Comparison of AHCAL hadron shower data with simulations Shaojun Lu - PowerPoint PPT Presentation

Comparison of AHCAL hadron shower data with simulations Shaojun Lu shaojun.lu@desy.de LCWS10, Beijing, 26-30 March 2010

Outline • Test beam prototype • The power of imaging calorimeter • Validation with em showers • Comparison of hadron shower data with simulations ‣ Longitudinal shower profile ‣ Transverse shower profile ‣ Transverse shower containment ‣ Mean shower radius ‣ Leakage • Summary Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 2

Test beam prototype • 38 steel layers, 4.5 λ • 7608 tiles with SiPMs 1x1 mm 2 SiPM • Test at CERN 2006-07, FNAL 2008-09 • Energies: 1 GeV - 180 GeV • Particles: π ± , e ± , p, µ Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 3

The power of imaging calorimeter • The high granularity of the calorimeter allows detailed 3D studies of the substructure of hadronic showers • Minimum ionising track segments can be identified and used as a calibration tool • Highly granular readout provides detailed 3D information on hadronic showers to constrain shower models • Strong support for particle flow algorithm Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 4

Validation with em showers • Use electron data no ECAL in front to validate detector understanding and calibration Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 5

Validation with em showers • Simulation includes p.e. statistics, SiPM non-linearity, electronic noise, light cross talk between tiles, and overlaid hits from random trigger events. • Stochastic: data: a = 22.5 ± 0.1(stat) ± 0.4(syst)[%/ √ E] MC: a = 20.4 ± 0.2(stat)[%/ √ E] Non-linearity < 4% @ 50GeV, • Constant term: and improving ... data: b = 0 ± 0.1(stat) ± 0.1(syst)[% / √ E] MC: b = 0 ± 0.6(stat) [% / √ E] • c fixed to ~ 60MeV (pedestal events) Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 6

Two dimensional profiles • Two dimensional radial energy density for 10 GeV negative pion showers • Transversal radial ring with center r, and longitudinal position z Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 7

Position of shower start • Position of shower start in the calorimeter as a function of the number of interaction lengths • Longitudinal shower profile in the calorimeter determined before and after the shift, event by event, to the shower starting point Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 8

Longitudinal shower profile - data and MC • From shower start ➡ identification of the shower start, comparison of profiles to simulations without fluctuation of start position • Agreement between data and simulation around 20% • Most of the time, simulation above data in the shower core but below in the tails Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 9

Monte Carlo Simulation models list LHEP (diff. energy scale) � LEP HEP FTFP_BERT_TRV BERT FTFP QGSP_BERT BERT QGSP LEP QGSP_FTFP_BERT BERT FTFP QGSP FTF_BIC FTFB BIC Energy in [GeV] • Discrepancies spotted depending on model, beam energy, analysed observable • Large differences observed between lists reflect uncertainties in current understanding of hadron showers Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 10

Longitudinal shower profile - data and MC • Differential longitudinal profiles, 0 mm <= r < 60 mm from shower start • Shower core, reflect the e.m. shower information Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 11

Longitudinal shower profile - data and MC • Differential longitudinal profiles, 120 mm <= r < 180 mm from shower start • Larger radius range , reflect the neutron information Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 12

Transverse shower profile - data and MC Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 13

Transverse shower profile - data and MC • Important shower property for particle flow performance • Agreement between data and simulations around 20% • Most of the time, simulations above data in the shower core but below in the tails • Transverse profiles are not accurately simulated for electrons ➥ Some of the disagreement for hadrons may be due to instrumental effects Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 14

Transverse shower containment )&*+,- #$/#"(01$(% 456789:;< • Integrated lateral energy fraction • Core and tails well reproduced by QGSP_BERT Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 15

Mean shower radius !" • Shower radius: distance between hit and shower axis weighted with energy • Mean value and event-to- event fluctuations well described • Proper treatment of neutrons in shower evolution and detector response critical Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 16

Mean shower radius CALICE preliminary � , CERN 2007 � 100 Mean shower radius [mm] Data • 95 Shower radius: distance between LHEP QGSP_BERT 90 hit and shower axis weighted QGSP_FTFP_BERT 85 80 with energy 75 • 70 Showers become narrow with 65 increasing energy 60 55 50 10 20 30 40 50 60 70 80 Beam energy [GeV] CALICE preliminary CALICE preliminary � � , CERN 2007 , CERN 2007 � � 100 100 Mean shower radius [mm] Mean shower radius [mm] Data Data QGSC_QGSC 95 95 FTFP_BERT QGSC_CHIPS FTFP_BERT_TRV 90 90 QGSC_BERT FTF_BIC QGSC_BIC 85 85 80 80 75 75 70 70 65 65 60 60 55 55 50 50 10 20 30 40 50 60 70 80 10 20 30 40 50 60 70 80 Beam energy [GeV] Beam energy [GeV] Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 17

Leakage • mean energy [GeV] Leakage: shower start dependent energy and resolution 20 • CALICE preliminary The later the shower starts the more likely leakage is 10 • 20 GeV data 10 GeV data Reconstructed energy decreases 20 GeV LHEP 10 GeV LHEP 20 GeV QGSP_BERT 10 GeV QGSP_BERT and resolution worsens 0 0 0.5 1 1.5 2 2.5 3 3.5 4 shower start [ ] � energy sigma [%] energy sigma [%] - - 20 GeV 20 GeV � � simulation simulation 40 data data 40 QGSP_BERT LHEP 30 CALICE preliminary CALICE preliminary 20 20 0 0.5 1 1.5 2 2.5 3 3.5 4 0 0.5 1 1.5 2 2.5 3 3.5 4 shower start [ ] � shower start [ ] � Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 18

Summary • CALICE had very successful test-beams • Detector understanding is steadily increasing • The SiPM technology has proven to be robust and stable • The calibration is well under control • The performance is as expected and understood • ➥ strong support for predicted PFLOW performance • Promising measurement of shower shapes • improved sensitivity due to shower start • high granularity allows very detailed studies • agreement between simulations and data is around 20% • Analysis on going: stay tuned, more to come from CALICE Comparison of hadron shower data with simulations Shaojun Lu LCWS10, March 24-30, 2010 19