Geant4 “Standard” Geant4 “Standard” Electromagnetic Electromagnetic Physics PackagePhysics Package

Geant4 Standard EM groupGeant4 Standard EM groupMC 2005MC 2005

Chattanooga, Tennessee, USAChattanooga, Tennessee, USA17-21 April 2005 17-21 April 2005

M. Maire, MC'2005 G4 Standard EM 2

Geant4 Standard EM groupGeant4 Standard EM group

H.Burkhardt, V.M.Grichine, H.Burkhardt, V.M.Grichine, P.Gumplinger, V.N.Ivanchenko, P.Gumplinger, V.N.Ivanchenko, R.P.Kokoulin, M.Maire, L.UrbanR.P.Kokoulin, M.Maire, L.Urban

BINP, Novosibirsk, RussiaBINP, Novosibirsk, RussiaCERN, Geneva, SwitzerlandCERN, Geneva, Switzerland

ESA, Noordwijk, The NetherlandsESA, Noordwijk, The NetherlandsLAPP, Annecy, FranceLAPP, Annecy, FranceLPI, Moscow, RussiaLPI, Moscow, Russia

MEPhI, Moscow, RussiaMEPhI, Moscow, RussiaRMKI, Budapest, HungaryRMKI, Budapest, Hungary

TRIUMF, Vancouver, CanadaTRIUMF, Vancouver, Canada

M. Maire, MC'2005 G4 Standard EM 3

OutlineOutline

►Standard EM packageStandard EM package►Overview on major developments Overview on major developments

since 2003since 2003►Validation/comparisonsValidation/comparisons►EM PhysicsListsEM PhysicsLists►Acceptance suiteAcceptance suite►New developments New developments ►ConclusionsConclusions

M. Maire, MC'2005 G4 Standard EM 4

Standard EM packageStandard EM package

►Naturally continue Geant3 EM physics Naturally continue Geant3 EM physics ► Include a complete set of models for Include a complete set of models for

simulation of electromagnetic processes simulation of electromagnetic processes in the energy range from in the energy range from 1 keV to 10 1 keV to 10 PeVPeV

► Includes optical photons production and Includes optical photons production and transport transport

►Focus on HEP experiments, well Focus on HEP experiments, well applicable for instrumentation, space, applicable for instrumentation, space, and medicine studiesand medicine studies

M. Maire, MC'2005 G4 Standard EM 5

Design iteration in Standard EM Design iteration in Standard EM packagepackage

► Standard EM package was one of physics Standard EM package was one of physics package working from 1package working from 1stst Geant4 release Geant4 release

► Created using Geant3 expertiseCreated using Geant3 expertise► Used practically in all Geant4 applicationsUsed practically in all Geant4 applications

LHC experiments LHC experiments Space and medicine applicationsSpace and medicine applications

► Used in production for BaBar for many yearsUsed in production for BaBar for many years► Some architecture problems were accumulatedSome architecture problems were accumulated ► In 2003 the package were redesignedIn 2003 the package were redesigned► New developments were enabled New developments were enabled

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Major activities since 2003Major activities since 2003

► Physics improvements:Physics improvements: Evolutions of multiple scattering modelEvolutions of multiple scattering model Hadron ionization was updatedHadron ionization was updated New ion ionizationNew ion ionization Muon processes were updatedMuon processes were updated Updated cross section for Compton effect Updated cross section for Compton effect Revised PAI modelsRevised PAI models New high energy processesNew high energy processes

► Evolution in optical photons simulationEvolution in optical photons simulation► Cut per region from G4 5.1Cut per region from G4 5.1► Model design from G4 6.0Model design from G4 6.0

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Hadron/ion ionization (1)Hadron/ion ionization (1)

► Corrected Bethe-Bloch Corrected Bethe-Bloch formula for the Eformula for the Ekinkin>2 >2 MeVMeV

► ICRU49 parameterization ICRU49 parameterization is used for the Eis used for the Ekinkin< 2 MeV< 2 MeV

► Scaling relation for other Scaling relation for other hadrons/ionshadrons/ions

► Ion Ion effective chargeeffective charge is is recalculated at each step recalculated at each step of the particle and is used of the particle and is used also for tracking in EM also for tracking in EM fieldfield

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Hadron/ion ionization (2)Hadron/ion ionization (2)

►Review of corrections to the Bethe-Review of corrections to the Bethe-Bloch formulaBloch formula

► C – shell correction (C – shell correction (was asymptotic formulawas asymptotic formula)) G – Mott correction (G – Mott correction (newnew)) δδ – density correction – density correction F – finite size correction (F – finite size correction (newnew)) LL11- Barkas correction (- Barkas correction (newnew))

LL22- Bloch correction (- Bloch correction (newnew))

►New class G4EmCorrectionsNew class G4EmCorrections

2

21

max

2222

2

22

0 21

2

2ln4 LzzL

FG

Z

C

T

T

I

cmzrN

dx

dE cee

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Integral Integral approachapproach

► EM cross sections depend EM cross sections depend on energyon energy

► Precision of interaction Precision of interaction probability depends on probability depends on step size and energy step size and energy changechange

► Integral approach: Integral approach: interaction probability is interaction probability is sampled using integral sampled using integral method (MC’91 method (MC’91 Proceedings)Proceedings)

► Integral approach allows to Integral approach allows to have any step size for have any step size for ionizationionization

