ACAT 2019

Abstracts

DD4hep: an integrated detector description tool for HEP

• Speaker: Markus Frank, Frank-Dieter Gaede, Marko Petric, Andre Sailer
• Status: Poster
• Abstract: The detector description is an essential component in simulation, reconstruction and analysis of data resulting from particle collisions in high energy physics experiments. The main motivation behind DD4hep is to provide an integrated solution for all these stages and addresses detector description in a broad sense, including the geometry and the materials used in the device, and additional parameters describing e.g. the detection techniques, constants required for alignment and calibration, description of the readout structures and conditions data. A core part of DD4hep is DDG4 which is a powerful tool that converts arbitrary DD4hep detector geometries to Geant4 and gives access to all Geant4 action stages. It is equipped with a comprehensive plugins suite that includes handling of different IO formats, Monte Carlo truth linking and a large set of segmentation and sensitive detector classes, allowing the simulation of a wide variety of detector technologies. Another important segment of the toolkit are DDCond and DDAlign, which expose a mechanism to manage detector data simultaneously for multiple versions depending on their validity. The detector conditions data are made available to the physics algorithms through a number of transient objects grouped to collections. Such a collection represents a coherent slice of all conditions data necessary to process one or several events depending on the interval of validity of the slice, which is the intersection of the individual conditions. A multi-threaded application may hold several such collections in parallel depending on the time-stamps of the events currently processed. In this presentation, we will give an overview of the project and discuss developments in DD4hep as well as showcase recent adaptions of the framework by LHC experiments and beyond.
• Poster

ConformalTracking: a geometry agnostic tracking library

• Authors: Erica Brondolin, Daniel Hynds, Emilia Leogrande, Marko Petric, Andre Sailer
• Status: accepted for Oral presentation
• Abstract: ConformalTracking is an open source library created in 2015 to serve as a detector independent solution for track reconstruction in detector development studies at CERN. Pattern recognition is one of the most CPU intensive tasks of event reconstruction at present and future experiments. Current tracking programs of the LHC experiments are mostly tightly linked to individual detector descriptions or event processing frameworks. ConformalTracking does a pattern recognition in a conformal-mapped plane, where helix trajectories of charged particles in a magnetic field are projected into straight lines, followed by a Kalman-Filter-based fit in global space. At the core of the library lies a nearest neighbour search that is optimized by means of fast KDTrees and enhanced with a cellular automaton to reconstruct the linear paths. Being based exclusively on the spatial coordinates of the hits, this algorithm is adaptable to different detector designs and beam conditions. In the detectors at CLIC and FCCee, it also profits from the low-mass silicon tracking system, which reduces complications from multiple scattering and interactions. Full-simulation studies have been performed in order to validate the algorithm and assess its performances, also in the presence of beam-induced background. In this talk, recent developments and features of the track reconstruction chain as well as results for isolated tracks and complex events with background will be discussed.
• Slides

DIRACOS: a cross platform solution for grid tools

• Authors: Ben Couturier, Christophe Haen, Marko Petric
• Status: Poster
• Abstract: All grid middleware require external packages to interact with computing elements, storage sites… In the case of the DIRAC middleware this was historically divided into two bundles, one called externals containing Python and standard binary libraries and the other called the LCGBundle containig libraries form the grid world (gfal, arc, etc). The externals were provided for several platforms whereas the LCGBundle was released only for SLC6 and CC7. Such a setup was difficult to test and hindered agile development of DIRAC. Therefore we developed DIRACOS to produce a coherent environment for grid interaction. Additionally it solves the binary incompatibility we reached by using a python version newer than the native system one (SLC6). It is spawned form a single list of required packages from where we use SRPMs to pull all dependencies down to the level of glibc. With such an approach we can provide the same packages for our clients, servers, and several platforms. It is an extendible setup with an agile development cycle in mind. The core build functionality of DIRACOS is based on Fedora Mock. DIRACOS also introduces its own grammar, and to handle specific cases it also allows patching (some SRPM require tweeking, which the user can do by providing a diff) as well as routines for pre/post/instead actions of compilation. With this approach DIRAC was able to provide a single bundle for clients and servers, that is reliable, flexible, easy to test and relatively small (250 MB). It allows for a smooth transition from SLC6 to CC7 and provides a clear roadmap for possible extension of DIRAC to a myriad of platforms.
• Poster