Abraham Gallas V Jornadas sobre la participación española en futuros aceleradores lineales Timepix Pixel Sensors Tracking & Timestamping for ILC

Outline  ILC environment and assumptions  Detector design rationale  ASIC (Timepix)  Sensor thinning  Low mass bump bonding  Test beams with Timepix  Next steps 26/10/10Abraham Gallas 2

ILC in a nutshell 26/10/10Abraham Gallas 3 e + e - linear collider Center of mass energy range GeV Peak luminosity 2 x cm -2 s -1 Bunch timing: 5 pulses per second (5 Hz) 1260, 2625, 5340 bunches per pulse separated by 180, 369, 500 ns power pulsing readout speed 14 mrad crossing angle Background: small bunches create beamstrahlung → pairs Hit density (#/mm2/BX)

Forward tracking detector 26/10/10Abraham Gallas 4  Relevant physics processes with particles emitted at small  : mostly e -,  t, b- and c-jets  ILD's Forward Tracking Disks  The forward region 6° <  < 30°: 0.1 rad <  < 0.45 rad 0.9 < cos  < < |  | < 3.

Detector design rationale  25x25  m pixel sensor instrumented with ROC derived from current Timepix (Timepix2-Timepix3)  Both ToT and ToA modes running simultaneously in each pixel  Time resolution of ∼ 10 ns or better (Timepix2 > 1.5ns (25ns/16)) allowing time stamping (bunch tagging)  Full readout between pulses (5Hz) or every 100BX  Power cycling leading to a 70% reduction on the time the ROC is ON (Timepix2 ∼ 45  W/pixel). 26/10/10Abraham Gallas 5

The Medipix Chips A philosophy of functionality built into the pixel matrix allows complex behavior with a minimal inactive region 55  m square pixel matrix 256 by side buttable Configurable ‘shutter’ allows many different applications bipolar (h + and e - ) Silicon, CdZnTe, CdTe, GaAs, Amorphous Silicon, 3D, Gas Amplification, Microchannel Plates etc…

Timepix (2006) sensor Analogue amplification Digital processing Read-out ASIC Timepix design requestedand funded by EUDET collaboration Conventional Medipix2 counting mode remains. Addition of a clock up to 100MHz allows two new modes. Time over Threshold Time of Arrival Pixels can be individually programmed into one of these three modes Time over Threshold Threshold Time Over Threshold counts to the falling edge of the pulse Threshold Time of Arrival Time of Arrival counts to the end of the Shutter

Development history and future 26/10/10Abraham Gallas 8 Medipix1 1  m SCAMOS 64 by 64 pixels Photon Counting Demonstrator (1997) Medipix2 250nm IBM CMOS, 256 by  m pixels Full photon counting (2002) Analogue (ToT) and Time Stamping (ToA) (2006) Timepix 130nm IBM CMOS Photon Counting, Spectroscopic, Charge Summing, Continuous Readout (2009) Fast front end, Simultaneous ToT and ToA (2011) Timepix2 Medipix3 VELOpix Timepix3 CLICpix 130nm/90nm/65nm Future LHCb readout – Data driven 40MHz ToT 12Gb/s per chip (2013) 130nm/90nm/65nm Future Hybrid Pixel Time tagging layer for the LCD project (20??)

Timepix2 Main Requirements Pixel size55 µm x 55 µm Pixel matrix array256 x 256 Sparse readoutYES PC, TOA or TOT recorded simultaneously YES (2 at a time) Minimum detectable charge≤ 500 e- TOA resolution>1.5ns (25ns/16) 4bits (Gossipo3 style) Peaking time< 25 ns TOT resolution<5% channel to channel spread TechnologyIBM 130nm DM Power consumption<1.5W/cm 2 (~45 V Target floorplan3 sides buttable and minimum periphery TSVs possibilityYES. Multi-dicing scheme as Medipix3 9 Lots of different applications → Very demanding specs ! XAVIER LLOPART– CERN PH-ESE

