Maria Grazia Pia, CERN/IT and INFN Genova Electromagnetic Physics Maria Grazia Pia CERN/IT and INFN...

Maria Grazia Pia, CERN/IT and INFN Genova

Electromagnetic PhysicsElectromagnetic Physics

Maria Grazia PiaCERN/IT and INFN Genova

S. Chauvie, V. Grichine, P. Gumplinger, V. Ivanchenko, R. Kokoulin,

S. Magni, M. Maire, P. Nieminen, M.G. Pia, A. Rybin, L. Urbanon behalf of the Geant4 Collaboration

Budker Inst. of PhysicsIHEP ProtvinoMEPHI Moscow Pittsburg University

MC2000 ConferenceMC2000 Conference, Lisbon, 20-23 October 2000

http://www.cerninfo.cern.ch/asd/geant4/geant4.html


Borexinoat Gran Sasso Laboratory

HighlightsHighlights

Gamma-ray Large Area Space

Telescope

ATLAS at LHC, CERN

CMS at LHC, CERN

BaBar at SLAC

XMM

X-ray telescope

A wide domain of applications with A wide domain of applications with a large user community in many fieldsa large user community in many fields

HEP, astrophysics, nuclear physics, space sciences, medical physics, radiation studies etc.

A rigorous approach to software engineeringA rigorous approach to software engineering

Courtesy of L3Courtesy of the Italian Nat. Inst. for Cancer

Research

E (MeV)

Photon attenuation

An extensive set of physics processes and An extensive set of physics processes and models over a wide energy rangemodels over a wide energy range

High energy Low energy photons

GLAST


Geant4 is a simulation Toolkit designed for a variety of applications

It has been developed and is maintained by an international collaboration of > 100 scientists

RD44 Collaboration

Geant4 Collaboration

The code is publicly distributed from the WWW, together with ample documentation

1st production release: end 1998 2 new releases/year since then

It provides a complete set of tools for all the typical domains of simulation

geometry and materials tracking detector response run, event and track management PDG-compliant particle management visualisation user interface persistency physics processes

It is also complemented by specific modules for space science applications


Software Engineering

plays a fundamental role in Geant4

User Requirements• formally collected• systematically updated• PSS-05 standard

Software Process• spiral iterative approach• regular assessments and improvements• monitored following the ISO 15504 model

Quality Assurance• commercial tools• code inspections• automatic checks of coding guidelines• testing procedures at unit and integration level• dedicated testing team

Object Oriented methods• OOAD• use of CASE tools

• essential for distributed parallel development• contribute to the transparency of physics

Use of Standards • de jure and de facto

Domain decomposition

has led to a hierarchical structure of

sub-domains linked

by a uni-directional

flow of

dependencies

Geant4 architecture


Features of Geant4 Physics OOD allows to implement or modify any

physics process without changing other parts of the software

open to extension and evolutionopen to extension and evolution

Tracking Tracking is independent from the physics processes

The generation of the final statefinal state is independent from the access and use of cross sections

Transparent access via virtual functions to

cross sections (formulae, data sets etc.) models underlying physics processes

An abundant set of electromagneticelectromagnetic and hadronic hadronic physics processes

a variety of complementary and alternative physics modelsphysics models for most processes

Use of public evaluated databasesevaluated databases

No tracking cuts, only production production thresholdsthresholds

thresholds for producing secondaries are expressed in rangerange, universal for all media

converted into energy for each particle and material

The transparency of the physics implementation contributes to the validation of experimental physics results


multiple scattering Bremsstrahlung ionisation annihilation photoelectric effect Compton scattering Rayleigh effect conversion e+e- pair production synchrotron radiation transition radiation Cherenkov refraction reflection absorption scintillation fluorescence Auger (in progress)

Electromagnetic physics

Comparable to Geant3 already in the 1st release (1997)

High energy extensionsHigh energy extensions fundamental for LHC experiments, cosmic ray experiments etc.

Low energy extensionsLow energy extensions fundamental for space and medical applications, neutrino

experiments, antimatter spectroscopy etc.

