dedicated experts are working hard to keep system running stably We do need extra help for long term operation and improvements in data quality
There are interesting new results already coming and expected to come based on D0 muon system
100’s of thousands of J/Psi’s! Close to 10k of Z’s And coming…
Opposite sign high Pt di-muon mass plot