1. Preliminary studies on Muon System software alignment LHCb week CERN May 29-th, June 2-nd 2006 Stefania Vecchi INFN Bologna Wander Baldini INFN Ferrara

2. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 20062 Muon 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

3. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 20063 First 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

4. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 20064 Data sample / DaVinci In order to use L0mAnalysis package we used RTTC data sample generated by D.Perego –Minimum Bias: 25000 events –B s  J/          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

5. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 20065 No-Shift

6. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 20066 Shift M1 -0.5cm

7. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 20067 Pt cut and efficiency almost unchanged Charge asymmetry 20% Shift M1 -1.0 cm

8. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 20068 Need higher Pt cut to Need higher Pt cut to keep 125 kHz rate keep 125 kHz rate Efficiency drops Efficiency drops Higher MB retention Higher MB retention Big Charge Big Charge asymmetry asymmetry Shift M1 -5.0 cm

9. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 20069 Shift M1 -10.0 cm Almost only one charge left

10. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 200610 Shift M2 +0.5cm

11. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 200611 Shift M2 +1.0 cm

12. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 200612 Slightly different from M1 shift results (geometry) Shift M2 +5cm

13. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 200613 Preliminary performances summary

14. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 200614 Next 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 B s ->J/  )

15. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 200615 Conclusions 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

16. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 200616 spares

17. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 200617 L0/reconstruction @ nominal position Detector @ nominal position Real situation Simulated situation L0/reconstruction response misaligned Detector misaligned M1 M2 M3 M4 M5

18. Stefania Vecchi & Wander Baldini LHCb Week 29 May - 2 June 200618 Detector Granularity and readout M1M2M3M4M5 R11x2.5 GEM GEM0.6x3.1 mixed r/o 0.67x3.4 2.9x3.6 cathode r/o 3.1x3.9 R22x5 GEM GEM1.3x6.3 mixed r/o 1.35x6.8 5.8x7.3 cathode r/o 6.2x7.7 R34x10 cathode r/o 2.5x12.5 cathode r/o 2.7x13.5 cathode r/o 11.6x14.5 cathode r/o 12.4x15.5 cathode r/o R4 8x20 wires r/o 5x25 wires r/o 5.4x27 13.1x29 24.8x30.9 wires r/o Pad Dimension (cm 2 ) Chamber readout