Sensor thinning 26/10/10Abraham Gallas 10 Timepix on SOI 150  m  Collaboration with CNM to thin 2D-pixel (55x55 μm) sensor from 300 μm down to 200, 150, 100 μm, p-on-n & n-on-p  Read out with TimePix ASIC  Goal: Measure resolution, efficiency, … thin sensor Minimal guard ring design. Production of module/ladder with 3 ASICs 55 Fe

Low mass bump bonding 26/10/10Abraham Gallas 11  Pixel detectors consist of a sensor chip and ROC which are connected with flip chip bumps.  One of the current technologies (FC µ-bump):  20-30μm (SnPb, SnAgCu, SnAg, … )  40-… μm pixel pitch  For 55(25) μm pixel size adds 0.019(0.091) % X o  Other technologies that can reduce considerably the material budget:  Solid-Liquid-Inter-Diffusion (SLID) Soldering:  55 μm pixel sensor: % X o  25 μm pixel sensor: % X o  Carbon Nano Fiber (CNF) Interconnections (R&D stage):  55 μm pixel sensor: % X o  25 μm pixel sensor: % X o

In SLID tin, indium or other metals with low melting point (MP) are capped on high melting point (MP) pads, because: 1.Creation of intermetallic compounds (IMC) with the pad metal. 2.High planarity requirements of metal-metal bonding (e.g., Cu-Cu) are compensated. Solid-Liquid-Inter-Diffusion (SLID) soldering, AKA Transient-Liquid-Phase (TLP). Thin layer of solder turns completely into IMC  ultra thin metallic joints! After the first reflow the MP increases significantly and becomes thermally very stable. Cu-Sn-Cu structure is the most commonly used, and with an optimized process Sn transforms to Cu3Sn in some minutes. Solid-Liquid-Inter-Diffusion (SLID) Soldering Beginning: Thick Cu pads and < 5 µm of Sn. Bonding at 270 – 300 ̊ C. Step 1 Sn reacts with Cu and creates IMC’s. Cu6Sn5 phase grows in big scallops. Step 2: Cross-hatched Cu6Sn5 phase consumes the Sn aggressively. Cu3Sn phase grows on at Cu interfaces. Step 3: All Sn has been transformed to IMC’s. Cu3Sn is taking over Cu6Sn5 and grows at the expense of Cu6Sn5 and Cu. Step 4: After long heating, the ductile Cu3Sn expands over the whole area and forms the a thin joint. SAMI VAEHAENEN – CERN PH-ESE

Carbon Nano Fiber Interconnections 26/10/10Abraham Gallas 13 CERN has started a small project with Smoltek (Gothenburg, Sweden) to develop fine-pitch CNF interconnection technique for pixel chips. Goal is set at growing 5 µm – 10 µm long fibres on chips and joining them together. Electrical contacts will be tested with/without metal contacts. CNF’s would be ultra-low mass interconnections. Technology has prospects to be ultra-fine pitch capable. High planarity of ROC and sensor is required. First CNF forests have been deposited on CERN test vehicle chips. Development plan has been made to improve the patterning resolution and to develop suitable flip chip processes. SAMI VAEHAENEN – CERN PH-ESE

Timepix Testbeams 26/10/10Abraham Gallas 14 Six Testbeams with Timepix in 2009 and 2010

2009 Testbeam - Proving Timepix 26/10/10Abraham Gallas 15 Timepix had not been used at all in a particle tracking application We took the opportunity to run parasitically in three beam periods Tested a 300  m standard silicon Timepix assembly and a DS3D assembly Main Measurements: Resolution vs. Angle Resolution vs. Threshold Resolution vs. Silicon Bias Efficiency vs. Threshold Efficiency vs. Bias Timewalk

Three Testbeams in 2009 June 2009 : Medipix Testbeam 3 days to demonstrate tracking July 2009 : CMS SiBit beam period Two weeks – parasitic Timepix Telescope 2 Timepix 2 Medipix ~perpendicular No DUT 2 Timepix 4 Medipix ~perpendicular 300μm and 3D DUTs Manual angle adjustment

