Testbeam analysis of a single chip timepix3 ingrid Kees Ligtenberg - PowerPoint PPT Presentation

Timepix hits Telescope track pixel z-axis (drift direction) [mm] 16 1.6 14 pixel z-axis (drift direction) [mm] 12 1.4 10 1.2 8 6 1 s] 4 µ ToT [ 0.8 2 0.6 0 2 0.4 4 6 pixel y-axis [mm] 8 0.2 0 10 2 4 12 6 8 0 10 pixel x-axis (beam direction) [mm] 14 12 14 Testbeam analysis of a single chip timepix3 ingrid Kees Ligtenberg Nikhef November 20, 2017 Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 1 / 23

Detector setup Adapted from Thesis Pascal Wolf Bonn, 2016 Triggered by a scintillating plane 6 mimosa planes and timepix3 TPC Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 2 / 23

FEI4 between telescope and TPC Entries Telescope track fit Timepix track fit 50000 40000 30000 20000 10000 0 − − − − 2 1.5 1 0.5 0 0.5 1 1.5 2 Hit residual y [mm] Telescope track has additional smearing compared to timepix3 track Possibly caused by the FEI4-chip being attached to the telescope (for timing in some setups) FEI4 is used for ATLAS IBL that has a radiation length of 1.5%. (And each mimosa plane has 0.1%) Could have caused a scatter of about ∼ 0.7 mRad Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 3 / 23

Time matching Each telescope frame (115.2 µ s) can have a range of triggers Try to decode trigger number in timepix3 using rising edge only Save timepix3 tracks within 400 ns of a trigger For each frame, attempt to match all events of the timepix3 with triggers in the range Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 4 / 23

Cluster finding in telescope and timepix3 Find clusters from hits binned by position Fill 30 × 15 (12 × 12) bins for telescope (TPC) If more than 3 (6) hits in one bin, try to merge up to 8 neighbours If cluster has more than 10 (5) hits update image: mention bins and telescope Histogram of hough transform graphicHistogram graphicHistogram 5 Entries Entries 13 13 14 Mean x Mean x 14.92 14.92 4.5 Mean y Mean y 6.615 6.615 Std Dev x 4.358 Std Dev x 4.358 12 4 Std Dev y 2.058 Std Dev y 2.058 3.5 10 3 8 2.5 6 2 1.5 4 1 2 0.5 0 0 0 5 10 15 20 25 30 Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 5 / 23

Fit procedure Independently align telescope Rotate and shift Timepix3 to match telescope frame Do ToT and time walk corrections Do a double simple linear regression fit in the telescope frame ◮ Errors in directions perpendicular to beam-axis ◮ In telescope frame the tracks direction is almost parallel to beam-axis, therefore errors along beam-axis were neglected Match Timepix3 and telescope clusters Add final plane crossing of telescope as a point with 10 µ m errors to Timepix3 fit Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 6 / 23

Hit errors Assign errors to hit: y = 0 . 055 2 σ 2 + D 2 T ( z − z 0 ) 12 z = (1 . 56 ns ) v drift σ 2 + D 2 L ( z − z 0 ) 12 where D the diffusion coefficient Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 7 / 23

Selection cuts Telescope At least 4 planes hit Fit and reject extreme outliers ( > 700 µ m ) Telescope fit goes through tpc Timepix3 Hit ToT > 0 . 15 µ s At least 20 hits Exactly one cluster Cut hit outliers ( > 3 σ drift , > 2 σ plane ) Fit goes through front and back (pixel row) Matching Fits closer than 1 mm in both x and y at center of tpc A unique time match Histograms At least 30 TPC hits in fit At least 75% of total number of tpc hits in fit Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 8 / 23

Tests from run 347 Run 347 length 60m triggers 4 733 381 V grid 350 V E drift 280 V/cm rotation 17 degree 0 degree threshold 800e Used first 1 000 000 telescope frames: ◮ 461 426 triggers of which 330 925 with matching tracks A drift speed of 75 µ m/ns was assumed Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 9 / 23

ToT-correction s] µ Average ToT [ Before correction After correction 1 0.8 0.6 0.4 0.2 0 0 50 100 150 200 250 Column Differences in odd and even column numbers in ToT Corrected by introducing a factor for each column Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 10 / 23

Time walk correction using ToT × 3 10 Hits Without timewalk correction 600 With timewalk correction 500 400 300 200 100 0 − − − 1.5 1 0.5 0 0.5 1 1.5 x residual [mm] c 1 Timewalk corrected by fitting δ x timewalk = t ToT + t 0 + x 0 Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 11 / 23

