HELPMI: Helmholtz Laser-Plasma Metadata Initiative

HELPMI will develop a metadata standard for experimental data of the global laser-plasma community. To date, this community is widely using openPMD, an open meta-standard, established for the domain of simulations.

At most laser-plasma research laboratories, type and format of experimental data and metadata are heterogeneous and complex. The data originate from several distinct sources, occur at various levels and at different times during an experimental campaign. Some metadata such as project names and proposal IDs appear usually quite early during an experimental project, while exact time stamps of experimental data or acquisition parameters of diagnostics are generated during the runtime. Similarly, data can originate as early from target pre-characterization, during the experiment’s setup phase and diagnostic calibration runs or ultimately from actual laser shots. Furthermore, the configuration and status of deployed diagnostics and therefore the experimental arrangement are often subject to changes during a campaign, also with very short notice and sometimes without previous planning but as a consequence of experimental results. Beyond, there is a strong need for better data integration and enrichment in the field of high-intensity laser-plasma physics in international context. This has become clear during several online events, e.g. the LPA Online Workshop on Machine Learning and Control Systems , the Laserlab-Europe – ELI – CASUS workshop or NFDI events . Setting out from this status quo and given their leading expertise in laser-driven experiments, HZDR, HI Jena and GSI will develop a metadata standard for the high-intensity laser-plasma community, with an initial emphasis on ion facilities during this project.

Proposed Work

• Glossary and Ontology: A significant effort is required to conceive a sensible, widely applicable dictionary of concepts of data and metadata associated with the field. A reasonably close exchange to the worldwide community is planned via project observers and dedicated workshops. lead: HI Jena

• Technical preparation: Prepare the openPMD standard and its API for custom hierarchies and datasets in general and demonstrate interoperability between NeXus and openPMD in particular. openPMD is a meta-standard originally developed as a data format for a high-performance simulation code and is recently being adopted for other simulation codes, enabling interoperability and easing e.g. analysis efforts due to existing software concomitant to openPMD. There is a strong interest to increase and facilitate the exchange between simulations and experiments within the laser-plasma community. NeXus on the other hand is a metadata-standard for experiments in the Photon and Neutron science community. We plan to overcome the present boundaries of the two standards. lead: HZDR

• Application of the new metadata standard to concrete cases at participating centers for fast examination.

  GSI: There is no widely-used metadata format yet. Extend the PHELIX database (PSDB) towards the new standard; generation of data and metadata.

  HI Jena: Conduct a pilot beamtime and generate experimental data with metadata.

  HZDR: Apply the new standard to research data at HZDR and generate a data object on RODARE for demonstration of FAIR access.

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