Preliminary studies on Preliminary studies on Muon System Muon System

software alignmentsoftware alignment

LHCb week CERN May 29-th, June 2-nd 2006

Stefania Vecchi INFN Bologna Wander Baldini INFN Ferrara

Stefania Vecchi & Wander Baldini

LHCb Week 29 May - 2 June 2006 2

Muon system misalignmentsMuon system misalignments

• Muon Chambers will be positioned on the support structure within few mm from the ideal position

• A muon system misalignment will effect mainly the L0 trigger (Pt measurement & muon candidate selection). It might have a smoother impact in the analysis (Particle ID).

• With MonteCarlo simulations we can evaluate the effects of a misalignment:– Of the whole detector with respect to the others;– Of M1 respect M2-M5;– Of each station;– Of single chambers in the most critical regions in order to

better define the positioning accuracies limits

• We use the L0muonTrigger routines to evaluate trigger performances. They allow changes in FOI or Pt cut, but not in single chamber position

Stefania Vecchi & Wander Baldini

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First studiesFirst studies• Pt calculation of each muon Candidate Changed in Tower.cpp

(L0muonKernel) due to shift in M1 or M2 • Study of L0muon trigger performances as a function of

misalignment scale: efficiency to signal, Mbias retention, charge asymmetry

• ONLY effects of L0 performances on Pt calculation can be evaluated no FOI

• Settings:– Default FOI X/Y: M1=±5/0 M2= ± 3/0 M4= ± 3/1 M5= ±3/1 – Pile Up rejection– L0muon Trigger output rate: 125 KHz

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Data sample / DaVinciData sample / DaVinci

• In order to use L0mAnalysis package we used RTTC data sample generated by D.Perego– Minimum Bias: 25000 events– BsJ/25000 events– DaVinci v14r4– L0mAnalysis v4r4– L0mTrigger v3r0

• Run L0mTrigger introducing a shift on M1 and M2 x-coordinate (+-0.5 cm, +-1cm, +-5cm, -10cm)– Affect Pt calculation – No muon candidates losses due to FOI– Introduce charge asimmetry

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No-ShiftNo-Shift

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Shift M1Shift M1 -0.5cm -0.5cm

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Pt cut and Pt cut and efficiency efficiency almost almost unchanged unchanged

Charge Charge asymmetry asymmetry 20%20%

Shift M1Shift M1 -1.0 cm -1.0 cm

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• Need higher Pt cut toNeed higher Pt cut to keep 125 kHz ratekeep 125 kHz rate

• Efficiency drops Efficiency drops

• Higher MB retentionHigher MB retention

• Big ChargeBig Charge asymmetry asymmetry

Shift M1Shift M1 -5.0 cm -5.0 cm

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Shift M1Shift M1 -10.0 cm -10.0 cm

Almost only one Almost only one charge leftcharge left

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Shift M2 Shift M2 +0.5cm+0.5cm

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Shift M2 Shift M2 +1.0 cm+1.0 cm

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Slightly different from M1 shift results (geometry)

Shift M2 Shift M2 +5cm+5cm

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Preliminary performances Preliminary performances summarysummary

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Next studiesNext studies

• Repeat the study on L0m trigger performances on DC06 ( generated aligned) data with different misaligned geometries (changing geometry DB) @ reconstruction level.– In this way also effects on FOI can be taken into

account.– Need to ask officially for data production?

(L0 studies for TDR: 500K mbias + 30K Bs->J/)

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ConclusionsConclusions

• The machinery to see effects of the misalignment is working, now more quantitative studies will start (0.5 – 5.0 cm

• Given the big amount of combinations, for the moment we will focus mainly on M1-M2-M3 regions

Stefania Vecchi & Wander Baldini

LHCb Week 29 May - 2 June 2006 16

sparesspares

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L0/reconstruction @ nominal position

Detector @ nominal position

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L0/reconstruction response misaligned

Detector misaligned

M1 M2 M3 M4 M5

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Detector Granularity and readout Detector Granularity and readout

M1 M2 M3 M4 M5

R1

1x2.5 1x2.5 GEMGEM

0.6x3.1 0.6x3.1 mixed r/omixed r/o

0.67x3.4 0.67x3.4 mixed r/omixed r/o

2.9x3.62.9x3.6 cathode r/ocathode r/o

3.1x3.93.1x3.9 cathode r/ocathode r/o

R2 2x52x5 GEMGEM

1.3x6.31.3x6.3mixed r/omixed r/o

1.35x6.81.35x6.8 mixed r/omixed r/o

5.8x7.35.8x7.3 cathode r/ocathode r/o

6.2x7.7 6.2x7.7 cathode r/ocathode r/o

R3 4x10 4x10 cathode r/o cathode r/o

2.5x12.52.5x12.5 cathode r/ocathode r/o

2.7x13.52.7x13.5 cathode r/ocathode r/o

11.6x14.511.6x14.5 cathode r/ocathode r/o

12.4x15.512.4x15.5 cathode r/ocathode r/o

R4 8x208x20 wires r/owires r/o

5x25 5x25 wires r/owires r/o

5.4x27 5.4x27 wires r/owires r/o

13.1x2913.1x29 wires r/owires r/o

24.8x30.924.8x30.9 wires r/owires r/o

Pad Dimension(cm2)

Chamberreadout