CERN Accelerating science

ATLAS Note
Report number	ATL-SOFT-PROC-2023-003
Title	Framework for custom event sample augmentations for ATLAS analysis data
Author(s)	Van Gemmeren, Peter (Argonne National Laboratory (US)) (+) ; Mete, Alaettin Serhan (Argonne National Laboratory (US)) ; Nowak, Marcin Jerzy (Brookhaven National Laboratory (US)) ; Catmore, James (University of Oslo (NO)) ; Burzynski, Jackson Carl (Simon Fraser University (CA)) ; Krumnack, Nils Erik (Iowa State University (US)) ; Heinrich, Lukas Alexander (Technische Universitat Munchen (DE))
Corporate Author(s)	The ATLAS collaboration
Collaboration	ATLAS Collaboration
Publication	2024
Imprint	02 Aug 2023
Number of pages	6
In:	EPJ Web Conf. 295 (2024) 03016
In:	26th International Conference on Computing in High Energy & Nuclear Physics, Norfolk, Virginia, Us, 8 - 12 May 2023
DOI	10.1051/epjconf/202429503016
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Abstract	For HEP event processing, data is typically stored in column-wise synchronized containers, such as most prominently ROOT’s TTree, which have been used for several decades to store by now over 1 exabyte. These containers can combine row-wise association capabilities needed by most HEP event processing frameworks (e.g. Athena for ATLAS) with column-wise storage, which typically results in better compression and more efficient support for many analysis use-cases. One disadvantage is that these containers, TTree in the HEP use-case, require to contain the same attributes for each entry/row (representing events), which can make extending the list of attributes very costly in storage, even if those are only required for a small subsample of events. Since the initial design, the ATLAS software framework features powerful navigational infrastructure to allow storing custom data extensions for subsample of events in separate, but synchronized containers. This allows adding event augmentations to ATLAS standard data products (such as DAOD-PHYS or PHYSLITE) avoiding duplication of those core data products, while limiting their size increase. For this functionality, the framework does not rely on any associations made by the I/O technology (i.e. ROOT), however it supports TTree friends and builds the associated index to allow for analysis outside of the ATLAS framework. A prototype based on the Long-Lived Particle search is implemented and preliminary results with this prototype will be presented. At this point, augmented data are stored within the same file as the core data. Storing them in separate files will be investigated in future, as this could provide more flexibility, e.g. certain sites may only want a subset of several augmentations or augmentations can be archived to disk once their analysis is complete.

Corresponding record in: Inspire