1. The VDS performance Outline: Current reconstruction / analysis
Alignment
Efficiencies
Monte Carlo
Masking
Usability of runs
Time stability
New / on raw data visible:
The single event killing
Occupancy problems
Occupancy maps on single event level
Summary

2. Alignment, Efficiencies
Done for all periods with hardware changes
Alignment was done synchronised and coordinated for all subdetectors
Produced sets:
9 for pre-November-runs
7 for the data taking period
4 test files: VDS primaries & secondaries agree in data and MC !
Analysis shows: We have to align the VDS more often.
Efficiencies :
In C&A for 30 cases, ready to use
Based on repro3 /repro0
Done per plane
Variations due to hardware changes seen
Unmounted channals seen
2 sets of masks: (open)
20243 (black)

3. Masking, Usability of runs, Time stability
We do not have a masking finer than 1 plane yet operational
Due to hardware problems we have an incomplete list of 4..? Runs where the VDS was not well usable
Investigations of time stability just started
MC / data comparison shows some problems
Time stabilty is beeing
investigated !
R. Wolf, dipl. thesis
Age: 20h !
+ 4 planes unstable !
Dez. min bias runs

4. The single event killing and beyond..
From March meeting:
There was a dynamical, unmonitored occupancy-cut applied in all data
Unknown effect on data. We may have more ‚surprises‘ on tape, and just be blind to them !
=> some parts of your (single) event may be invisible (up to 39 helixes ‚flushed‘)
=> Call it: „Jet supressor“, „generation of missing energy or pt“
No way to recover in ‚mini‘
Relaxing this reveals a ‚new‘ problem: (but seen by SLT)
Occupancies get crazy (SLT confirms)
There are too many wrong-sign
clusters
We can cut but need
to understand
Might even be usefull
=> Test by Friday !

5. Fine Masks
Provide bad channal masks, get rid of „gute Seiten, schlechte Seiten“
=> Single strip cuts are developed and ready for ARTE !
these
are found
easily !
New technique..
.. new surprises: part-time bad HELIXES are good but some chans are bad (always)
these are never OK, but cause sometimes trouble == bad efficiency for the plane or a bad HELIX!
Simply: unmounted !

6. Masking Channals, Summary
Bad channels in VDS: (suggested mask)
plane
chips
chans
bad planes 4 38
4864
number of chans
138240
bad chips 35
4480
number of chips
1080
bad chans
3566
number of planes
119
sum 73
12910 %
3,36
6,76
9,34
First shot might be x2 too strict,
Wait till June 1st !
Alignment will become much easier
The masks quite are stable (single chans !)
Consequences on resolution and efficiency ?
Tests will take place this week !

7. Time stability Micha Time-stability for MB-analysis: Might be Okay
The new findings suggest an even better system
‚Helixes in time‘ might be a small problem

8. From the year 2000 Primary position drifting in run: 4µm/h !
200 µm observed in this season.
The drift can not be corrected with alignment
The IP / beam / target relation is untested
Checks will come (June)

9. Summary For the current analysis, we have
Efficiencies
Alignment (C&A tables for all important time periods existing, not too fine)
MC masks (using C&A, ready to use)
Per run investigations just started
Some problems found & attacked
Unknown systematics due to the ´single event-killer´ => dangerous?
Single strip hit maps show that problematic chans stay stable over time
Some ‚interesting‘, new problmes found
Number of hits in (1..10)% of the events looks crazy
Countermeasure for this found => will be tested with physics soon
Alignment procedure (showstopper was DQ ´by hand´) will improve further
Suggested a procedure for a new repro
We can improve the current situation quite a bit !