Alignment of Gaps With Cosmic Rays Tom Junk ProtoDUNE Simulation - PowerPoint PPT Presentation

Alignment of Gaps With Cosmic Rays Tom Junk ProtoDUNE Simulation and Reconstruction Meeting November 14, 2018

Alignment • Nearly every detector in HEP is aligned with cosmic rays • Elaborate examples: - CMS: http://arxiv.org/abs/0911.4022 - ALICE: http://arxiv.org/abs/1001.0502 - An ATLAS Ph.D. Thesis: Vincente Lacuesta Miquel http://inspirehep.net/record/1429422/ And another: Regina Moles-Valls http://inspirehep.net/record/1339828/ No specific mention of cosmic rays in either of these, but the idea's the same. Tracks from the collision point are copious at the LHC, but there are "weak directions" 2 11/14/18 T. Junk | Cosmic Ray Alignment

Alignment Constants we Expect to Measure well in DUNE M. Wallbank's thesis: Local deviations from nominal for inter-APA gaps http://inspirehep.net/record/1656784 APA's seen from above, looking down a vertical gap APA APA APA APA z x Need positive ! x or negative ! z Need positive ! x or positive ! z to fix this track (really a combination) to fix this track (really a combination) 3 11/14/18 T. Junk | Cosmic Ray Alignment

Vertical Gap Measurement Precision: 35-ton experience From Mike Wallbank's work on • Stat errors of order 10-50 microns cm 35-ton measurements. Some gaps had more crossing • tracks than others and are thus better measured. Assumes: ! x and ! z are • Error bars constant along the length of the gap on these points are arbitrary " #7 = 1.79×10 -: cm 1tracks " #$ = 5.83×10 -. cm 1tracks 11/14/18 T. Junk | Cosmic Ray Alignment 4

Gap Strategy: ProtoDUNE-SP • Tracks aren't straight in liquid argon, so we select track stubs on either side of an APA gap. • Use SpacePointSolver's SpacePoints as input data • Any ProtoDUNE-SP run will do (need stable HV conditions) – plenty of cosmic rays and beam halo muons. • Current cuts: select space points within 20 cm of a vertical gap, but not within 1 cm. (needs tuning). • Cluster space points based on proximity into stub candidates. • Fit lines in 3D. Require chisquared/DOF < 10 to reduce contaimination from crooked segments and overlapping/interacting particles. 5 11/14/18 T. Junk | Cosmic Ray Alignment

Space Points Near Gaps: X vs Z reco3d SpacePoints for Alignment X Older selection ( c m with 10 cm ) 300 cut around gaps 200 Space point locations 100 are relative to nominal geometry wire locations 0 No attempt made to assign − 100 correct times – not really necessary as segment pairs − 200 come at the same time. − 300 One file from Run 5177 350 400 450 250 300 Z (cm) 6 11/14/18 T. Junk | Cosmic Ray Alignment

Space Points Near Gaps: Y vs Z reco3d SpacePoints for Alignment 600 Y (cm) More ambiguities seen in this view. 500 Beam halo muons in 400 particular tend to be isochronous. 300 200 100 250 300 350 400 450 Z (cm) 7 11/14/18 T. Junk | Cosmic Ray Alignment

A Bee Event Display Space points from isochronous tracks are spread out in Y. Interesting aside: Density of possible space points clusters around a possible track trajectory, but it doesn't line up between APA's. Possible timing misalignment between views? 8 11/14/18 T. Junk | Cosmic Ray Alignment

Gap Strategy, Cont'd • Select pairs of track stubs on either side of the gap • Abs(cos of angle between unit vectors of stubs) > 0.95 • Distance between starting point of one segment and the line of the other segment < 3 cm. 9 11/14/18 T. Junk | Cosmic Ray Alignment

Selected Stub Pairs reco3d SpacePoints for Alignment Space points associated with stubs drawn. 600 One file's worth of data Y (cm) from Run 5177 500 400 Surprisingly low efficiency 300 for vertical-ish tracks. Mostly horizontal tracks pass my 200 selections 100 300 X ( c 200 m ) 100 ) 0 m 450 c ( Z − 100 400 − 350 200 300 − 300 250 10 11/14/18 T. Junk | Cosmic Ray Alignment

An Event in the Collection View Distortions seen near APA boundary. More apparent for steep tracks. Gap in arrival times of charge for steep tracks. I suspect missing charge. Event display tuned by Corey Adams, run by Tingjun Yang. Run 5439 Event 13. APA's 3 and 2 (Beam Right, collection view). 11 11/14/18 T. Junk | Cosmic Ray Alignment

Electron Diverter Installed in beam-right APA's (1, 2, and 3) x z DUNE Doc 1794 (PD-SP TDR) 12 11/14/18 T. Junk | Cosmic Ray Alignment

