Update on pion and muon showers

1. Update on pion and muon showers Erik van der Kraaij & PrzemyslawMajewski 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 LCD

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 • eCaldistr peaks at ~20mm, • hCaldistr peaks at ~50mm. • Difference between old and new muon geometry is caused by material used. • Old: RPCgas • New: scintillator. Erik van der Kraaij, CERN LCD

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 • eCaldistr peaks at ~3mm, • hCaldistr peaks at ~13mm. • Difference between old and new muon geometry is caused by material used. • Old: RPCgas • New: scintillator. Erik van der Kraaij, CERN LCD

5. Calorimeter Leakage Gap, which should have been steel 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. hCal modules Track of a neutral particle shot at 45° Erik van der Kraaij, CERN LCD

6. Calorimeter Leakage Gap, which should have been steel 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. hCal modules Track of a 100 GeVmuon shot at 45° Erik van der Kraaij, CERN LCD

7. Calorimeter Leakage Gap, which should have been steel 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. hCal modules Track of a 250 GeVmuon shot at 45° Erik van der Kraaij, CERN LCD

8. Calorimeter Leakage Gap, which should have been steel 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. hCal modules Track of a 350 GeVmuon shot at 45° Erik van der Kraaij, CERN LCD

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

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

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

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

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

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