1. Low Energy Electromagnetic Physics
Maria Grazia Pia, INFN Genova
on behalf of the LowE WG
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 (acceptance)
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
Ample 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 (GDPM approach)
We have a SPI process
With some spells of SPD sometimes…
Collaboration with Anaphe for a common (tailored) process
We keep everything in CVS
(not in our head…)
Code, designs, tests, documents etc.
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 a 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

8. 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

9. 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!)

10. 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 Test&Analysis prototype

11. 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

12. Electrons, transmitted
UR 1.1
20 keV electrons, 0.32 and 1.04 mm Al

13. Nuclear stopping power
Protons
Stopping power
Z dependence for various energies
Ziegler and ICRU models
UR 2.1
Ziegler and ICRU, Fe
Ziegler and ICRU, Si
Nuclear stopping power
Straggling
Bragg peak (with hadronic interactions)
UR 2.5

14. Antiprotons UR 2.3 New: comparison with another theoretical model
Non-linear calculation by Arista and Lifschitz
Dashed
Geant4 LowE proton
Solid
Geant4 LowE Quantal Harmonic Oscillator model
Dotted-dashed
Calculation by Arista and Lifschitz
Points
Data from ASACUSA

15. Ions
UR 2.2
Ar and C ions
Deuterons

16. Scattered Photon Polarization
Polarisation
Cross section:
UR 4.1, D.1 y O z x q a f hn
hn0  A C
Scattered Photon Polarization
250 eV -100 GeV
 Polar angle
 Azimuthal angle
 Polarization vector
Low Energy
Polarised Compton
10 MeV
small 
large 
100 keV
1 MeV
More details: talk on Geant4 Low Energy Electromagnetic Physics
Other polarised processes under development

17. Fluorescence UR 3.1 Experimental validation:
test beam data, in collaboration with ESA Science Payload Division
Microscopic validation: against reference data
Scattered
photons
Fe lines
GaAs lines
Spectrum from a Mars-simulant rock sample

18. 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

19. 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!

20. P. Rodrigues, A. Trindade, L.Peralta, J. Varela
GEANT4 Workshop, 2002
30 September – 4 October
GEANT4 Medical Applications at LIP
P. Rodrigues, A. Trindade, L.Peralta, J. Varela
LIP – Lisbon

21. P. Rodrigues, A. Trindade, L.Peralta, J. Varela, LIP
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
15x15 cm2
Differences
10x10 cm2
Differences
15x15 cm2
10x10 cm2
LIP – Lisbon

22. P. Rodrigues, A. Trindade, L.Peralta, J. Varela, LIP
Electron Transport at Low Energies
P. Rodrigues, A. Trindade, L.Peralta, J. Varela, LIP
Evaluation of electron range for different GEANT4 releases
GEANT4 (Low+Std)
Styrophoam
Lead

23. P. Rodrigues, A. Trindade, L.Peralta, J. Varela, LIP
Dose Calculations with 12C
P. Rodrigues, A. Trindade, L.Peralta, J. Varela, LIP
Bragg peak localization calculated with GEANT4 (stopping powers from ICRU49 and Ziegler85) and GEANT3 in a water phantom
Comparison with GSI data

24. 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.

25. Jean-Francois Carrier, Louis Archambault, Rene Roy and Luc Beaulieu
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
Jean-Francois Carrier, Louis Archambault, Rene Roy and Luc Beaulieu

26. Uranium irradiated by electron beam
Jean-Francois Carrier, Louis Archambault, Rene Roy and Luc Beaulieu
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

27. Multi-slab medium irradiated by photons
Jean-Francois Carrier, Louis Archambault, Rene Roy and Luc Beaulieu
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,

28. Water phantom irradiated by clinac beam
Jean-Francois Carrier, Louis Archambault, Rene Roy and Luc Beaulieu
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

29. 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

30. Dose distribution: TG 43 protocol, experimental data (S
Dose distribution: TG 43 protocol, experimental data (S. Paolo Hospital, Savona), G4-LowE
 Protocol
 Data (SV)
 G4-LowE
S. Guatelli’s thesis

31. and more! Application Not only “space and medical”! Cosmic rays,
jovian electrons
Solar X-rays, e, p
Courtesy SOHO EIT
Application
and more!
Courtesy of S. Magni, Borexino
Not only
“space and medical”!