Alternative models for the same physics processAlternative models for the same physics process

energy lossIt handles

electrons and positrons , X-ray and optical photons muons charged hadrons ions


OO design

Alternative models, obeying the same abstract interface, are provided for the same physics interaction

Class diagram of electromagnetic physics


Standard electromagnetic processes

PhotonsPhotons Compton scattering conversion photoelectric effect

Electrons and positronsElectrons and positrons Bremsstrahlung ionisation

continuous energy loss from Bremsstrahlung and ionisation

ray production positron annihilation synchrotron radiation

Charged hadronsCharged hadrons

Shower profile, 1 GeV e- in water

J&H Crannel - Phys. Rev. 184-2 August69

1 keV up to O(100 TeV)1 keV up to O(100 TeV)


Features of Standard e.m. processes Multiple scatteringMultiple scattering

new model computes mean free path length and

lateral displacement

New energy loss algorithmNew energy loss algorithm optimises the generation of rays near

boundaries

Variety of modelsVariety of models for ionisation and energy loss

including the PhotoAbsorption Interaction model

Differential and Integral approachDifferential and Integral approach for ionisation, Bremsstrahlung, positron

annihilation, energy loss and multiple scattering

Multiple scattering

6.56 MeV proton , 92.6 mm Si

J.Vincour and P.Bem Nucl.Instr.Meth. 148. (1978) 399


Ionisation energy loss distribution produced by pions, PAI modelPAI model

3 GeV/c in 1.5 cm Ar+CH4

5 GeV/c in 20.5 m Si

PPhoto hoto AAbsorption bsorption IIonisation onisation ModelModel

Ionisation energy loss produced by charged particles in thin layers of absorbers


Low energy extensions: e-,

Based on EPDL97, EEDL and EADL evaluated data libraries

cross sections sampling of the final state

Photoelectric effect Compton scattering Rayleigh scattering conversion Bremsstrahlung Ionisation Fluorescence

250 eV up to 100 GeV250 eV up to 100 GeV

Photon transmission on 1 m Al

http://www.ge.infn.it/geant4/lowE


Photon attenuation coefficientPhoton attenuation coefficient

Comparison with NIST data

Standard Standard electromagnetic package

and Low EnergyLow Energy extensions0.01 0.1 1 10

0.01

0.1

1

10

100

1000

Geant4 LowEn NIST

/

(cm

2 /g

) in

iron

Photon Energy (MeV)

Fe

0.01 0.1 1 10-16

-14

-12

-10

-8

-6

-4

-2

0

2

4

6

8

10

12

14

16

Delta = (NIST-G4EMStand) / NIST

Delta = (NIST-G4LowEn) / NIST

Del

ta (

%)

Photon Energy (MeV)

water water


Low energy extensions: hadrons and ions

E > 2 MeV Bethe-Bloch 1 keV < E < 2 MeV

parameterisations Ziegler 1977, 1985 ICRU 1993 corrections due to chemical formulae

of materials nuclear stopping power

E < 1 keV free electron gas model Barkas effect taken into account down

to 50 keV quantum harmonic oscillator model

Various models, depending on the energy range and chargeVarious models, depending on the energy range and charge


Muon processes

Validity range

1 keV up to 10 PeV scale1 keV up to 10 PeV scale simulation of ultra-high

energy and cosmic ray physics High energy extensions based

on theoretical models

Bremsstrahlung Ionisation and ray production e+e- Pair production


Processes for optical photons

Optical photon its wavelength is much greater than the typical atomic spacing

Production of optical photons in HEP detectors is mainly due to Cherenkov effect and scintillation

Processes in Geant4Processes in Geant4 in-flight absorption Rayleigh scattering medium-boundary interactions

(reflection, refraction) Track of a photon entering a light concentrator CTF-Borexino


Openness to evolutionFrom the Minutes of LCB (LHCC Computing Board) meeting on 21 October, 1997:

Geant4 physics keeps evolvingGeant4 physics keeps evolvingwith attention to UR

facilitated by the OO technologyLower energy extensions, new models for polarisation, new models for material dependence etc.

