Low Energy Electromagnetic Physics

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Low Energy Electromagnetic Physics

• Maria Grazia Pia, INFN Genova
• on behalf of the LowE WG

http//www.ge.infn.it/geant4/lowE/index.html
Geant4 Workshop and Geant4 D Review, CERN,
October 2002
2
The process in a nutshell

• We have and maintain a URD
• Regular contacts with users
• We have a process for requirements management
• But we would like to have a tool for it!
• We do analysis and design
• We validate our designs against use cases
• We do design and code reviews
• not enough, however
• main problem geographical spread
• Unit, package integration, system tests
  validation
• we do a lot but we would like to do more
• Limited by availability of resources for core
  testing
• Need a more systematic approach and better tools?
  Test Analysis Project
• Close collaboration with users

• Full requirements traceability
• Still improving it added documentation and
  validation results as traceability items
• in progress traceability documentation from
  simple matrix to Rose model
• We regularly hold WG meetings to discuss and
  agree together our project planning
• We keep everything in CVS
• Code, designs, tests, documents, papers etc.
• We have a SPI process
• With some spells of SPD sometimes
• Collaboration with Anaphe for a common (tailored)
  process
• We maintain a web site
• LowE, advanced examples, WG projects

More details see talk on Software Process in
Physics, Geant4 Review 2001
3
Recent physics activities

• Electron processes
• New parameterisations of LLNL data
• Various bug fixes
• Tests against NIST database (range)
• Tests against Sandia database
• Photon processes
• Rather stable
• Tests of angular distributions in progress
• Polarisation
• Improvement of Compton
• g conversion in progress
• Contacts with experiments for common validation
  tests

• Auger effect
• New
• Fluorescence
• Small fixes and improvements while
  re-implementing in design iteration
• Test beam validation in collaboration with ESA
  Science Payload Division
• PIXE
• Toy model
• Established contacts for databases, plans for new
  model
• Protons, ions
• Stable, minor improvements
• Bragg peak tests in progress
• Antiprotons
• Paper in progress, very close to submission

4
Photons mass attenuation coefficient
UR 1.1
Fe
Comparison against NIST data
Tests by IST - Natl. Inst. for Cancer Research,
Genova (F. Foppiano et al.)
LowE accuracy 1
Also water, Pb
This test will be introduced into the Test
Analysis project for a systematic verification
5
Photon attenuation Geant4 vs. NIST data
Test and validation by IST - Natl. Inst. for
Cancer Research, Genova
UR 1.1
Pb
water
Fe

• ? Low Energy EM
• Standard EM
• w.r.t. NIST data

accuracy within 1
6
Photons angular distributions
UR 1.1
Rayleigh scattering Geant4-LowE and expected
distribution (more work in progress)
7
Photons, evidence of shell effects
UR 1.1
Photon transmission, 1 mm Pb
Photon transmission, 1 mm Al
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Electron Bremsstrahlung
UR 1.1

• New parameterisations of EEDL data library
• in response to problem reports from various users
• precision is now 1.5
• Plans
• Systematic verification over Z and energy
• Need Test Analysis Project for automated
  verification

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Electron ionisation
UR 1.1

• New parameterisations of EEDL data library
• in response to problem reports from various users
• precision is now better than 5 for 50 of
  the shells, poorer for the 50 left
• Plans
• Systematic verification over shell, Z and energy
• Need Test Analysis Project for automated
  verification (all shells, 99 elements!)

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Electrons range
UR 1.1
Al
Range in various simple and composite
materials Compared to NIST database
Also Be, Fe, Au, Pb, Ur, air, water, bone,
muscle, soft tissue
Testbed for TestAnalysis prototype
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Electrons dE/dx
UR 1.1
Ionisation energy loss in various
materials Compared to Sandia database More
systematic verification planned (for publication)
Also Fe, Ur
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Electrons, transmitted
UR 1.1
20 keV electrons, 0.32 and 1.04 mm Al
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Protons
UR 2.1
UR 2.5
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Antiprotons
UR 2.3

• Dashed
• Geant4 LowE proton
• Solid
• Geant4 LowE Quantal Harmonic Oscillator model
• Dotted-dashed
• Non-linear calculation by Arista and Lifschitz
• Points
• Experimental data from ASACUSA

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Ions
UR 2.2
Ar and C ions
Deuterons
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Polarisation
Cross section

• Integrating over ?
• Sample ?
• ? - Energy Relation ? Energy
• Sample of ? from P(?) a (b c cos2 ?)
  distribution

Sample Methods
Low Energy Polarised Compton
250 eV -100 GeV
UR 4.1, D.1
Scattered Photon Polarization
More details talk on Geant4 Low
Energy Electromagnetic Physics

