CHEP 2016

Using OSG Computing Resources with (iLC)DIRAC

• Speaker: Andre Sailer (CERN)
• Author: Marko Petric (CERN), Andre Sailer (CERN)
• Status: accepted as poster
• Abstract: CPU cycles for small experiments and projects can be scarce, thus making use of all available resources, whether dedicated or opportunistic, is mandatory. While enabling uniform access to the LCG computing elements (ARC, CREAM), the DIRAC grid interware was not able to use OSG computing elements (GlobusCE, HTCondor-CE) without dedicated support at the grid site through so called 'SiteDirectors', which directly submits to the local batch system. Which in turn requires additional dedicated effort for small experiments on the grid site. Adding interfaces to the OSG CEs through the respective grid middleware is therefore allowing accessing them within the DIRAC software without additional site-specific infrastructure. Thus enabling greater use of opportunistic resources for experiments and projects without dedicated clusters or an established computing infrastructure with the DIRAC software. To send jobs to HTCondor-CE and legacy Globus computing elements inside DIRAC the required wrapper modules were developed. Not only is the usage these types of computing elements now completely transparent for all DIRAC instances, which makes DIRAC a flexible solution for OSG based virtual organisations, but also allows LCG Grid Sites to move to the HTCondor-CE software, without shutting DIRAC based VOs out of their site. In this presentation we detail how we interfaced the DIRAC system to the HTCondor-CE and Globus computing elements and explain the encountered obstacles and solutions or workarounds developed, and how the linear collider uses resources in the OSG.
• poster

Detector Simulations with DD4hep

• Speaker: Marko Petric (CERN)
• Authors: Andre Sailer (CERN), Frank-Dieter Gaede (Deutsches Elektronen-Synchrotron (DE)), Marko Petric (CERN), Nikiforos Nikiforou (CERN), Markus Frank (CERN), Shaojun Lu (DESY)
• Status: accepted as oral presentation
• Abstract: Detector design studies, test beam analyses, or other small particle physics experiments require the simulation of more and more detector geometries and event types, while lacking the resources to build full scale Geant4 applications from scratch. Therefore an easy-to-use yet flexible and powerful simulation program that solves this common problem but can also be adapted to specific requirements is needed. The groups supporting studies of the linear collider detector concepts ILD, SiD and CLICdp as well as detector development collaborations CALICE and FCal have chosen to use the DD4hep geometry framework and its DDG4 pathway to Geant4 for this purpose. DD4hep with DDG4 offers a powerful tool to create arbitrary detector geometries and gives access to all Geant4 action stages. The DDG4 plugins suite includes the handling of a wide variety of input formats; access to the Geant4 particle gun or general particles source; the handling of Monte Carlo truth information -- e.g., linking hits and the primary particle that caused them -- indispensable for performance and efficiency studies. An extendable array of segmentations and sensitive detector allows the simulation of a wide variety of detector technologies. In this presentation we will show how our DD4hep based simulation program allows one to perform complex Geant4 detector simulations without compiling a single line of additional code by providing a palette of sub-detector components that can be combined and configured via compact XML files, and steering the simulation either completely via the command line or via simple python steering files interpreted by a python executable. We will also show how additional plugins and extensions can be created to increase the functionality.
• slides

DD4hep based event reconstruction

• Speaker: Andre Sailer (CERN)
• Authors: Frank-Dieter Gaede (Deutsches Elektronen-Synchrotron (DE)), Markus Frank (CERN), Daniel Hynds (CERN), Shaojun Lu (DESY), Nikiforos Nikiforou (CERN), Marko Petric (CERN), Andre Sailer (CERN), Rosa Simoniello (CERN), Georgios Gerasimos Voutsinas (DESY)
• Status: accepted as oral presentation
• Abstract: The DD4hep detector description tool-kit offers a flexible and easy to use solution for the consistent and complete description of particle physics detectors in one single system. The sub-component DDRec provides a dedicated interface to the detector geometry as needed for event reconstruction. With DDRec there is no need to define an additional, separate reconstruction geometry as is often done in HEP, but one can transparently extend the existing detailed simulation model to be also used for the reconstruction. Based on the extension mechanism of DD4hep, DDRec allows one to attach user defined data structures to detector elements at all levels of the geometry hierarchy. These data structures define a high level view onto the detectors describing their physical properties, such as measurement layers, point resolutions and cell sizes. For the purpose of charged particles track reconstruction dedicated surface objects can be attached to every volume in the detector geometry. These surfaces provide the measurement directions, local-to-global coordinate transforms and material properties. The material properties, essential for the correct treatment of multiple scattering and energy loss effects, are automatically averaged from the detailed geometry model along the normal of the surface. Additionally a generic interface allows the user to query material properties at any given point or between any two points in the detector's world volume. In this talk we will present DDRec and how it is used together with the generic tracking toolkit aidaTT and the the particle flow package PandoraPFA for full event reconstruction of the ILC detector concepts ILD and SiD and of CLICdp. This flexible tool chain is also well suited for other future accelerator projects such as FCC and CEPC.
• slides