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2 Hybrid Pixel Detectors with Active-Edge Sensors for the CLIC Vertex Detector Simon Spannagel on behalf of the CLICdp Collaboration

3 Experimental Conditions at CLIC CLIC beam structure drives design Spacing between bunches: 0.5 ns Trains of 312 bunches, 50 Hz repetition rate Transverse beam size ~nm High bunch density leads to interactions between bunches Large experimental background from γ γ hadrons / e+e(beamstrahlung): ~100 particles/bx within acceptance (at 3 TeV) Mostly in forward direction Timing cuts can reduce impact Low radiation environment Factor 104 lower than at LHC 3

4 The CLIC Vertex Detector Requirements Low material budget: 0.2 % X0 per layer (~200 μm of Si) Low power consumption: forced air flow, power pulsing Fast timing to reduce backgrounds: 10 ns timestamping High spatial resolution: 3 μm single hit resolution Current Design Hybrid pixel detector: 50 μm ASIC, 50 μm sensor 25 μm square pixels Either planar sensors or capacitively coupled active sensors (Talk D. Hynds) 4

5 Performance of Thin Planar Sensors 50μm sensor 700μm Timepix Test beam studies: performance of thin sensors CLIC Timepix3 telescope for reference, 2 μm track resolution Timepix/Timepix3 ASICs, 55 μm pitch High detection efficiency even for 50 μm thin sensor under normal operating conditions Micron/IZM: 100μm sensor on 100μm Timepix 14mm Resolution limited by charge sharing / cluster size Timepix CLICdp work in progress Timepix3 5

6 Active-Edge Sensors Study feasibility of thin sensors with active edge Sensors: Advacam MPW, 50 μm 150 μm thick n-in-p DRIE (Deep Reactive-Ion Etching) Implantation from the side on sensor cut edge extension of backside electrode 6

7 Active-Edge Sensors: Guard Ring Layouts Different guard ring layouts implemented No guard rings, floating guard rings Grounded guard rings, via additional row of bump bonds Edge distance: distance between last n-implant and cut edge No Guard Rings Grounded Guard Ring Floating Guard Ring 7

8 Edge Performance Test beam studies of sensor performance at the edge formance CLIC Timepix3 telescope for reference, 2μm track resolution Timepix3 with active-edge sensors as DUT Tracks from full edge folded into 2x2 pixel matrix Increase statistics ance at the edge: End tracks of pixel close matrix:todashed line edge nsider only the sensor 2 Physical acks are periodically mapped into a 2solid by line 2 cutting edge of sensor: xel cell r illustration, end of the periodic pixel atrix (dashed line) and physical edge of the 0-55 nsor (solid line) are indicated in the lowing plots

9 Active-Edge Sensor, 50μm thickness Without GR and with floating GR: fully efficient up to the physical sensor edge With grounded GR: signal/efficiency loss 9

10 Active-Edge Sensors: TCAD Simulations Different guard ring layouts in Synopsys Sentaurus 2D simulation at implant center Thickness 50μm, edge distance 20μm Field lines end at pixel Most field lines at pixel No charge loss expected Small charge loss Some lines end on ground ring Significant charge loss 10

11 Current Breakdown: Simulation vs Measurements Breakdown at 150V for nogr and gndgr, 50 μm thick Floating GR: smoother potential drop Comparison with measurements not trivial, not very reproducible Influence of additional bond row on floating GR All sensors can be operated well above depletion voltage 11

12 The CLICpix Prototype Readout Chip First prototype ASIC to meet CLIC vertex detector requirements Timepix/Medipix chip family 65 nm CMOS, pitch 25 μm x 25 μm Active matrix of 64 x 64 pixels Simultaneous per-pixel measurement of 4-bit ToT and 4-bit ToA Shutter-based acquisition (optional) on-chip data compression Power pulsing of the pixel matrix 12

13 CLICpix & Thin Planar Sensors Wafer level bump bonding of 25 μm pitch sensors exists No access to ASICs at wafer level (MPW runs) Small sensor (1.6 mm x 1.6 mm), small pitch (25 μm) Single-chip Indium bump bonding process developed at SLAC Test assemblies with CLICpix ASIC and 50 and 200 μm n-in-p sensors Microscope pictures of bump/ubm deposition CLICpix Readout ASIC 28/02/17 200μm n-in-p sensor (Micron) Simon Spannagel - INSTR17 - Silicon Technologies for the CLIC Vertex Detector 13