• ? Polar angle
• ? Azimuthal angle
• ? Polarization vector

Other polarised processes under development
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Fluorescence
UR 3.1
Experimental validation test beam data, in
collaboration with ESA Science Payload Division
Microscopic validation against reference data
Spectrum from a Mars-simulant rock sample
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Auger effect
UR 3.1
New process, validation in progress
Auger electron emission from various materials
Sn, 3 keV photon beam, electron lines w.r.t.
published experimental results
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Contribution from users

• Many valuable contributions to the validation of
  LowE physics from users all over the world
• excellent relationship with our user community
• User comparisons with data usually involve the
  effect of several physics processes of the LowE
  package
• A small sample in the next slides
• no time to show all!

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GEANT4 Workshop, 2002 30 September 4 October
GEANT4 Medical Applications at LIP

• P. Rodrigues, A. Trindade, L.Peralta, J. Varela

LIP Lisbon
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Homogeneous Phantom
P. Rodrigues, A. Trindade, L.Peralta, J. Varela,
LIP

• Simulation of photon beams produced by a Siemens
  Mevatron KD2 clinical linear accelerator
• Phase-space distributions interface with GEANT4
• Validation against experimental data depth dose
  and profile curves

LIP Lisbon
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Electron Transport at Low Energies

• Evaluation of electron range for different GEANT4
  releases

GEANT4 (LowStd)
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Dose Calculations with 12C

• Bragg peak localization calculated with GEANT4
  (stopping powers from ICRU49 and Ziegler85) and
  GEANT3 in a water phantom
• Comparison with GSI data

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Geant4 low energy validation
Jean-Francois Carrier, Louis Archambault, Rene
Roy and Luc Beaulieu Service de radio-oncologie,
Hotel-Dieu de Quebec, Quebec, Canada Departement
de physique, Universite Laval, Quebec, Canada
The following results will be published soon.
They are part of a general Geant4 low energy
validation project.
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• Using Geant4, we calculated depth-dose curves
  for many different electron or photon sources
• Beams
• monoenergetic beam
• realistic clinical accelerator beam
• Point sources
• monoenergetic source
• source with real nuclide energy spectra
• and different irradiated media
• Homogeneous
• water, Be, Mo or U
• Heterogeneous
• water/Al/lung/water
• water/air/steel/air/water

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Uranium irradiated by electron beam
Fig 1. Depth-dose curve for a semi-infinite
uranium slab irradiated by a 0.5 MeV broad
parallel electron beam
1Chibani O and Li X A, Med. Phys. 29 (5), May 2002
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Multi-slab medium irradiated by photons
Fig 2. Depth-dose curve for a multi-slab medium
irradiated by a 18 MV realistic clinical
accelerator photon beam
2Rogers D W O and Mohan R,http//www.irs.inms.nrc.
ca/inms/irs/papers/iccr00/iccr00.html
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Water phantom irradiated by clinac beam
Fig 3. Relative dose distribution for a water
phantom irradiated by a 6 MeV Clinac 2100C
electron beam
3Ding G X and Rogers D W O http//gold.sao.nrc.ca/
inms/papers/PIRS439/pirs439.html
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Ions

• Independent validation at Univ. of Linz (H. Paul
  et al.)
• Geant4-LowE reproduces the right side of the
  distribution precisely, but about 10-20
  discrepancy is observed at lower energies

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Dose distribution TG 43 protocol, experimental
data (S. Paolo Hospital, Savona), G4-LowE
S. Guatellis thesis
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Application
and more!
Not only space and medical!
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Team work!
Geant4 Low Energy Electromagnetic Working
Group users all over the world

• Students
• Jean-Francois Carrier
• Stephane Chauvie
• Elena Guardincerri
• Susanna Guatelli
• Alfonso Mantero
• Pedro Rodrigues
• Andreia Trindade
• Matteo Tropeano

The validation plots in this presentation have
been contributed by 19 people from 9
countries Argentina, Austria, Canada, Italy,
Portugal, Russia, Spain, Switzerland, UK
Thanks to all!
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Further physics improvements and extensions

• Various projects in progress
• all motivated by requirements in the URD
• Some examples in the following slides
• no time to show all!

