Muon chamber efficiencies and muon identification

1. Muon chamber efficienciesand muon identification Andrea Venturi INFN Pisa thanks to Tommaso Boccali Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

2. Introduction • In ALEPH muon identification relies on the tracking capability of HCAL and Muon chambers • HCAL: at least 40-50% of fired hits (out of ~23) • Muon-ch: at least one hit (out of 4) • HF/LEP1 muon id: HCAL and Muon-ch • LEP2 muon id: HCAL or Muon-ch Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

3. Simulation • Simulation of the digital readout is strongly correlated with the simulation of the muon identification • Digital readout efficiency  muon id efficiency • Digital readout was relatively fragile and almost impossible repairing it during data taking • Digital readout efficiency was not always stable and as high as possible. • How is the simulation done: • single HCAL/muon-ch layer efficiency measured with di-muons events (lack of statistics at LEP2) and hits are randomly deleted in MC events to reproduce the measured efficiencies • done on a year by year basis • NO correlation among planes is taken into account • inefficiencies are distributed uniformly in the whole HCAL/muon-ch plane Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

4. Where we are now • Tommaso released the new muon chamber efficiency banks (MCPE) for 1997-2000 • They replace almost dummy banks used so far: • 1994 efficiencies + ad hoc corrections for known damaged chambers • Measured with di-muon events  mainly Z calibration run • are they representative of the mean muon-ch efficiencies ? • Check done: • Muon-chamber efficiencies measured with 2 photon events • better distributed in time • low momentum • mainly in the endcaps • Muon-chambers occupancy maps • We decided that efficiencies measured with di-muons events are good enough. • HCAL final efficiencies: to be done !! Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

5. What I’m going to talk about Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

6. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

7. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

8. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

9. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

10. A test • Sensitivity of the muon identification efficiency on the muon chamber efficiencies • I have used different muon chamber efficiency banks to analyze the same sample of di-muon MC events at Z peak (300k) • Used efficiency banks • 1994 • 2000 old (dummy) version • 2000 new (Tommaso) version • all layers of all chambers 90% efficient • all layers of all chambers 60% efficient • Useful to: • give us a reference on the requested accuracy to build the efficiency banks • give us an indication on how likely is the possibility that the observed data vs MC discrepancy are due to innacurate muon chamber efficiency mapping • BE CAREFUL: this test does NOT say anything about the intrinsic approximation of the efficiency simulation algorithm • no corralations, spread inefficiencies... Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

11. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

12. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

13. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

14. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

15. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

16. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

17. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

18. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

19. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa

20. Muon-ch efficiencies- Andrea Venturi - W meeting in Pisa