The H1 Data Preservation Project

The H1 data preservation project was started in 2009 as part of the global data preservation initiative in high-energy physics, DPHEP. In order to retain the full potential for future improvements, the H1 Collaboration aims for level 4 of the DPHEP recommendations, which requires the full simulation and reconstruction chain as well as the data to be preserved for future analysis. A major goal of the H1 project is therefore to provide secure, long-lived and validated access to the H1 data and analysis software, which is realised in collaboration with DESY-IT using virtualisation techniques. By implementing such a system, it is hoped that the lifetime of the unique ep collision data from HERA will be extended, providing the possibility for novel analysis in the future. The preservation of the data and software is performed alongside a consolidation programme of digital and non-digital documentation, some of which dates back to the early 1980s. A new organisational model of the H1 Collaboration, reflecting the change to the long term phase, is to be adopted in July 2012.

💡 Research Summary

The H1 Data Preservation Project, launched in 2009, is a comprehensive effort to safeguard the unique electron‑proton collision data collected at the HERA accelerator and to ensure that the full analysis chain remains usable for future scientific investigations. Aligned with the global DPHEP (Data Preservation in High Energy Physics) initiative, the H1 Collaboration has committed to achieving DPHEP Level 4 preservation, the most ambitious tier, which mandates the retention of raw data, the complete simulation and reconstruction software, and the execution environment required for analysis.

To meet these goals, the project has partnered closely with DESY‑IT to develop a virtualization‑based infrastructure. Original analysis environments, which historically depended on specific operating systems, libraries, and hardware, have been encapsulated into virtual machine (VM) images and lightweight containers. These images are stored in a centrally managed repository, allowing researchers to instantiate an identical software stack on contemporary hardware regardless of future changes in operating systems or computing platforms. The dual approach—VMs for full system fidelity and containers for rapid deployment—provides both robustness and flexibility.

Ensuring the scientific integrity of the preserved assets is a central concern. An automated validation pipeline runs a suite of regression tests that compare reconstructed events, simulated outputs, and legacy analysis results against established benchmarks. Test outcomes are version‑controlled, and any deviation triggers immediate diagnostics and remediation. The project also conducts a thorough audit of external library licenses and, where long‑term support is uncertain, substitutes open‑source alternatives or assumes in‑house maintenance responsibilities.

Documentation, often overlooked in data‑preservation initiatives, receives equal attention. The H1 experiment’s history stretches back to the early 1980s, resulting in a wealth of paper logs, meeting minutes, design schematics, and software manuals that exist only in analog form. These materials are digitized, enriched with searchable metadata, and ingested into a centralized database with strict access‑control and backup policies. This effort guarantees that future analysts can reconstruct the experimental context, understand calibration procedures, and reproduce past analyses with confidence.

Recognizing that long‑term preservation requires stable governance, the collaboration restructured its organizational model in July 2012. Dedicated teams now manage data stewardship, software maintenance, and documentation curation separately, each with clear responsibilities, regular reporting, and performance reviews. This division of labor mitigates risks associated with personnel turnover and institutional changes, ensuring continuity of the preservation activities.

To date, the project has successfully generated validated VM and container images, completed the digitization of the majority of critical documentation, and established a reliable automated testing framework. The anticipated impact is twofold: (1) it extends the scientific lifetime of the H1 dataset, enabling novel physics analyses as theoretical models evolve and new analysis techniques (such as machine‑learning‑based event classification) become available; (2) it provides a replicable blueprint for other high‑energy physics experiments seeking to implement Level 4 preservation. Future work will focus on expanding the user community, offering training workshops, and integrating the preserved environment with emerging grid and cloud resources to maximize accessibility and scientific return.