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This study presents the first look at the single muon efficiency in the Wire-Cell imaging system. It provides details on the principle and current status, including the development of a track merging algorithm. Simulation details, pattern recognition, and efficiency calculations are discussed. The results show promising performance, but further improvements and developments are needed.
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First Look of Single Muon Efficiency in Wire-Cell Xin Qian BNL
Recap of Wire-Cell • Details of principle and status can be found in the recent wire-cell summit: • https://indico.physics.lbl.gov/indico/conferenceDisplay.py?confId=258 • Basic steps: • Wire-Cell Imaging • Good shape • Wire-Cell Pattern Recognition • (Still) in progress • Wire-Cell Fine Tracking • Not yet implemented • Will based on existing work (PMA, PID …)
Evaluation of Single Muon Efficiency • Simulation details: • MicroBooNE geometry (MCC6.1) • ~10k isotropic single muon from 0.1-2.0 GeV • Not just straight lines, physics process are on (i.e. multiple scattering, muon decay) • Pattern recognition details: • Based on existing work on pattern recognition • Track ID, vertex fitting, shower identification … • Newly developed track merging alg. • Tracking is still limited inside the connected clusters
Newly Developed Track Merging Before Merging After Merging • In the existing pattern recognition, if there is a vertex connecting three (or more) lines, each line will be identified as a track no matter its property • In the newly developed merging alg., tracks can be merged together according to their (matched) angle, (matched) distance
MC Truth For muons traveling at a very long distance, there is a correlation with its angle due to limitation of the detector size 2.3(H) x 2.56 (D) x 10.x (L)
Calculation of Efficiency • Only muon tracks were studied • Still works to do to properly deal with deltas for merged tracks • Three variables are used to evaluate muon tracking efficiency: • Distance between true starting point and reconstructed track’s end point • Distance between the recorded true end point near the detector boundary and the reconstructed track’s end point • Points along the true track were saved at every ~5 cm? • Length of the true track and reconstructed track
Distributions • Default cut position is indicated by the lines • Note: for the ending points, when the muon tracks travel out the detector volume, we did not calculate the precise ending point, so there is a larger spread • For small reco/true ratio, likely tracks are not totally merged together • For large reco/true ratio, picked up the michel part, also imprecisions in track length calculation due to lack of fine tracking
Efficiencies (I) • Two criteria for good tracks: • Starting points matched < 2 cm && ending points matched < 5 cm • (Starting points matched < 5 cm || ending points matched < 10 cm) && abs(Lreco/Ltrue-1)<0.2 • Also tried abs(Lreco/Ltrue-1)<0.5
Efficiencies (II) • Worse performance for tracks that are parallel to the wire planes (0, 180 degrees) • These tracks tends to be long tracks • Merging algorithms needs to be improved (see next slides)
Some Failed Cases (I) Gaps • http://www.phy.bnl.gov/wire-cell/bee/set/c684fbcd-5386-422f-90d9-56d3e21ad44e/event/0/ • There are gaps existing in the images due to simulations • Gaps lead to separated clusters, good tracking within a cluster • Algorithms to stitch tracks from separated clusters not yet developed
Some Failed Cases (II) • http://www.phy.bnl.gov/wire-cell/bee/set/d35d3ec2-ad07-4b44-a8d7-01f4e3c1c029/event/0/ • A large angle scattering, event was identified as shower (shower ID alg. needs to be improved) • If shower ID is forced to be false, several tracks including michel electrons are IDs
Next Steps • Put results back to LarSoft and use the standard algorithm to calculate efficiency for comparison • Need to properly deal with the left-over merged cells in the track merging steps • Need to develop higher level objects to handle not-connected clusters • Needed to identify shower • Needed to stitch tracks • Needed to deal with gaps in real detectors (special since we know the dead region) • Improve Alg. to deal with real gaps due to unusable channels
Summary • We performed the first look of tracking efficiency for (isotropic + wide momentum range) single muons from wire-cell • Results are promising • Further improvements are expected • Development of pattern recognition is still on-going and is in good progress • Will move into fine tracking soon (PMA, PID, energy, angle, event ID, neutrino selection …)