Update on pion and muon showers

Erik van der Kraaij& Przemyslaw Majewski

CERN LCDMay 17, 2010

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 2

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 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– 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 LCD 4

Calorimeter LeakageProblem 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 LCD 5

hCal modules Track of a neutral particle shot at 45°

Gap, which should have been steel

Calorimeter LeakageProblem 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 LCD 6

hCal modules Track of a 100 GeV muon shot at 45°

Gap, which should have been steel

Calorimeter LeakageProblem 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 LCD 7

hCal modules Track of a 250 GeV muon shot at 45°

Gap, which should have been steel

Calorimeter LeakageProblem 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 LCD 8

hCal modules Track of a 350 GeV muon shot at 45°

Gap, which should have been steel

pions shot at φ = 45° , η = 0.21 – AIR GAP

Erik van der Kraaij, CERN LCD 9

(New muon system geometry) Sample of 5000 pions

pions shot at φ = 45° , η = 0.21 – STEEL GAP

Erik van der Kraaij, CERN LCD 10

(New muon system geometry) Sample of 1200 pions

pions shot in all φ directions, η = ~0.21

Erik van der Kraaij, CERN LCD 11

(New muon system geometry) Sample of 1000 pions

pions shot in all φ directions, η = ~0.21

Erik van der Kraaij, CERN LCD 12

(Old muon system geometry) Sample of 1000 pions

muons shot in all φ directions, η = ~0.21

Erik van der Kraaij, CERN LCD 13

(New muon system geometry) Sample of 2000 muons

muons shot in all φ directions, η = ~0.21

Erik van der Kraaij, CERN LCD 14

(Old muon system geometry) Sample of 2000 muons