Effect on Showers Noticed by Aidan Reynolds and James Pillow "flatlands" saturation. 13 11/14/18 T. Junk | Cosmic Ray Alignment

Gap Strategy • Once pairs of segments have been selected, fit their space points jointly to a line in 3D as a function of - gap ! x and - gap ! z • I scanned these from -1 cm to +1 cm in a 2D plane (possible correlations between measurements, but not if we have enough tracks). • Plot sum of line-fit chisquareds in the ( ! x, ! z) plane for each of the four gaps. • Assumes no rotations for now, just translations. 14 11/14/18 T. Junk | Cosmic Ray Alignment

Chisquared vs dx and dz Occasional fit failures Chisq for gap number: 0 Chisq for gap number: 0 Chisq for gap number: 1 Chisq for gap number: 1 dz (cm) dz (cm) give spots on 1 1 30400 22000 30200 pictures – some 21800 30000 0.5 0.5 work to clean up 29800 21600 29600 21400 0 0 29400 Gap numbering: 21200 29200 29000 21000 − − 0.5 0.5 28800 20800 0: upstream, beam right 28600 − 20600 − 1 1 1: upstream, beam left 28400 − − − − 1 0.5 0 0.5 1 1 0.5 0 0.5 1 dx (cm) dx (cm) 2: downstream, beam right Chisq for gap number: 2 Chisq for gap number: 2 Chisq for gap number: 3 Chisq for gap number: 3 3: downstream, beam left 26000 dz (cm) dz (cm) 1 1 34000 33800 25500 One file's worth of data in 0.5 0.5 33600 Run 5833. 33400 25000 0 0 Chisquareds not normalized 33200 33000 (don't have right errors). 24500 − − 0.5 0.5 32800 Strategy: use variations in 32600 24000 fit values over many − − 1 32400 1 − − − − 1 0.5 0 0.5 1 1 0.5 0 0.5 1 dx (cm) dx (cm) samples to determine uncertainties. 15 11/14/18 T. Junk | Cosmic Ray Alignment

Another File of data Chisq for gap number: 0 Chisq for gap number: 0 Chisq for gap number: 1 Chisq for gap number: 1 dz (cm) 24800 dz (cm) 1 1 37200 24600 37000 0.5 0.5 24400 36800 36600 From Run 5834 24200 0 0 36400 24000 36200 Gap numbering: 23800 36000 − − 0.5 0.5 35800 23600 35600 0: upstream, beam right − − 1 1 23400 − − − − 1 0.5 0 0.5 1 1 0.5 0 0.5 1 dx (cm) dx (cm) 1: upstream, beam left Chisq for gap number: 2 Chisq for gap number: 2 Chisq for gap number: 3 Chisq for gap number: 3 2: downstream, beam right 39000 dz (cm) dz (cm) 1 1 3: downstream, beam left 33400 38500 33200 0.5 0.5 Mysterious shift in Z in 33000 38000 the beam-right samples. 32800 0 0 Could be the diverters 32600 37500 causing this. 32400 − − 0.5 0.5 37000 32200 32000 − − 1 1 − − − − 1 0.5 0 0.5 1 1 0.5 0 0.5 1 dx (cm) dx (cm) 16 11/14/18 T. Junk | Cosmic Ray Alignment

Status and Plans • Analysis developed as a ROOT macro using gallery. - convenient, since it runs in an environment where adding a plot and iterating to see what's going on is quick. • Some shortcuts taken (no geometry service for example, so APA boundaries hard-coded in). Configuration parameters not input nicely. Could be made into an art module. • Sanity check – pretend the gaps are in the middle of an APA and fit for distortions. They should be zero. • Need to figure out what the biases and uncertainties are • Only studied ( ! x, ! z) for four gaps, assuming constant ( ! x, ! z) as a function of y for each gap. • Measure ! y and rotations. Six parameters per APA. • Some combinations of parameters will be poorly constrained (e.g. distance between beam-left and beam-right APA planes), at least with this method. • Help is welcome! Patrick Tsang has expressed interest. I wanted to clean up my script and remove egregious bugs first – done! 17 11/14/18 T. Junk | Cosmic Ray Alignment

Electrons should still drift Effect on the Drift mostly in the x direction, but have their arrival times distorted. Due to Rotations position distortions may be more noticeable viewed from above for tracks that go near the APA's 11/14/18 18 T. Junk | Cosmic Ray Alignment

Effect on the Drift • Field distortions due to misaligned cathode and anode planes are expected to be localized near the distorted element. • Go far away from the distorted panel/APA, and the field should be asymptotically uniform. May need to do a calculation to see just how local this is • But – electron arrival time distortions occur for charge drifting from anywhere in the drift volume due to field distortions at the anode • And cathode field distortions only affect tracks close to the cathode. 19 11/14/18 T. Junk | Cosmic Ray Alignment