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New setup for track-based luminosity in PbPb

Kartik Deepak Bhide requested to merge kbhide/athena:idlumi-heavyion into 24.0

This merge request adds a new reconstruction setup in release 24 for track-based luminosity measurement in PbPb collisions, called "VtxLumiHeavyIon", based on the existing "VtxLumi" flags used for track-based luminosity measurement in pp collisions. It's a hybrid setup, based on "VtxLumi", with some flags taken from the heavy-ion physics setup.

Some validation has been performed, comparing the new setup with a release 22 setup that was used during 2023 PbPb data taking. The release 22 setup was achieved entirely through --preExec in Reco_tf.py, hence there is no corresponding release 22 "VtxLumiHeavyIon". The slides for the validation are here.

Unfortunately the release 22 - release 24 comparison is not perfect in terms of low-level quantities (number of track hits, holes etc). However, there is no impact on the high level quantitiy, namely the visible pileup with track-based event counting.

We hope to use this new reconstruction setup for 2024 PbPb data taking. Given the use case, and the tight schedule w.r.t. the run, the Inner Detector Luminosity sub-conveners (@fdattola and @lrossini) support this imperfect (in terms of release22-release24 comparison) merge request. We plan to investigate the observed release22-release24 differences in much more detail after 2024 PbPb data taking. I'm happy to answer any questions.

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