Overview of Geant4 Examples

2nd Finnish Geant4 Workshop

6-7 June 2005

Dennis Wright (SLAC)

Types of Examples

Novice

Simple: trivial detector with non-interacting particles

Detailed: complex detector with full physics

Extended

Testing and validation

Demonstrating Geant4 tools

Extending Geant4

Advanced

Practical applications

Examples from outside HEP (space, medical, etc)

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Novice Example N01

Fixed geometry: Ar gas mother volume with Al cylinder and Pb block with Al slices

Incident particle is a geantino – no physics interactions

No magnetic field and only the transportation process is enabled

Hard coded batch job and verbosity

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Novice Example N02

Pb target, Xe gas chambers (parameterized volumes)

All EM processes + decay included for , charged leptons and charged hadrons

Detector response

Trajectories and chamber hit collections may be stored

Visualization of detector and event

Command interface introduced

Can change target, chamber materials, magnetic field, incident particle type, momentum, etc. at run time

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Novice Example N03

Sampling calorimeter with layers of Pb absorber and liquid Ar detection gaps (replicas)

Exhaustive material definitions

Command interface

Randomization of incident beam

All EM processes + decay, with separate production cuts for , e+, e- (use for shower studies)

Detector response: E deposit, track length in absorber and gap

Visualization tutorial

Random number seed handling

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Novice Example N04

Simplified collider detector

all kinds of volume definitions

Magnetic field

PYTHIA primary event generator

Higgs decay by Z0, lepton pairs

Full set of EM + hadronic processes

Should use updated hadronic physics lists

Event filtering by using stacking mechanism

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Novice Example N05

Fast simulation with parameterized showers

EM showers (derived from G4VFastSimulationModel)

Pion showers (for illustration only – not used)

EM physics only

Use of G4FastSimulationManagerProcess

Simplified collider detector geometry

Drift chamber

EM, hadronic calorimeter

Ghost volume

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Novice Example N06

Water Cerenkov detector with air “bubble”

Materials

Specification of optical properties

Specification of scintillation spectra

Physics

Optical processes

Generation of Cerenkov radiation, energy loss collected to produce scintillation

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Novice Example N07

3 simplified sandwich calorimeters (Pb, Al, Ar)

Run-based (as opposed to event-based) hit accumulation

Changing geometries without re-building world

Setting different secondary production cuts for each calorimeter using G4Region

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Extended Examples

Testing and validation of processes and tracking

Electromagnetic (TestEm1 – TestEm10)

Field (field01 – field03)

Geometry (olap)

Demonstration of Geant4 tools

Analysis (A01) ,event generator, g3tog4, persistency

Biasing (B01-B03), optical, run and event

Extensions of Geant4

GDML

Medical (DICOM files)

Parallel computing (ParN02, ParN04)

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Advanced Examples

HEP detectors

CMS hadron calorimeter test beam

ATLAS Forward Liquid Ar Calorimeter

LHCb Rich test beam

Neutron Shielding

Medical (brachytherapy)

Space applications

Gamma ray telescope

X-ray telescope

X-ray fluorescence

Underground physics (liquid Xe dark matter detector)

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GDML Example

Identical to example N03 (sampling calorimeter), except

GDML used for geometry description

GDML schema supports:

Numerical expressions, constants, rotations, translations, units

Materials

CSG + boolean solids

Geometrical structure (volumes, placements)

Uses Xerxes-C XML parser (linux only)

Installation instructions included in example

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Brachytherapy Example

Physics

Low energy EM processes for e-, 

Standard EM for e+

Sensitive detector

“phantom” consisting of soft tissue

Analysis

Energy deposition stored in n-tuple

Store primary particle energy spectra

1D, 2D histograms of energy deposition

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Gamma Ray Space Telescope

Use of messengers to change geometry interactively

Modular physics list

Particle generator with monochromatic or power law spectrum

Readout geometry of Si tracker strips

Hits collection stored in ascii file

Simple digitization using hits collection to produce digi collections

.

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X-ray Telescope (1)

Simple model of x-ray telescope to study proton damage

Geometry:

single shell nickel-gold mirror

two cones for paraboloid, two for hyperboloid sections

aluminum baffle

main telescope: carbon fiber tube, aluminum end caps

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X-ray Telescope (2)

Main physics process is multiple scattering of protons from mirror surfaces

also e+, e-, gamma physics processes

General particle source

many methods available to customize event generation

Visualization of proton tracks

AIDA interface for analysis

energy distribution histograms of protons reaching detector

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Underground Physics

Realistic example of underground dark matter search experiment

Detailed geometry, including optional file describing laboratory

Physics

Low energy, standard EM

Optical processes

Radioactive decay

General particle source

Many macro files for various run conditions

.

Mirror

Xe gas

Xe liquid

Grids

PMT

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Summary

7 novice examples

Users’ Guide for Application Developers, Chapter 9.1

Code in geant4/examples/novice

Many extended examples

Users' Guide for Application Developers, Chapter 9.2

Code in geant4/examples/extended

15 advanced examples

Users’ Guide for Application Developers, Chapter 9.3

Code in geant4/examples/advanced

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Web Presentation Improvement

2005-05-14T14:38:24