32. users all over the world
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
Thanks to all!

33. 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!

34. 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/T=0.7 in Ag
New model (2BN) to be implemented by LIP group

35. Polarisation of a non-polarised photon beam, simulation and theory
UR 1.4, 4.1
500 million events
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

36. Ongoing significant effort in OOAD

37. Other activities in the WG
Advanced examples
Simulation + analysis in a distributed computing environment
Test & Analysis
Technology transfer
Training

38. 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

39. Talks since last workshop in WG web
The Geant4 Toolkit: simulation capabilities and application results    M.G. Pia et al., 8th Topical Seminar on Innovative Particle and Radiation Detectors, Siena, 2002
Geant4: a powerful tool for medical physics    E. Lamanna et al., 8th Topical Seminar on Innovative Particle and Radiation Detectors, Siena, 2002
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
Parallel Geant4 simulation in medical and space science applications    J. Moscicki et al., 8th Topical Seminar on Innovative Particle and Radiation Detectors, Siena, 2002
Simulation and analysis for astroparticle experiments    A. Howard et al., 8th Topical Seminar on Innovative Particle and Radiation Detectors, Siena, 2002
Leipzig applicators Montecarlo simulations: results and comparison with experimental and manufacturer's data    M. Tropeano et al., 21st ESTRO Meeting, Prague, 2002
Tools for simulation and analysis    A. Pfeiffer and M.G. Pia (for the Geant4 and Anaphe Collaborations), ICHEP02, Amsterdam, 2002
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
The Geant4 Toolkit: Overview    M. G. Pia, Invited lecture at the MCNEG Workshop, Stoke-on-Trent, UK, 2002
Medical applications of the Geant4 Simulation Toolkit    M. G. Pia, Invited lecture at the MCNEG Workshop, Stoke-on-Trent, UK, 2002
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
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
Architecture of Collaborating Frameworks    A.Pfeiffer et al., CHEP2001, Beijing, China, 2001
Simulation For Astroparticle Experiments And Planetary Explorations    A.Brunengo (for the Geant4 Low Energy Electromagnetic Group), CHEP2001, Beijing, China, 2001
Geant4 Low Energy Electromagnetic Physics    M. G. Pia (for the Geant4 Low Energy Electromagnetic Group), CHEP2001, Beijing, China, 2001
The GEANT4 simulation toolkit    G. Santin, Monte Carlo Workshop for Nuclear Medicine applications, July 2001
Geant4: simulation capabilities and application results    M.G. Pia (for the Geant4 Collaboration), EPS-HEP Conference, Budapest, July 2001
Talks since last workshop in WG web

40. Training User-centric approach:
National School on Detector Technologies, Torino, Feb. 2002
Lectures + “Geant4 through an example”
Geant4 & Anaphe mini-workshop, Gran Sasso Lab, July 2002
Tutorials + “Geant4 through an example” +demo
Geant4 User Workshop, Salamanca, July 2002
Lectures + exercises
Geant4 & Anaphe mini-workshop, INFN-LNS Lab, November 2002
Tutorials + + “Geant4 through an example” +demo “Geant4 through an example” +demo
User-centric approach:
Introduction to “advanced” software engineering concepts
Complete (from the user’s view) training: simulation + analysis

41. Resources Status on 1 September 2002 New collaborators:
Pablo Cirrone (INFN-LNS)
Luis Peralta, Pedro Rodrigues, Andreia Trindade (LIP, Lisbon)
Interest expressed by small group at INFN-Gran Sasso Lab

42. More information in http://www.ge.infn.it/geant4/lowE
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
don’t 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 projects in the WG, not only physics
Testing system, analysis, advanced examples, general electromagnetic OOAD, distributed computing, technology transfer
More information in
Conclusions