Geant4 electromagnetic physics for the LHC and other HEP applications

Transcription

1 Geant4 electromagnetic physics for the LHC and other HEP applications Andreas Schälicke on behalf of the Geant4 EM Working Groups DESY, Zeuthen October 18th, CHEP 2010, Taipei, Taiwan A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

2 Outline Introduction Geant4 EM physics Infrastructure upgrades Software design CPU performance Validation framework Physics validation Bremsstrahlung & Pair production Updated Fluctuation model Backscattering of electrons Multiple scattering of muons & hadrons Energy deposition in thin Si layer LHC type calorimeter response Summary A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

3 Introduction Geant4 is a toolkit for the simulation of the passage of particles through matter. EM physics processes interactions of e ± and γ electromagnetic interactions of muons, hadrons and ions x-ray processes and processes with optical photons... Application area HEP, medical, space,... dedicated models exist for different use cases A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

4 Introduction Geant4 is a toolkit for the simulation of the passage of particles through matter. EM physics processes interactions of e ± and γ electromagnetic interactions of muons, hadrons and ions x-ray processes and processes with optical photons... Application area HEP, medical, space,... dedicated models exist for different use cases A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

5 Infrastructure upgrades Common software design by EM Standard and Low-Energy available since G4 version 9.3 use higher level tools (e.g. spline interpolation in physics tables) allows combination of different models for different energy regions in one process new components for physics lists (Builder) A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

6 Infrastructure upgrades Improvements in CPU performance G4 9.3 default energy interval 1 kev-10 TeV Number of bins reduced to 70 ( 20% memory saving) significant improvement of start-up time for application with many materials (e.g. LHC experiments) Revised converter of cut in range to production thresholds Revised of physics vector classes Cleaned up standard EM initialization Geant4 version amd 32-bit amd 64 bit G s 179 s G s 56 s A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

7 Physics validation - Framework Two stage test approach low-statistics test run regularly by STT high-statistics test run using LxBatch, etc. Procedure semi-automatic run of jobs results generated by scripts comparison plots available on the Web Data Testing code in C++ Geant4 reference version WWW Converter Production scripts Root analysis PHP / JSP publishing Data in internal formats Macro Geant4 results Comparision plots Store of Data and publishing of results A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

8 Physics validation - Framework PHP based Web interface: new JSP based system in development (collaboration with G4 hadronic WG) msc_test emulsion med_proton pairp.nist brems.eedl brems.lpm brems.compare zeus em2.egs4 toshito tileatlas test46 test44 test41 test37 si_detector nrcc lhcb hecatlas fanocavity2 fanocavity em5.tramu em5.muscat em5.mu_iron em5.bscat em5.berger_si brems.hansen04 em12.etran em11.sandia cmscal brems.slace146 atlasbar 1786 figures ( 334 tags in 32 tests ) 01/01/ /01/ /01/ /01/ A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

9 Physics validation - Bremsstrahlung & Pair production New relativistic bremsstrahlung model Bethe-Heitler formula with corrections complete screening (valid E > 1 GeV) includes density and LPM effect and consistent combination a la Ter-Mikaelian available since Geant4 version 9.2 New relativistic pair production model includes LPM effect important only for E > 1 10 TeV available since Geant4 version 9.3

10 Physics validation - Multiple scattering & Fluctuation revised Urban multiple scattering model Update of the fluctuation model better description esp. for low Z materials available since G4 9.3 will be default in G4 9.4 new fluctuation model fixes unphysical behavior for low density materials results become less cut dependent included in G4 9.4 Energy loss of 500 MeV e- in 15 mm Ar+10% CO2 gas mixture 10 5 G4 9.3 new Model energy loss of primary (if not absorbed) (kev) L. Urban G4AI GEANT4 Workshop, ESA/ESTEC Noordwijk 4-8 Octob A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

11 Physics validation - Multiple scattering Backscattering of electrons new test for electron MSC energy MeV targets: Be, C, Al, Ti, Mo Urban MSC model with improved parameters gives good results Data: Lockwood et al., SANDIA Report SAND (1984). A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

