Simulation of radiation and background levels in an underground experiment rely heavily on an accurate description of the geometry of the detector and of the experimental hall: equally important is the chemical composition (materials) of all volumes. In particular, given the particular nature of the ATLAS muon spectrometer (an open-air toroid with very little shielding behind the calorimeters), an accurate description of the muon spectrometer and of the cavern (including access shafts, plugs and in general service infrastructures) are of paramount importance when evaluating precisely the neutron fluxes and cavern background simulation.
Whilst the geometry of the spectrometer is well understood (see WPI), the geometry of the cavern is basic in terms of detail and the code is under-maintained and inadequately documented. Furthermore, the geometry description contains volume overlap bugs, which currently block new background simulation.
The cavern geometry code should be replaced with an XML-based (AGDD) description that, while inspired by the existing one, can be fixed and developed freely by the team to cover the requirements of any background simulation (or any other connected activity such as cosmic simulation).
The team should develop:
a good knowledge of the experimental layout, including the cavern (CATIA) a good knowledge of the AGDD infrastructure
The team should work in close collaboration and consultation with:
a). the background/radiation simulation group, who have a clear understanding of the physics requirements.
b) The simulation group for the integration in the main simulation line/infrastructure.
c) The detector description group, especially regarding tools and future developments.
The team should make regular reports to the simulation and detector description group meetings and interact directly with members of those groups. Visits to CERN by members of the Georgian team working on this work package are required.
After this work is completed, the team should work closely with the simulation and detector description groups in the larger task of porting the whole of the muon spectrometer+cavern to the newly developed detector description system. New milestones for this can be defined at a later date.
ATLAS Project: Software and Computing
ATLAS contact person: Andrea Dell\'Acqua and Joseph Boudreau
Required effort from Georgian team: 3 FTE/CATIA designers, programmers