The ATLAS Collaboration at CERN,has been leading efforts to promote transparency and accessibility through its comprehensive open data initiatives. These efforts are designed to benefit researchers, educators, and the public, enhancing both scientific discovery and educational outreach. The sheer volume and complexity of the data generated by the ATLAS experiment necessitate innovative strategies for analysis and interpretation. Recognizing the value of making this data available to the broader scientific community and the public, ATLAS has committed to an open data policy that aligns with the principles of open science.

Central to this initiative is the ATLAS Open Data Portal, which provides detailed datasets from various LHC runs. The portal offers a wealth of information, including collision data, metadata, and analysis tools. By making these resources available, ATLAS aims to democratize access to high-energy physics data, enabling researchers worldwide to engage in novel analyses and educators to develop enriched science curricula.

The 13 TeV Data Release

In a significant move to support both research and education, ATLAS released 13 TeV collision data in February 2020. This dataset includes information from the high-energy proton-proton collisions that are pivotal to probing new physics beyond the Standard Model. By providing access to this data, ATLAS empowers the scientific community to conduct independent analyses, verify existing results, and explore new theoretical models.

The ATLAS Collaboration made public 10 inverse femtobarns (fb^–1) of the 13 TeV data, corresponding to about 1 quadrillion proton-proton collisions (that’s 1 followed by 15 zeros), or 500 thousand produced Higgs bosons. This is also approximately the same amount of data that the ATLAS Collaboration used to discover the Higgs boson in 2012. The ATLAS Open Data can be explored by using the software and tools available here and on CERN's Open Data Portal.

Another groundbreaking aspect of ATLAS’s open data efforts is the release of open likelihoods in December 2019. Likelihoods are essential statistical tools that summarize the compatibility of theoretical models with experimental data. The open release of these likelihoods facilitates deeper collaboration between experimental and theoretical physicists, allowing for rigorous testing of new hypotheses and models against existing data. 

Compact Data Formats

An important advancement that has facilitated these open data releases is the use of new and more compact data formats. In particular, ATLAS has introduced a new “slim” data format for Run 3 data as discussed in a previous issue of the EP newsletter. This format significantly reduces the size of datasets without losing critical information, making it easier and faster for researchers to download and analyze the data. These compact formats optimize storage and accessibility, enhancing the overall efficiency of data handling and processing. In the recent analysis of ZZ boson production at 13.6 TeV, the PHYSLITE format proved effective, reducing CPU usage by 25% and data size by a factor of three compared to previous formats. This innovation aims to optimize ATLAS’s computing resources as data volumes increase in future LHC runs.

Educational Impact and Tools

ATLAS’s open data initiatives are not limited to researchers. The collaboration also focuses on developing educational resources and user-friendly tools that make complex data more accessible to students and educators. These tools are designed to lower the barriers to understanding particle physics, enabling a broader audience to engage with the science and potentially inspire the next generation of physicists.

Future Directions

Looking ahead, ATLAS plans to continue expanding its open data efforts. This includes regular releases of new data sets, open likelihoods, and associated analysis tools. By maintaining a robust open data policy, ATLAS aims to foster an inclusive and collaborative scientific.

The ATLAS Collaboration’s commitment to open data is a testament to the value of transparency and collaboration in scientific research. By making their data and analysis tools available to the global community, ATLAS enhances the transparency of their research and contributes to the broader advancement of knowledge in particle physics. These efforts set a benchmark for other large-scale scientific experiments, highlighting the importance of openness in driving scientific progress and education.

For more information, you can explore the ATLAS Open Data Portal and discover the wealth of resources available.