})(exp{ sE ii

inp

})(exp{ ndsEp

constant

integral

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Performance comparison Performance comparison 5.2/6.25.2/6.2

► Performance improved Performance improved after design iterationafter design iteration

► Initialization time Initialization time smaller by 2 times for smaller by 2 times for complecate geometry complecate geometry and much more for and much more for simple geometrysimple geometry

► Size of EM tables Size of EM tables smaller by 2 times or smaller by 2 times or more (HARP, CMS)more (HARP, CMS)

► CPU per event less at CPU per event less at least by 10%least by 10%

► Higher performance for Higher performance for low cutslow cuts

Intel 2.4GHz 512 KB

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Geant4/Penelope comparisonGeant4/Penelope comparison(End point of secondaries e-)(End point of secondaries e-)

1.25 MeV gamma in 1 mm Si

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HEP CalorimetryHEP Calorimetry

► G4 5.2p02 close to G3G4 5.2p02 close to G3► G4 6.2p02 include G4 6.2p02 include

integral methodintegral method► G4 7.0 include msc G4 7.0 include msc

modificationmodification► Integral methodIntegral method for for

tracking and updated tracking and updated model of multiple model of multiple scatteringscattering provide provide less cut dependent less cut dependent resultsresults

Average energy deposition in lAr

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Geant4 muon interactionsGeant4 muon interactions

► Basic processes:Basic processes: IonisationIonisation BremsstrahlungBremsstrahlung Production of eProduction of e++e-e- Muon-nuclear Muon-nuclear

interactionsinteractions

► Muon production Muon production and transport in and transport in Geant4 is available Geant4 is available up to 10 PeVup to 10 PeV

10-3 10-2 10-1 100

10-8

10-7

10-6

10-5

10-4

10-3

10-2

e+e-

h

Fe, 100 GeV

(

E, )

, cm

2 /

g

v = / E v = / E10-3 10-2 10-1 100

10-8

10-7

10-6

10-5

10-4

10-3

10-2

e+e-

h

Fe, 10000 GeV

Muon differential cross sections

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Verification theory/Geant4Verification theory/Geant4difference less than 5%difference less than 5%

-4 -3 -2 -1 0 1 2 3 4

100

101

102

103

104

105

106

107

No.

inte

ract

ions

per

bin

lg (, GeV)

Test of energy sampling.Lines: theoryPoints: Geant4 (v.6.2p01)

T = 10 TeV, 106 muons

CaCO3 , 5 m, cut 1 cm

brems

knock-on

nucl

pairs

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New High energy EM New High energy EM processesprocesses

► EM background due EM background due to high energy EM to high energy EM interaction with interaction with media: media:

► → → µµ++µµ-- ( (~Z~Z22))► ee++ µ µ++µµ- - ((~Z)~Z)► ee++ ++- - ((~Z)~Z)

► Visible at LEP and Visible at LEP and High at SLCHigh at SLC

► Of concern for linear Of concern for linear colliderscolliders

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Background for Background for linear colliderlinear collider

High energy e+, e-, and can produce µ+µ- pair

1010 e / bunch After collimator ~ 103 µ+µ-

Angles of muons250 GeV beam

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User supportUser support

► Physics Reference Manual : complete Physics Reference Manual : complete description of models/sampling methodsdescription of models/sampling methods

► Extended examples : PhysicsLists, user Extended examples : PhysicsLists, user actions, visualization, analysis toolsactions, visualization, analysis tools

► Standard group supportStandard group support► 12 extended/electromagnetic examples12 extended/electromagnetic examples► 1 extended/medical example1 extended/medical example► 1 extended/optical examples1 extended/optical examples► 3 novices3 novices

► Hyper News discussionsHyper News discussions

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Acceptance suite for Standard Acceptance suite for Standard EM packageEM package

► To insure stability of To insure stability of results with timeresults with time

► To control To control performanceperformance

► Is based on extended Is based on extended electromagnetic electromagnetic examples examples

► G4EmCalculator is an G4EmCalculator is an interface to dE/dx interface to dE/dx and cross sectionsand cross sections

► Control on summary Control on summary numbers:numbers: Average energy Average energy

depositiondeposition Shower shapeShower shape Scattering angles Scattering angles

► Tests on cross Tests on cross sections and dE/dx sections and dE/dx

► Comparison of Comparison of histograms (in histograms (in project)project)

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New developments and plans New developments and plans for Standard EM packagefor Standard EM package

► Predefined G4Elements and G4Materials Predefined G4Elements and G4Materials with parameters from the NIST data base with parameters from the NIST data base will be available in the release 7.1will be available in the release 7.1

► Gamma processes in model designGamma processes in model design► Comparisons/validationComparisons/validation► Long-term prospects:Long-term prospects:

► Physics model on level of theory/experiment for all Physics model on level of theory/experiment for all processesprocesses

► High energy extensionsHigh energy extensions► Further performance improvementFurther performance improvement► Complete automatic acceptance suiteComplete automatic acceptance suite

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ConclusionsConclusions

►Geant4 Standard EM package is used in Geant4 Standard EM package is used in production of Monte Carlo results for production of Monte Carlo results for many yearsmany years

►Recently the package has been Recently the package has been redesignedredesigned

►Physics was extended and improvedPhysics was extended and improved►Performance was improvedPerformance was improved►There are plans to extend energy range There are plans to extend energy range

of the Standard physics of the Standard physics