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Bremsstrahlung Models
UR A.5

• Current bremstrahlung polar angle generation
  scheme is independent of both atomic number, Z,
  and emitted photon momentum, k
• Does not account variations due to the screening
  of the nucleus by the atomic electrons
• At generator level, for 50 keV incident electrons
  with k/T0.7 in Ag

New model (2BN) to be implemented by LIP group
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Polarisation
theory
UR 1.4, 4.1
simulation
Polarisation of a non-polarised photon beam,
simulation and theory
Ratio between intensity with perpendicular and
parallel polarisation vector w.r.t. scattering
plane, linearly polarised photons
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Ongoing significant effort in OOAD
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Other activities in the WG

• Advanced examples
• Simulation analysis in a distributed computing
  environment
• Test Analysis
• Technology transfer
• Training

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Technology transfer
Particle physics software aids space and
medicine M.G. Pia and J. Knobloch

Geant4 is a showcase example of technology
transfer from particle physics to other fields
such as space and medical science . CERN
Courier, June 2002
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Talksin WG web

1. The Geant4 Toolkit simulation capabilities and
   application results   M.G. Pia et al., 8th
   Topical Seminar on Innovative Particle and
   Radiation Detectors, Siena, 2002
2. Geant4 a powerful tool for medical physics   E.
   Lamanna et al., 8th Topical Seminar on Innovative
   Particle and Radiation Detectors, Siena, 2002
3. Dose calculation for radiotherapic treatment on a
   distributed computing environment   S. Chauvie
   et al., 8th Topical Seminar on Innovative
   Particle and Radiation Detectors, Siena, 2002
4. Parallel Geant4 simulation in medical and space
   science applications   J. Moscicki et al., 8th
   Topical Seminar on Innovative Particle and
   Radiation Detectors, Siena, 2002
5. Simulation and analysis for astroparticle
   experiments   A. Howard et al., 8th Topical
   Seminar on Innovative Particle and Radiation
   Detectors, Siena, 2002
6. Leipzig applicators Montecarlo simulations
   results and comparison with experimental and
   manufacturer's data   M. Tropeano et al., 21st
   ESTRO Meeting, Prague, 2002
7. Tools for simulation and analysis   A. Pfeiffer
   and M.G. Pia (for the Geant4 and Anaphe
   Collaborations), ICHEP02, Amsterdam, 2002
8. The Geant4 Simulation Toolkit and Its Low Energy
   Electromagnetic Physics Package   S. Chauvie et
   al., 44th Annual Meeting of the American Ass. of
   Physicists in Medicine, Montreal, 2002
9. The Geant4 Toolkit Overview   M. G. Pia,
   Invited lecture at the MCNEG Workshop,
   Stoke-on-Trent, UK, 2002
10. Medical applications of the Geant4 Simulation
    Toolkit   M. G. Pia, Invited lecture at the
    MCNEG Workshop, Stoke-on-Trent, UK, 2002
11. Simulation software applications and results in
    the bio-medical domain   M. G. Pia et al., VII
    International Conference on Advanced Technologies
    and Particle Physics, Como, 2001
12. From HEP computing to bio-medical research and
    vice-versa technology transfer and application
    results   M. G. Pia et al., Plenary talk at CHEP
    2001, Beijing, China, 2001
13. Architecture of Collaborating Frameworks  
    A.Pfeiffer et al., CHEP2001, Beijing, China, 2001
14. Simulation For Astroparticle Experiments And
    Planetary Explorations   A.Brunengo (for the
    Geant4 Low Energy Electromagnetic Group),
    CHEP2001, Beijing, China, 2001
15. Geant4 Low Energy Electromagnetic Physics   M.
    G. Pia (for the Geant4 Low Energy Electromagnetic
    Group), CHEP2001, Beijing, China, 2001
16. The GEANT4 simulation toolkit   G. Santin, Monte
    Carlo Workshop for Nuclear Medicine applications,
    July 2001
17. Geant4 simulation capabilities and application
    results   M.G. Pia (for the Geant4
    Collaboration), EPS-HEP Conference, Budapest,
    July 2001

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Resources
Status on 1 September 2002

• New collaborators
• Pablo Cirrone (INFN-LNS)
• Luis Peralta, Pedro Rodrigues, Andreia Trindade
  (LIP, Lisbon)
• Group from INFN-Gran Sasso also interested to join

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Conclusions

• We do a lot of work
• and we do our best to do it well
• a rigorous software process, continuous SPI
• very effective team-work, several brilliant and
  motivated young collaborators
• We have plenty of interesting physics results in
  a new (and difficult) simulation domain
• significant progress in the last year in a few
  problematic areas
• dont forget in what status we inherited the
  package, when the WG was created!
• A huge user community worldwide
• excellent, constructive relationship between
  users and developers
• more support for our activities outside the
  Collaboration than inside???
• Many new projects in the WG, not only physics
• Testing system, analysis, advanced examples,
  distributed computing, technology transfer
• More information in http//www.ge.infn.it/geant4/l
  owE/index.html