Part I - Past Activities

III - Computing Infrastructure, Sim and Recon

A - Infrastructure

For the past 10+ years SLAC has been the lead laboratory in the US for linear collider detector R&D computing effort. We have developed flexible tools to allow simulation and reconstruction of detectors in sufficient detail to allow realistic comparison of the capabilities of detector technologies and associated reconstruction algorithms. An emphasis of the group has been on developing infrastructure to allow physicists from universities and other labs to rapidly get started and contribute to detector R&D.

There are significant differences in the design of such tools compared to typical experiment specific simulation and reconstruction code.

• The tools must allow easy reconfiguration to support different detector geometries and technologies.
• The tools must make it easy to develop new reconstruction algorithms and plug them in to the existing reconstruction infrastructure.
• The tools must be very easy for users to set up and become productive. Typically physicists working on detector R&D do so with only a fraction of their effort, and often new graduate students or post-docs take over the work after one or two years.
• The tools must work on a wide variety of operating systems. Unlike established collaborations which can require collaborators' computing platforms to meet certain standards, detector R&D software must work on whatever computing platforms are available to users.
• The tools must be easy to develop and support using a fraction of the manpower that would be available to an established physics collaboration.

The major tools created to meet these design goals are the SLIC Geant4 based simulation program the Java based org.lcsim reconstruction and analysis tools suite, including the WIRED event display and JAS3 data analysis system.

SLIC is a C++ program based on Geant4 which supports reading standard event generator level input (stdhep) and generates LCIO output files. Rather than having detector geometry built-in to the code, SLIC reads the detector geomtry at runtime from an XML detector description. The detector description is based on the standard GDML geometry format developed at CERN, but extended to allow detector response to also be specified in the XML file.

Both org.lcsim and SLIC work with a common high level "compact detector description" which makes it easy to adjust detector parameters and ensure consistency between the simulated and reconstructed data.

These tools were designed to be easy to use and set up so that barrier for users to get involved with the detector simulation effort are low. For several workshops and conferences in the past we have been able to create CDs containing everything a new user needs to get started with these tools, including install kits for a variety of operating systems, documentation and event samples.

In addition to direct support of these tools the SLAC group has:

• Taken a leading role in the creation and support of LCIO standards to ensure a large degree of interoperability with other efforts in Europe and Asia. The LCIO libraries provide a fully documented standard format for reading and writing events at the generator level, full simulation level, or reconstruction and analysis level. The LCIO libraries support C++, Fortran and Java.
• Made available a large collection of standard simulation samples for a variety of event types and standard detector and accelerator configurations.
• Hosted infrastructure shared with related efforts worldwide the including the
  • lcsim.org web site,
  • ILC and SiD related content on the confluence wiki(confluence.slac.stanford.edu) including many detailed tutorials and reference documentation.
  • Discussion forums at forum.linearcollider.org. These are the primary means of providing support to end users who have questions or problems using the software, as well as for discussion between software developers world-wide.
  • CVS repository at cvs.freehep.org and automated continuous build system (hudson). This repository is used to host the LCIO libraries, the core SLIC and org.lcsim software and many user contributed analysis algorithms and tools.

Part II Future Plans

III - Computing Infrastructure, Sim and Recon

Support for infrastructure has stalled since layoffs, in particular ability to respond to user requested enhancements and bug fixes has been very limited. Much of the infrastructure used by the SiD effort is shared with other groups at SLAC and we expect the support for this to be co-ordinated with them.

On going support for getting users started with framework.

Goals:

• LCIOv2 – in collaboration with other LCIO developers.
  • Support more detailed reconstruction output based on experience for LoI studies.
  • Support for more efficient analysis of large data samples, including efficient random access to selected events.
• Update SLIC to use latest GDML standards. Support for more realistic detector mechanics and response modeling.
• Update documentation and tutorials, especially to integrate new reconstruction tools developed for LoI.
• Enhanced geometry system able to handle increasingly detailed detector descriptions. Explore common geometry description with others
• Enhance interoperability with other tools. Work around limitations of Root.
• Update plugins for use with JAS
• Improved plotting, especially for publication quality plots
• Improved documentation on AIDA, especially in the area of fitting, advanced plots.
• Run org.lcsim on many-core CPU's