Alignment of muon chambers with tracks

Transcription

1 Alignment of muon chambers with tracks Sergey Kotov MPI für Physik, Munich MDT Calibration Workshop, Rome, 7.. Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, / 11

2 Tasks for track based alignment Alignment of the ATLAS muon spectrometer relies on an optical alignment system with several subsystems. Specifically, in barrel, sagitta corrections are calculated from readings of the projective alignment sensors Many muon chambers don t have projective optical alignment sensors no correction to sagitta measurement small barrel chambers BEE chambers BIS chambers barrel-to-endcap connection Tracks passing through overlaps between these chambers and optically aligned chambers must be used to obtain their relative positions Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, 7.. / 11

3 Data flow in track based alignment ATHENA Optical alignment and calibration constants TrackSegments with associated RIOs_OnTrack Alignment with segments algorithm Muon track reconstruction Tracking "pseudo" sensors data Muon calibration data stream Preselector of tracks with overlaps (trigger info) Tracks with associated RIOs_OnTrack Alignment with RIOs_OnTrack algorithm ASAP/ ARAMyS Basic features of the track based alignment algorithm It should be an algorithm within ATHENA framework This algorithm should make full use of new tracking EDM (be able to run on both Mounboy and MOORe output) operate with tracking EDM data objects: Track, TrackSegment, RIO_OnTrack use TrackFitters, TrackExtrapolators and other common tracking tools a skeleton of such an algorithm has been written at MPI (MuonTrkAlign package) Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, / 11

4 Structure of MuonTrkAlign algorithm Steps of the MuonTrkAlign algorithm select an overlap region Track with associated RIOs_OnTrack collection from standard muon reconstruction devide this collection into four parts: RIOs_OnTrack coming from large chambers and RIOs_OnTrack coming from small inner/middle/outer chambers refit the large chambers RIOs_OnTrack collection with TrackFitter from common tracking tools, using original track as a seed extrapolate this large chambers track into small chambers with TrackExtrapolator and get track s extrapolated parameters refit inner/middle/outer small chamber RIOs_OnTrack collections with TrackFitter, using extrapolated large chambers track parameters as seed differences between the refitted inner/middle/outer small chamber tracks and the extrapolated large chambers track are the tracking pseudo sensors input for ASAP Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, 7.. / 11

5 Configuration of common tracking tools for MuonTrkAlign release 1.., sample of GeV muons (simulated with 11..) input track container ConvertedMooreTracks or ConvertedMuonboyTracks setup of TrackFitter and TrackExtrapolator Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, / 11

6 Comparison of original Moore track with refitted large chambers track d dperig Entries 191 z zperig Entries Mean.193 RMS 1.7 Mean RMS.151 χ / ndf 9.73 / 15 Constant 3.71 ± / 11 Constant 57.9 ± 3. 7 Mean.5 ±.5 Sigma 1.97 ±.97 Mean ±.19 Sigma.33 ± impact parameters at original track perigee Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, 7.. / 11

7 Comparison of original Moore track with refitted large chambers track φ p phiperig Entries 191 Mean.393 RMS / 37 Constant 7.91 ±.3 Mean.9 ±.77 Sigma.913 ± momperig Entries 191 Mean -.7 RMS / 13 Constant 15. ±. Mean ±.155 Sigma.5 ± θ thetaperig Entries 191 Mean.917 RMS / 17 Constant 13. ±. Mean 3.5e-5 ± 1.319e- Sigma.3 ± momentum parameters at original track perigee Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, / 11

8 Extrapolated large chambers track vs inner small chamber track locrphi 5 lrphiis Entries 1 Mean RMS χ / ndf.75 / 7 locz 5 lzis Entries 1 Mean.5173 RMS 1. χ / ndf 1. / 3 Constant 1.57 ±.9 Mean -. ±.91 Sigma. ±.3 Constant 11.5 ±.9 Mean.35 ±.33 Sigma.5 ± φ phiis Entries 1 Mean.9 RMS / 3 Constant.1 ±.57 Mean.579 ±.117 Sigma.1771 ± θ thetais Entries 1 Mean.17 RMS. 3.3 / 17 Constant 33.9 ±.5 Mean.1 ±.9 Sigma.11 ± major bug just found - wrong orientation of the extrapolation surface, the correct pulls should be much smaller Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, 7.. / 11

9 Extrapolated large chambers track vs middle small chamber track locrphi lrphims Entries 91 Mean.5 RMS χ / ndf 1.77 / 7 Constant 7.93 ± 1. Mean -.5 ± 1.53 Sigma 5.1 ± 9.3 locz lzms Entries 91 Mean -3.3 RMS 5. χ / ndf 1.15 / Constant 13. ±. Mean 3. ± 9.1 Sigma. ± φ phims Entries 91 θ thetams Entries 91 7 Mean. RMS / Constant 3.77 ±.5 Mean.91 ± Mean.15 RMS / 7 Constant 13.3 ±.1 Mean.959 ±.1 Sigma.5 ±.51 1 Sigma.19 ± Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, / 11

10 Extrapolated large chambers track vs outer small chamber track locrphi 3.5 lrphios Entries Mean 31.9 locz lzos Entries Mean. 3 RMS. 5 RMS φ phios θ thetaos Entries Entries 7 Mean RMS.17 1 Mean -.77 RMS Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, / 11

11 Problems and Plans Problems MuonClulsterOnTrack objects (RPCs, TGCs and CSCs) returned by MooreToTrack and MuonboyToTrack tools have D measurement but 1D covariance matrix couldn t find a way to constrain a track parameter (curvature) during the track refit in common tracking tools frequent crashes during refitting due to scatterers in original tracks the current code is just a skeleton of algorithm, so it might have some major bugs Plans fix covariance matrix issue for converted tracks get rid of crashes to be able to run on larger samples tune common tracking tools parameters for use in muon spectrometer code run on a sample of muons with p t=1 GeV Sergey Kotov (MPI für Physik, Munich) Alignment with tracks MDT Calibration Workshop, Rome, / 11