12 Physics validation - Multiple scattering Backscattering of electrons new test for electron MSC energy MeV targets: Be, C, Al, Ti, Mo Urban MSC model with improved parameters gives good results Data: Lockwood et al., SANDIA Report SAND (1984). A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

13 Physics validation - Multiple scattering Multiple scattering of muons 7.3 Gev/c muon on Copper default model (Urban) gives good description of core deviation at large angles Data: S.A. Akimenko et al., NIM A 234, 518 (1986) A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

14 Physics validation - Multiple scattering Multiple scattering of muons 7.3 Gev/c muon on Copper default model (Urban) gives good description of core deviation at large angles new model (WentzelVI) even better will be default for muons in G4 9.4 Data: S.A. Akimenko et al., NIM A 234, 518 (1986) A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

15 Physics validation - Multiple scattering Multiple scattering of hadrons GeV/c various targets from Hydrogen to Lead comparison with data and Moliere theory Data: G. Shen et al., Phys.Rev.D 20, 1584 (1979) A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

16 Physics validation - Multiple scattering Multiple scattering of hadrons GeV/c various targets from Hydrogen to Lead comparison with data and Moliere theory Data: G. Shen et al., Phys.Rev.D 20, 1584 (1979) A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

17 Energy Deposit Spectrum : Thin Detector Physics validation - Fluctuation model energy deposition spectrum characterized by Most Probable energy deposition Full Width at Half Maximum Thin Silicon layer of : 300 um (Hancock), 1565 um (Nagata) Δ w w : Full Width at Half Maximum Δ : Most Probable Energy Deposition G4 9.4 Data: H. Bichsel, Rev.Mod.Phys. 60, 663 (1988) A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

18 Energy Deposit Spectrum : Thin Detector Physics validation - Fluctuation model energy deposition spectrum characterized by Most Probable energy deposition Full Width at Half Maximum Thin Silicon layer of : 300 um (Hancock), 1565 um (Nagata) Δ w w : Full Width at Half Maximum Δ : Most Probable Energy Deposition G4 9.3 Data: H. Bichsel, Rev.Mod.Phys. 60, 663 (1988) A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

19 Energy Deposit Spectrum : Thin Detector Physics validation - Fluctuation model energy deposition spectrum characterized by Most Probable energy deposition Full Width at Half Maximum Thin Silicon layer of : 300 um (Hancock), 1565 um (Nagata) Δ w w : Full Width at Half Maximum Δ : Most Probable Energy Deposition G4 9.4 Data: H. Bichsel, Rev.Mod.Phys. 60, 663 (1988) A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

20 Energy Deposit Spectrum : Thin Detector Physics validation - Fluctuation model energy deposition spectrum characterized by Most Probable energy deposition Full Width at Half Maximum Thin Silicon layer of : 300 um (Hancock), 1565 um (Nagata) Δ w w : Full Width at Half Maximum Δ : Most Probable Energy Deposition G4 9.3 Data: H. Bichsel, Rev.Mod.Phys. 60, 663 (1988) A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

21 Energy Deposit Spectrum : Thin Detector Physics validation - Fluctuation model energy deposition spectrum characterized by Most Probable energy deposition Full Width at Half Maximum Thin Silicon layer of : 300 um (Hancock), 1565 um (Nagata) Δ w w : Full Width at Half Maximum Δ : Most Probable Energy Deposition G4 9.4 Data: H. Bichsel, Rev.Mod.Phys. 60, 663 (1988) A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

22 Physics validation - LHC type calorimeter response Sampling Calorimeter Example Atlas EM calo simplified setup 2.3 mm Pb, 5.7 mm lar test visible energy fraction and resolution in general results very stable G4 version 9.4 gives 0.5% increased response relative resolution not changed A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15

23 Summary EM performance and infrastructure improvements common design with low energy processes new physics builder cover wider energy range by using different models in different energy regions sizable CPU performance increase during initialization stage EM physics improvements LPM effect consistent in Bremsstrahlung and Pair production revised fluctuation and MSC models extended validation suite with tests of MSC of electrons, muons and hadrons visible impact of LHC calorimeter response validation results accessible via new Web interface A. Schälicke (DESY, Zeuthen) Geant4 EM physics October 16, / 15