1. Update on pion and muon showers Erik van der Kraaij & Przemyslaw Majewski CERN LCD May 17, 2010

2. Problems from last meeting Distributions of hit distance to PFO direction with ‘weird’ peaks. Why are the hits in the muon chambers so far away? And so many per chamber? How come there is a (low) energy dependent calorimeter leakage to the muon system? Erik van der Kraaij, CERN LCD2

3. Hit distances Weird peaks were caused by vector/array problems. Distributions are now as can be expected. Coarser granularity of hCal compared to eCal – eCal distr peaks at ~20mm, – hCal distr peaks at ~50mm. Difference between old and new muon geometry is caused by material used. – Old: RPCgas – New: scintillator. Erik van der Kraaij, CERN LCD3

4. Hit distances Weird peaks were caused by vector/array problems. Distributions are now as can be expected. Coarser granularity of hCal compared to eCal – eCal distr peaks at ~3mm, – hCal distr peaks at ~13mm. Difference between old and new muon geometry is caused by material used. – Old: RPCgas – New: scintillator. Erik van der Kraaij, CERN LCD4

5. Calorimeter Leakage Problem was caused by crack. Each 22.5° there is a steel plate in the r-z plane between two hCal modules. But: the gap was AIR, not steel in the Mokka simulation. Because of the 10mrad Lorentztransformation in the settings for the beamcrossing angle a neutral particle shot at 45° in the transverse plane does not go through the crack. Charged particles in a certain energy range can exactly make it. Erik van der Kraaij, CERN LCD5 hCal modules Track of a neutral particle shot at 45° Gap, which should have been steel

6. Calorimeter Leakage Problem was caused by crack. Each 22.5° there is a steel plate in the r-z plane between two hCal modules. But: the gap was AIR, not steel in the Mokka simulation. Because of the 10mrad Lorentztransformation in the settings for the beamcrossing angle a neutral particle shot at 45° in the transverse plane does not go through the crack. Charged particles in a certain energy range can exactly make it. Erik van der Kraaij, CERN LCD6 hCal modules Track of a 100 GeV muon shot at 45° Gap, which should have been steel

7. Calorimeter Leakage Problem was caused by crack. Each 22.5° there is a steel plate in the r-z plane between two hCal modules. But: the gap was AIR, not steel in the Mokka simulation. Because of the 10mrad Lorentztransformation in the settings for the beamcrossing angle a neutral particle shot at 45° in the transverse plane does not go through the crack. Charged particles in a certain energy range can exactly make it. Erik van der Kraaij, CERN LCD7 hCal modules Track of a 250 GeV muon shot at 45° Gap, which should have been steel

8. Calorimeter Leakage Problem was caused by crack. Each 22.5° there is a steel plate in the r-z plane between two hCal modules. But: the gap was AIR, not steel in the Mokka simulation. Because of the 10mrad Lorentztransformation in the settings for the beamcrossing angle a neutral particle shot at 45° in the transverse plane does not go through the crack. Charged particles in a certain energy range can exactly make it. Erik van der Kraaij, CERN LCD8 hCal modules Track of a 350 GeV muon shot at 45° Gap, which should have been steel

9. pions shot at φ = 45 °, η = 0.21 – AIR GAP Erik van der Kraaij, CERN LCD9 (New muon system geometry) Sample of 5000 pions

10. pions shot at φ = 45 °, η = 0.21 – STEEL GAP Erik van der Kraaij, CERN LCD10 (New muon system geometry) Sample of 1200 pions

11. pions shot in all φ directions, η = ~0.21 Erik van der Kraaij, CERN LCD11 (New muon system geometry) Sample of 1000 pions

12. pions shot in all φ directions, η = ~0.21 Erik van der Kraaij, CERN LCD12 (Old muon system geometry) Sample of 1000 pions

13. muons shot in all φ directions, η = ~0.21 Erik van der Kraaij, CERN LCD13 (New muon system geometry) Sample of 2000 muons

14. muons shot in all φ directions, η = ~0.21 Erik van der Kraaij, CERN LCD14 (Old muon system geometry) Sample of 2000 muons