Preliminary results from Quad test beam Kees Ligtenberg LC-TPC Colloboration meeting January 7, 2019 Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 1 / 14
Table of Contents Introduction 1 Synchronization issues 2 Quad results 3 Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 1 / 14
Introduction Quad is a module consisting of 4 Timepix3 chips, with all services under the active area Quad detector is put inside a test box with guards and field shaping, filled with T2K gas See also introduction talk by Peter Kluit Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 2 / 14
Test beam setup 2 . 5 GeV electrons provided by the ELSA facility (Bonn) at a 10 kHz rate Events are triggered by a scintillating plane The telescope consist of 6 mimosa planes with 18 . 4 µ m × 18 . 4 µ m sized pixels Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 3 / 14
Timepix readout procedure Timepix readout procedure The Timepix3 registers the fine time of a hit and stores it near the pixel to be read out. 4 Timepix3 chips are connected with one 160 Mb/s link to the SPIDR each ◮ 12 links with a maximum speed of 640 Mb/s per link are available The SPIDR boards adds a course time stamp (409.6 µ s per tick) to each hit and transmits it to the DAQ PC. Hits that arrive too late at the SPIDR board receive the wrong course time Because the link speed was not fast enough for the rates, a maximum of 1.3 MHits/s was read out per chip Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 4 / 14
Synchronization issues Entries quad chip 0 (RMS = 54.26) quad chip 1 (RMS = 55.52) × 3 300 10 quad chip 2 (RMS = 80.85) quad chip 3 (RMS = 53.45) Entries 180 single chip (RMS=180 for 20 < N < 1000) hits 160 250 140 200 120 100 150 80 100 60 40 50 20 0 0 20 40 60 80 100 120 140 160 180 200 100 200 300 400 500 600 700 800 900 1000 µ Shifted time [409.6 s] N hits Hits after selection: some hits are not read The number of hits per 409 . 6 µ s does hardly out until after 160 cycles of 409 . 6 µ s fluctuate (Teal represents the 2017 single chip) The solution is to stack hits from up to 200 cycles after the original trigger Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 5 / 14
Selections Use runs 668, 672, and 676 (center, right, left respectively): V drift = 400 V / cm, which is near the maximum drift velocity because of a water vapor concentration of around 4000 ppm V Grid = 330 V Threshold at ∼ 550 e (55 DAC counts above noise) Selection − 500 ns < t hit − t trigger < 500 ns Hit ToT > 0 . 10 µ s Reject outliers ( r x < 1 . 5 mm , r z < 3 mm ) N hits > 20 ( N r x < 1 . 5mm / N r x < 5mm ) > 0 . 8 x hit − x track < 0 . 3 mm Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 6 / 14
Hit maps Run 668 Run 672 Run 676 Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 7 / 14
Drift velocity Because of water vapor content (0.6%), the drift velocity is expected to be slower than normally for a T2K gas The measured drift speed (55 µ m / ns) is slightly smaller than expected for this water vapor concentration (60 µ m / ns) v drift [µ m/ns ] 90 80 70 60 50 40 30 20 10 6789 2 3 4 5 6789 2 3 4 5 6789 102 103 E [ V/cm ] Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 8 / 14
Time walk correction? Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 9 / 14
Resolution in the transverse direction 0.5 from fit to track-residual [mm] 0.45 0.4 0.35 0.3 0.25 0.2 µ D 464 m/ cm x 0.15 − z0 1.08 mm 0.1 x χ σ 2 / ndf 22105 / 96 0.05 0 0 2 4 6 8 10 z-position [mm] � σ 2 x 0 + D 2 σ x = T ( z − z 0 ) Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 10 / 14
Resolution in the drift direction 0.8 from fit to track-residual [mm] µ µ 0.10 s < ToT < 0.30 s (10%) 0.7 µ ToT > 0.30 s (89%) 0.6 0.5 0.4 0.3 µ D 187 µ m/ cm D 187 m/ cm 0.2 L σ z µ σ 264 µ m z0 264 m z0 − z z0 1.08 mm σ 0.1 χ − 2 / ndf z0 6023 / 97 1.08 mm 0 0 2 4 6 8 z-position [mm] � σ 2 z 0 + D 2 σ z = L ( z − z 0 ) Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 11 / 14
Deformations in the pixel plane 25 0.1 y[mm] mean x-residual [mm] 0.08 20 0.06 15 0.04 Calculate the mean x-residual 10 0.02 per 4 × 4 pixels 0 5 Alignment problem in the left two chips will be looked at before − 0.02 0 Thursday − 0.04 − 5 − 0.06 − 10 − 0.08 − 0.1 0 5 10 15 20 25 x [mm] Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 12 / 14
Deformations after correction To be added before Thursday Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 13 / 14
Conclusions A good set of data with the Quad was taken using 2 . 5 GeV electrons A synchronization problem was identified, and a work-around is in place The hit resolution will be further investigated In the first diagrams, systematic deformations are small Analysis is well under way Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 14 / 14
Deformations in the drift direction without per column calibration 0.1 25 y[mm] mean z-residual [mm] 0.08 20 0.06 15 0.04 10 0.02 0 5 − 0.02 0 − 0.04 − 5 − 0.06 − 10 − 0.08 − 0.1 0 5 10 15 20 25 x [mm] Kees Ligtenberg (Nikhef) Results from Quad test beam January 7, 2019 15 / 14
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