Speaker
Dr
Alberto Ribon
(CERN)
Description
Geant4 is a general purpose toolkit for simulating the tracking
and interaction of particles through matter. It is currently used
in production in several particle physics experiments (BaBar, HARP,
ATLAS, CMS, LHCb), and it has also applications in other areas,
as space science, medical applications, and radiation studies.
The complexity of the Geant4 code requires careful testing of all
of its components, especially before major releases (which happens
twice a year, in June and December).
In this talk, I will describe the recent development of an automatic
suite for testing hadronic physics in high energy calorimetry
applications. The idea is to use a simplified set of hadronic
calorimeters, with different beam particle types, and various beam
energies, and comparing relevant observables between a given
reference version of Geant4 and the new candidate one. Only those
distributions that are statistically incompatible are then printed
out and finally inspected by a person to look for possible bugs.
The suite is made of Python scripts, and utilizes the "Statistical
Toolkit" for the statistical tests between pair of distributions,
and runs on the Grid to cope with the large amount of CPU needed
in a short period of time. In fact, the total CPU time required for
each of these Geant4 release validation productions amounts to about
4 CPU-years, which have to be concentrated in a couple of weeks.
Therefore, the Grid environment is the natural candidate to perform
this validation production. We have already run three of them,
starting in December 2004. In the last production, in December 2005,
we run as Geant4 VO, for the first time, demonstrating the full
involvement of Geant4 inside the EGEE communities. Several EGEE sites
have provided us with the needed CPU, and this has guaranteed the
success of the production, arriving to an overall efficiency rate
of about 99%.
In the talk, emphasis will be given on our experiences in using
the Grid, the results we got from it and possible future
improvements. Technical aspects of the Grid framework that have
been deployed for the production will only be mentioned; for more
details see the talks of P.Mendez and J.Moscicki.
Author
Dr
Alberto Ribon
(CERN)
