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

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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

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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

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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

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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

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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

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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

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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

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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!

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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