Test67 for the verification of EM models

Luciano PandolaINFN – LNGS

Intercomparison exercise In 2007 a “comparison exercise”

has been performed within the -ray spectrometry community

Goal: compare detection efficiencies predicted by different MC codes for a given (simplified) geometry of interest

each participant submitted the results calculated with his/her favourite MC code

participants used Geant4, Geant3, PENELOPE, MCNP, EGS et al.

Appl. Rad. Isotopes 66 (2008) 764 found differences up to 10% at

very low energy. Typically < few % Use this setup as a benchmark for

the existing and new EM models in Geant4 test67

Check EM physics with test67

The same test67 job is sistematically run at each new reference tag, using several EM builders

6 energies between 45 keV and 2000 keV 5·106 events/run

Convenient way to: test for anomalies/bugs, possibly introduced in the

development Cross-check the stability of results and the

consistency of the EM builders Benchmark the CPU performances of each builder and

track for improvements Results available at

/afs/cern.ch/sw/geant4/user/vnivanch/verification/electromagnetic/test67

Stability of results vs. tag, G4EmPenelopePhysics

Full peak efficiency at 120 keV (nominal geometry configuration) stable vs. Geant4-ref

tag

Full

peak

effi

cien

cy a

t 120

keV

(%

) 09-0

5-r

ef-

09

09-0

4-r

ef-

01

Penelope v2008

Penelope v2001

Stability of results vs. tag, G4EmStandardPhysics_option3 Fu

ll peak

effi

cien

cy a

t 120

keV

(%

)

09-0

5-r

ef-

09

09-0

4-r

ef-

05

Major variation in result seen in 09-05-ref-09 feedback to Vladimir. Due to a bug, immediately fixed in tags emstand-V09-05-53 and emutils-V09-05-43

Benchmark of CPU performances

Opt0 Opt3 Opt4 Penelope Livermore

09-05-ref-09

579 786 968 835 914

09-05-ref-08

600 711 - 866 947

09-05-ref-07

576 669 - 825 897

09-05-ref-06

559 853 - 841 1143

09-05-ref-05

565 898 - 869 1174

09-05-ref-04

551 869 - 837 1120

At each new reference tag, the same test67 job is executed on pcgeant08@CERN using different EM builders. Absolute numbers are meaningless, but it is interesting to check for relative differences between different models and/or different Geant4 tags

Clear improvement for Opt3 and Livermore between ref-06 and ref-07 (new Rayleigh scattering model)

Backup

Comparison with other codes

Results from Geant4-sim can be compared also with reference values obtained with other codes in the intercomparison exercise

error bars in the reference values are the spread of results provided by participants who used the same code

Good agreement with EGS, Geant4 (of course!), Penelope (of course!)

Total efficiency at 120 keV

Peak efficiency at 120 keV

Summary Test (test67) available in Geant4 to implement the

intercomparison exercise of Appl. Rad. Iso. 66 (2008) 764

well-defined geometry, typical use-case of -ray spectroscopy Results obtained with the dev version of Geant4 can be

compared with the reference results reported in the intercomparison and obtained with different MC tools

way to quickly check for (big) bugs during the development scripts and processing tools already available

Convenient way also to monitor the stability vs. reference tag of several parameters

not only efficiencies, but also fluorescence yield, spectra, etc. The application is able to handle all sets of EM models,

though more focus was given to Penelope, up to now good performance of EM models (results and stability)