“It was noted that experiments have requirements for independent, alternative physics models. In Geant4 these models, differently from the concept of packages, allow the user to understand how the results are produced, and hence improve the physics validation. Geant4 is developed with a modular architecture and is the ideal framework where existing components are integrated and new models continue to be developed.”


User support

User Support is a key feature of Geant4User Support is a key feature of Geant4 Users (experiments, laboratories, institutes) are members of the

collaboration itself User RequirementsUser Requirements are formally collected and regularly updated Extensive documentationdocumentation available from the web (5 manuals)

A Geant4 Training ProgrammeTraining Programme in preparation User Support through a web interface for code-related problem reports User Support through human interface for consultancy, investigation of

anomalous results etc. A distributed modeldistributed model of User Support

a large number of experts performs the support on the domain of their competence

The close relationship with user communities and their feedback is very valuable to Geant4


Geant4 electromagnetic physics Working Groups M. Maire (LAPP) P. Nieminen (ESA) M.G. Pia (INFN Genova) S. Agostinelli - (IST Genova) P. Andreo (Karolinska Inst.) D. Belkic (Karolinska Inst.) A. Brahme (Karolinska Inst.) A. Carlsson (Karolinska Inst.) G. Cabras (INFN Udine) S. Chauvie (INFN Torino) G. Depaola (Univ. Cordova) R. Cirami (INFN Trieste) E. Daly (ESA) A. De Angelis (INFN Udine) G. Fedel (INFN Trieste) J.M. Fernandez Varea (Univ. Barcelona) S. Garelli (IST Genova) R. Giannitrapani (INFN Udine) V. Grichine (LPI Moscow) I. Gudowska (Karolinska Inst.) P. Gumplinger (TRIUMF)

V. Ivanchenko (Budker Institute ) R. Kokouline (MEPhI, Moscow) E. Lamanna (INFN Cosenza) S. Larsson (Karolinska Inst.) R. Lewensohn (Karolinska Inst.) B.K. Lind (Karolinska Inst.) J. Lof (Karolinska Inst.) F. Longo (INFN Trieste) B. De Lotto (INFN Udine) F. Marchetto (INFN Torino) E. Milotti (INFN Udine) R. Nartallo (ESA) G. Nicco (Univ. Torino) B. Nilsson (Karolinska Inst.) V. Rolando (Univ. Piemonte Orient.) A. Rybin (IHEP Protvino) G. Santin (INFN Trieste) U. Skoglund (Karolinska Inst.) A. Solano (INFN Torino) R. Svensson (Karolinska Inst.) N. Tilly (Karolinska Inst.) L. Urban (KFKI Budapest)

Standard Standard e.m. Physics

Low EnergyLow Energy e.m. Physics


Conclusions

Geant4 is a simulation Toolkit, providing advanced tools for all the domains of detector simulation

Its areas of application span diverse fields: HEP and nuclear physics, astrophysics and space sciences, medical physics, radiation studies etc.

Geant4 is characterized by a rigorous approach to software engineering

Geant4 electromagnetic physics covers a wide energy range of interactions of electrons and positrons, photons, muons, charged hadrons and ions

An abundant set of electromagnetic physics processes is available, often with a variety of complementary and alternative physics models

Low and high energy extensions have opened new domains of applications

Thanks to the OO technology, Geant4 is open to extension and evolution


Related presentationsat this conference

V. Grichine Fast Simulation of X-ray Transition Radiation in the Geant4 Toolkit

P. Nieminen Space applications of the Geant4 Toolkit

P. Arce et al. Multiple scattering in Geant4 S. Chauvie Medical applications of the Geant4 Toolkit

http://www.ge.infn.it/geant4/lowE

http://www.ge.infn.it/geant4/dna

http://www.cerninfo.cern.ch/asd/geant4/geant4.html

Maria Grazia Pia, CERN/IT and INFN Genova Electromagnetic Physics Maria Grazia Pia CERN/IT and INFN...

Documents

Transcript of Maria Grazia Pia, CERN/IT and INFN Genova Electromagnetic Physics Maria Grazia Pia CERN/IT and INFN...