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Achievements of the LowE e.m. WG. Petteri Nieminen & Maria Grazia Pia. Geant4 Workshop Paris, 16-20 October 2000 Birth and growth of the Low Energy e.m. Physics WG. We applied for the creation of a new LowE e.m. WG in March 2000

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Achievements of the lowe e m wg

Achievements of the LowE e.m. WG

Petteri Nieminen &Maria Grazia Pia

Geant4 Workshop

Paris, 16-20 October 2000

Birth and growth of the low energy e m physics wg
Birth and growthof the Low Energy e.m. Physics WG

  • We applied for the creation of a new LowE e.m. WG in March 2000

  • WG created by the CB in April 2000

  • 9 members at the time of the creation

    • 3 of the initial members lost

    • including holder of full time contract

  • 33 members now

  • 3 new applications to be examined this week by CB/TSB

  • 3 new affiliations of existing collaborators

  • Contacts in progress with 3 new groups interested to join

How we work
How we work

Goal-directed project management

Spiral cyclic software process

Characterized by

  • Promotion of cross-WG activities

  • Close relationship with user communities

  • Regular Working Group meetings

  • Emphasis on training of all group members

  • Active strategy of talks and publications

    • for promotion of Geant4 and our own products

    • as an incentive and reward for the group members



Wide spectrum of development:


LowE e.m. Milestone Document, TSB April 2000

  • Assessment of the physics implementation

  • Physics updates and extensions

  • Software quality and software process improvement

  • Testing

  • Design improvement

  • Documentation and promotion


Thorough assessment of the existing software



physics performance

testing tools

Comparisons with experimental data

Comparisons with Standard e.m. processes in common validity range for debugging purpose

bugs and problems found and corrected

both in LowE and Standard...


  • Application to microdosimetry and nanodosimetry

Close collaboration with user groups in the assessment

New physics
New physics

  • New model for positive charged hadrons (Ziegler 1985)

  • Improvements on straggling (hadrons and ions)

  • Introduction of a dynamic dependence on effective charge into the range calculation

  • Improvements in the validity range of d ray production

  • New models for ion energy loss fluctuations

  • New model for negative charged hadrons

    • first model was limited to a set of materials

    • then extended to all elements, based on theoretical calculations

  • OO Analysis started for positrons

Results photons
Results, photons




Plans for extensions
Plans for extensions

  • Foreseen extensions include:

    • polarisation in g conversion

    • polarisation in Compton effect

    • Doppler broadening

    • Auger electrons

    • models to handle material dependent effects at very low energies

    • reengineering of Penelope models into Geant4

    • components of interest for space/astrophysics applications

    • components of interest for medical applications

Software process improvement

Huge effort invested into SPI

started from level 0

chaotic, left to heroic improvisation

On-going process

the results of the assessment are probably already quite obsolete for the LowE e.m. WG...

A sample of the improvements:

establishment and management of User Requirements Document

establishment and documentation of procedures

design before coding

designs and testing under configuration management

identification of tasks and responsibilities


...too long to list all the improvements

Software Process Improvement

Internal training
Internal training

  • Substantial investment in the internal training in the WG

    • guided readings

    • code reviews

    • mentoring

    • introduction to basic concepts in software process and OO methodologies

  • Visible effects on the quality of the software and of the process

  • Great interest among the developers

    • who demand more of it

      Perhaps a suggestion for a collaboration-wide programme?


Two system tests

No unit tests

No testing procedures

Physics tests in personal accounts only

No distinction between tests and examples

Suite of unit tests

Suite of physics tests

Two system tests

Tests and examples are separated

Testing procedures

Testing integrated with development





  • Initial situation:

    • no architectural nor detailed design

    • no design process

  • Massive improvement of the design and design process needed

    • spiral cyclic process

    • design iteration in the hadron/ion domain

    • design documentation

  • Reverse engineering of existing classes

  • Further design iterations already planned

  • Education to design and design process in the WG


Top level class diagram

RD44 Geant4alpha

Top level class diagram


Top level class diagram

obtained from reverse engineering...

Design electrons


Design: electrons

Design electrons1


Design: electrons

Design photons


Design: photons

Design photons1


Design: photons

Design hadrons ions


Design:hadrons, ions

(reverse engineering...)


User Documentation

  • Included LowE documentation in Application Developer Guide

  • Expanded LowE documentation in Physics Reference Manual

  • Identified wrong documentation in Toolkit Developer Guide

  • Internal documentation

    • procedures

    • design

    • tests

Web page

Conferences 2000 2001
Conferences 2000-2001

  • CHEP 2000 (2) Padova, February

  • ESA-CERN workshop CERN, April

  • PTCOG Uppsala, April

  • ICCR Heidelberg, May

  • Workshop on Space Radiation Research Arona, May

  • ESTRO Istanbul, September

  • Calor 2000 Annecy, October

  • MC 2000 (3) 3 INFN preprints Lisbon, October

  • AIRO Pisa, October

  • ESTEC TOS-EMA Final Presentation Days ESTEC, December

    Seminars (DESY, Frascati, Genova, Rome, Stockholm, Udine)


General LowE paper

Electrons and photons

Positive hadrons




Space telescope general facility

Brachytherapy general facility

Brachytherapy comparison project

Design of the LowE package


The following publications on refereed journals are planned in the short term:

Drafts already available for some of them

Other activities
Other activities

  • Three advanced examples developed by the LowE WG

    • X-ray telescope

    • g-ray telescope

    • brachytherapy

  • to be released in December

  • Collaboration with AIDA analysis tools group

  • Collaboration with other WGs: UI/GUI, Visualisation

  • The examples/advanced directory has been empty since the time of the Niigata Workshop (July 1998)...

The user community
The user community

  • The WG promotes close contacts with its users

  • Large user community, in expansion

    • excellent relationships with our users

    • users often contact us directly

    • the promotion through conferences, seminars, and web pages plays a fundamental role in the contacts with user communities

  • URD created, maintained and regularly updated

  • Fruitful collaboration with users on testing

Excerpts of communications with users on Problem Reports:

“I really appreciate your support and I know you are doing your best. If you

need any additional information, do not hesitate to contact me.”

“Thank you very much for pointing out the pertinent parameters.

I truly appreciate the time and effort you put into answering my questions.”


We fulfilled all our milestones.

On time.

We hope to have demonstrated to the Collaboration that the creation of the LowE e.m. WG has been fruitful to Geant4