Missing tracks in the B0 tracking sequence

[michael-pitt]

Environment: (where does this bug occur, have you tried other environments)

• Which branch: main

Steps to reproduce: (give a step by step account of how to trigger the bug)

There is some issue with running ACTs on the B0 hits in a given theta range. I would appreciate any expert looking into the problem and suggesting how to debug the code.

B0 tracking detector should reconstruct charged particles in 5.5 mrad < theta < 23 mrad range. For some reason, tracks within 5.5 < mrad < theta < 9 mrad are not reconstructed (but the reconstructed hits are available).

The EICRecon sequence correctly reconstructs the measurements (B0TrackerRecHits), and initial track parameters (using true seeding) but fails to return tracks for seeds: https://github.com/eic/EICrecon/blob/main/src/algorithms/tracking/CKFTracking.cc#L266 doesn't return any tracks for seed (as usually happens when the tracks are with theta > 9 mad). To reproduce the simulations:

1. run Detector simulation:

source /opt/detector/epic-main/bin/thisepic.sh
npsim --steeringFile minimal.py -G -N 100 --compactFile $DETECTOR_PATH/epic_craterlake_18x275.xml --gun.momentumMin "250*GeV" --gun.momentumMax "250*GeV" --gun.thetaMin "7.0*mrad" --gun.thetaMax "8.0*mrad" --crossingAngleBoost -0.025 --gun.particle "proton" --gun.distribution "eta" --outputFile edm4hep.root

(the file was copied to /gpfs/mnt/gpfs02/eic/mpitt/public/Simulation/test/edm4hep.root, simulation takes 17 minutes to run)

2. run EICRecon reconstruction:

source /opt/detector/epic-main/bin/thisepic.sh
eicrecon -Pjana:nevents=-1 -Pdd4hep:xml_files=$DETECTOR_PATH/epic_craterlake_18x275.xml -Ppodio:output_collections=MCParticles,B0TrackerRecHits,ReconstructedTruthSeededChargedParticles edm4hep.root

(the file was copied to /gpfs/mnt/gpfs02/eic/mpitt/public/Simulation/test/podio_output.root)

Expected Result: (what do you expect when you execute the steps above)

We expect tracks stored in ReconstructedTruthSeededChargedParticles container.
We can print the reconstructed track pZ, generated track pZ, and number of all hits in B0 tracker, using:

root -l podio_output.root
events->Scan("ReconstructedTruthSeededChargedParticles.momentum.z : MCParticles.momentum.z[0] : Sum$(B0TrackerRecHits.position.z>0)")

Actual Result: (what do you get when you execute the steps above)

There are no reconstructed tracks (while we have hits in all tracking layers):

***********************************************************
*    Row   * Instance * Reconstru *  MCPartic *  Sum$(B0T *
***********************************************************
*        0 *        0 *           * 249.99218 *         5 *
*        1 *        0 *           * 249.99379 *         4 *
*        2 *        0 *           * 249.99220 *         4 *
*        3 *        0 *           * 249.99380 *         4 *
*        4 *        0 *           * 249.99354 *         4 *
*        5 *        0 *           * 249.99353 *         4 *
*        6 *        0 *           * 249.99292 *         7 *
*        7 *        0 *           * 249.99235 *         4 *
*        8 *        0 *           * 249.99247 *         4 *
*        9 *        0 *           * 249.99200 *         6 *
*       10 *        0 *           * 249.99313 *         4 *
*       11 *        0 *           * 249.99372 *         4 *
*       12 *        0 *           * 249.99359 *         4 *

Many warnings of the following form:

[tracking:CentralCKFTruthSeededTrajectories] [info] Last trajectory is empty

[michael-pitt]

adding @ajentsch to follow