About

I'm a software engineer at CERN, in the LHCb Computing Section, working on the distributed data-processing infrastructure and software stack that supports the LHCb experiment and its physicists. In practice that means the Analysis Productions platform, CWL-based workflows for the DiracX grid middleware, and the operations tooling that keeps thousands of grid jobs running concurrently.

Ryunosuke O'Neil presenting at CHEP 2026 in Bangkok, holding a microphone in front of a session backdrop.
Presenting at CHEP 2026

I came to software engineering through physics. During my PhD in the Particle Physics Experiment group at the University of Edinburgh, I led a search for excited charmed baryons over LHCb's Run 2 dataset, which resulted in the observation of a new state, the Ξc(2923)+, published in Physical Review Letters. Producing the n-tuples for that analysis made me an intensive user of the very tooling I would later rebuild: alongside the physics, I created LbAPWeb, the web application LHCb analysts now use to create and manage their datasets. The motivation came directly from knowing, first-hand, where the frustrations were.

Earlier, I spent time closer to the detectors: two testbeam campaigns at the DESY-II facility in 2022, evaluating irradiated HV-MAPS sensors for the LHCb MightyPix project, and before that a Masters at the University of Manchester on data-driven alignment of the tracker for the Mu2e experiment at Fermilab, using cosmic ray simulations to test it.

Most of my work happens in the open; You can see what I've been up to recently on my GitHub and CERN GitLab.

Theses and publications