Find diffusion from residuals Plot residuals in 2-dimensional histogram × 3 × 3 10 10 240 x-residual [mm] 2 y-residual [mm] 2 220 220 1.5 1.5 200 200 180 1 1 180 160 160 0.5 0.5 140 140 120 0 0 120 100 100 − − 0.5 0.5 80 80 − 1 60 − 1 60 40 40 − 1.5 − 1.5 20 20 − 0 − 0 2 2 4 6 8 10 12 14 16 18 20 4 6 8 10 12 14 16 18 20 Drift distance [mm] Drift distance [mm] Fit gauss to y-slices and put σ in graph from fit to track-residual [mm] from fit to track-residual [mm] 0.3 0.25 0.25 0.2 0.2 0.15 0.15 x y σ σ 0.1 0.1 χ χ 2 2 / ndf / ndf 5592 / 42 5592 / 42 χ χ 2 2 / ndf / ndf 1.28e+04 / 42 1.28e+04 / 42 σ σ ± ± z0 z0 0.1258 0.1258 0.0008 0.0008 ± ± D D 0.07008 0.07008 0.00002 0.00002 ± ± 0.05 0.05 D D 0.07609 0.07609 0.00004 0.00004 ± ± z0 z0 4.7 4.7 0.0 0.0 ± ± z0 z0 5.86 5.86 0.03 0.03 0 0 4 6 8 10 12 14 16 18 20 6 8 10 12 14 16 18 20 z position [mm] z position [mm] � σ 2 Fit z 0 + D 2 ( z − z 0 ) to graph, and get results → Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 12 / 23

Diffusion in pixel plane perpendicular to track from fit to track-residual [mm] 0.25 0.2 0.15 y σ 0.1 χ χ 2 2 / ndf / ndf 1.28e+04 / 42 1.28e+04 / 42 ± ± 0.07008 0.07008 0.00002 0.00002 D D 0.05 ± ± z0 z0 4.7 4.7 0.0 0.0 0 6 8 10 12 14 16 18 20 z position [mm] √ Fix σ z 0 = 0 . 055 / 12 = 0 . 0159 mm D T = 221 µ m / √ cm From laser test D T = 309 µ m / √ cm at 330 V and v drift = 66 . 4 µ m / ns Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 13 / 23

Diffusion in drift direction from fit to track-residual [mm] 0.3 0.25 0.2 0.15 x σ 0.1 χ χ 2 2 / ndf / ndf 5592 / 42 5592 / 42 σ σ ± ± 0.1258 0.1258 0.0008 0.0008 z0 z0 ± ± 0.05 D D 0.07609 0.07609 0.00004 0.00004 ± ± z0 z0 5.86 5.86 0.03 0.03 0 4 6 8 10 12 14 16 18 20 z position [mm] D L = 240 µ m / √ cm From laser test without time walk correction D L = 254 µ m / √ cm at 330 V and v drift = 66 . 4 µ m / ns Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 14 / 23

Hitmap 250 1400 1200 200 1000 150 800 600 100 400 50 200 0 0 0 50 100 150 200 250 Note some defects Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 15 / 23

Deformations in pixel plane perpendicular to track 0.1 Row 250 0.08 0.06 200 0.04 0.02 150 0 − 0.02 100 − 0.04 − 50 0.06 − 0.08 − 0 0.1 0 50 100 150 200 250 Column Deformatiosn in mm Residuals are filled at expected row and column Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 16 / 23

Deformations in drift direction 0.1 Row 250 0.08 0.06 200 0.04 0.02 150 0 − 0.02 100 − 0.04 − 50 0.06 − 0.08 − 0 0.1 0 50 100 150 200 250 Column Deformations in mm Residuals are filled at expected row and column Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 17 / 23

Conclusions Telescope track does not seem te be usable, possible due to material between telescope and Timepix3. A single point was used ToT was corrected and used for a time walk correction The diffusion coefficient fitted from data is D T = 70 µ m / √ mm and D L = 76 µ m / √ mm Deformations in the pixel plane are found to be small ( < 20 µ m ) Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 18 / 23

Next: looking at cross-talk at different voltages 0.07 normalised entries run333 (330 V) 0.06 run340 (335 V) run341 (340 V) 0.05 run342 (345 V) run347 (350 V) 0.04 0.03 0.02 0.01 0 0 50 100 150 200 250 300 350 400 Number of timepix hits Number of hits at different grid-voltages Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 19 / 23

Indication of cut effects status of timepixTrigger × 3 10 300 250 200 150 100 50 0 less than 4 planes hit in telescope All telescope clusters failed fit Telescope and tpc fits do not match More than one cluster in tpc tpc fit leaves or enters on the side Tpc entry already has a matching cluster Less than 20 hits in tpc Telescope fit missed tpc all tpc clusters failed fit Successful Cuts are roughly in order presented before Kees Ligtenberg (Nikhef) Beamtest reconstruction November 20, 2017 20 / 23