14 CLICpix & 200 μm Planar Sensors Large spread in quality, bad/missing connection for 2 25% Optimization of bump bonding process ongoing Test beam measurements: 200 μm sensor, threshold 1 ke High detection efficiency, > 99.5 % About 4 μm single point resolution 90 CLICdp work in progress 28/02/17 hits Sr, 200μm sensor Simon Spannagel - INSTR17 - Silicon Technologies for the CLIC Vertex Detector 14

15 CLICpix & 50 μm Planar Sensors Advacam 50 μm thick n-on-p sensor First thin 25 μm pitch assembly Dead: electrically dead Unresponsive: no bump connection Bias only possible up to 5V Issues in bump bonding identified Large dead/unresponsive areas New assemblies to be produced Test beam analysis focuses on responsive regions, analysis of edge region not attempted 28/02/17 Simon Spannagel - INSTR17 - Silicon Technologies for the CLIC Vertex Detector 15

16 CLICpix & 50 μm Planar Sensor: Analysis results Highest efficiency at lowest threshold Efficiency drop with higher thresholds as expected for 50 μm sensor Threshold limited by cross talk in CLICpix ASIC 16

17 CLICpix & 50 μm Planar Sensor: Analysis results 5V bias, 1.3 ke threshold, 50 μm thin sensor DUT performance as expected from 50 μm thin sensor Telescope pointing resolution of 2 μm: in-pixel studies with 25 μm pixels Design target of 3 μm not reached: lacking charge sharing 17

18 The CLICpix2 Prototype Advancement of CLICpix design Same 65 nm CMOS process Larger matrix of 128 x 128 pixels (3.2 x 3.2 mm2 active area) Incr. dynamic range pixels (5b ToT, 8b ToA) Improved noise isolation, removal of cross talk observed in first CLICpix Faster readout with 8/10b encoding Integrated circuits for test pulses and band gap reference First chips from MPW run received Wafer-level access with RD53 submission (end of May) Allows bump deposition on full ASIC wafers One wafer with chips, dummy wafer with top metal 18

19 CLICpix2 (Microscope) Images 19

20 CLICpix2 Readout: The Caribou System Caribou universal readout system: Xilinx FPGA evaluation board Generic periphery board (CaR) Project-specific chip board SoC runs full Linux stack, build using industry-standard tool chain Generic DAQ software: Peary Straight-forward implementation of support for new detectors Parallell operation, e.g. CLICpix2+C3PD (see talk D. Hynds) 20

21 First Test Results: DAC Scans Slow control of chip fully established, (non-standard) SPI protocol used to set and read chip registers Output MUX allows to monitor chip-internal DAC voltages ADC on readout board facilitates automatic DAC scans Car Board 12-bit ADC ADC 12 21

22 First Test Results: DAC scans Example: comparison of simulated/measured test pulse voltage Vta Measured using multimeter (green) and CaR 12-bit ADC (red) Simulation matches well 22

23 First Test Results: DAC scans Current DACs Voltage DACs Measurements and simulations match well for all DACs tested 23

24 First Test Results: Matrix Readout Pixel matrix programmed via shift register, all pixels sequentially First readout of CLICpix2 contains matrix configuration Allows to cross-check matrix programming, readout, data decoding Current status Serial interface established First data frames received from chip Currently verifying matrix programming and data decoding code DAQ Development: Test pulses, control signals for shutter, power pulsing Threshold scans, equalization... 24

25 Summary Proposed CLIC linear e+e- collider poses challenges to vertex Good spatial and temporal resolution, minimum material Comprehensive R&D program for CLIC Vertex Detector Series of prototypes for readout ASIC Studies and test beam performance measurements for thin, planar, small pitch active-edge sensors Next iteration of sensors and ASICs already on the way CLICpix2 in laboratory, DAQ in development More active-edge assemblies to be measured in test beam next week 25

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27 CLIC detector & physics Collaboration 29 institutes 27

28 The Compact Linear Collider Proposed linear collider with novel two-beam acceleration method Achieves high field gradients ~100 MV/m Construction in 3 stages from 380 GeV (11 km) to 3 TeV (50 km) Physics goals: precision SM Higgs, Top and BSM physics Luminosity at 3 TeV: 6x10 cm s m Requirements in CLIC detector driven by Precision required for physics Experimental conditions: Beam-induced background, Beam structure 28

29 CLIC Accelerator Complex 29

30 CLIC Detector Concept 30

31 TCAD Transient Simulation Simulate particle passage with constant charge deposition along path Collect charges at electrodes, record transient currents 31

32 Altered bump mask for Timepix3 ASICs: remove last row of bumps for assemblies with floating or no guard ring avoid shorting the sensor edges. FloatGR 50μm Additional assemblies produced by Advacam NoGR FloatGR 20μm New Active-Edge Assemblies Improved breakdown behavior In test beam next week with Timepix3 ASIC 32