August 2009 Timepix Telescope 4 Timepix, 2 Medipix planes in telescope Symmetric positioning of planes around DUT Telescope planes mounted at 9 ° around x & y to boost resolution DUT position and angle controlled remotely by stepper motors 2.3  m Track Reconstruction Error ~100Hz track rate 1 frame per second ~100,000 tracks per measurement point ~1.5 hours per point in SPS North Area

55μm 300μ m 0o0o Angled Planes to Boost Resolution Hits that only affect one pixel have limited resolution (30μm region in 55μm pixel) Tilting the sensor means all tracks charge share and use the ToT information in centroid, CoG calculations 0 o ~10μm resolution 9 o ~4.2μm resolution Indicative Timepix events 55μm 300μm 9o9o

2009 Results – Resolution Vs Track Angle Resolution result from 2009 testbeam demonstrating resolution of a Timepix assembly and the performance of the telescope Operating point of Telescope planes

Eta distributions 26/10/10Abraham Gallas 20 Uncorrected 0 o incidence 5 o incidence 8 o incidence 18 o incidence 1 pixel wide clusters 2 pixel wide clusters 3 pixel wide clusters Corrected

2010 Testbeam Activity  3 beam periods as main user  Added Time Tagging System  May USB2 readout 300  m Timepix and PR01 fine pitch microstrip sensor (40μm)  June USB2 readout 150  m Timepix and PR01 Strip  August RELAXD readout 3D irradiated Timepix, FZ, MCZ, BCB strip, 150  m Timepix and 300  m Timepix  Not all data analysed yet so not too many results to show

2010 Timepix Telescope 6 pixel telescope planes angled in 2 dimensions to optimise resolution Device Under Test moved and rotated via remote controlled stepper motor Fine pitch strip detector with fast electronics LHC readout

2010 Telescope in Timepix DUT Configuration Timepix ToT Tracking Timepix DUT Scintillators to set shutter length to e.g. 100 tracks beam Shutter Generator In this configuration the telescope was optimized for running with a Timepix DUT The USB2 readout allowed a 7 frame per second readout rate (700Hz track rate) The all angled six Timepix telescope gives a ~2.0μm Track Extrapolation Error

Time Resolution for LHC readouts  Asynchronous SPS beam not suited to LHC systems designed for 25ns bunch structure  Implemented a TDC which with Timepix ToA mode gives us ~1ns per track time stamping  Able to provide and record synchronised triggers to 40MHz readout systems (TELL1)  Allows software reconstruction and analysis of asynchronous tracks PR01 DUT Timepix ToT Tracking Timepix ToA Track Time Tagging Plane ~100ns Scintillator Coincidence and TDC ~1ns Logic + TDC Synchronized Trigger Telescope in Time Tagging configuration for LHCb Sensor Readout beam

150 μm Sensor Results With a 150μm sensor the optimum resolution point is at twice the angle of a 300μm The higher data rate allows a significant number of measurements to be taken

RELAXD Readout  High Resolution Large Area X-Ray Detector  RELAXD readout from NIKHEF  50 frames per second over gigabit Ethernet

August 2010 Telescope – Timepix DUT Cooled DUT Timepix ToT Tracking RELAXD interface RELAXD system allowed 55 frames per second readout (~2,500 tracks per second) Each 100,000 point measurement now takes 4 minutes Eight angled Timepix tracking planes gives a ~1.67um Track Extrapolation Error Closer tacking planes reduce multiple scattering effects

Cooling system 26/10/10Abraham Gallas 28 To operate irradiated assemblies its necessary to cool the sensor to below 0 o C This system achieved a steady temperature of ~-5 o C Water Block Sensor+ROC and Pyrolytic Graphite 80W Peltier

Telescope Comparisons 26/10/10Abraham Gallas 29 TelescopePixelResolutionTime TagRate Timepix  m2.3  m 100ns100Hz Timepix 2010 (May) 55  m2.0  m ~1ns350Hz Timepix 2010 (Aug) 55  m1.7  m ~1ns2.8kHz EUDET (Low res) 18  m~2  m 100us990Hz EUDET (High res) 10  m~1  m -300Hz? EUDET. Telescope

Next steps  Module0 construction (3-4 ROC)  Minimal guard ring design  Thinning of ROC (50 μm)  Thinning of sensor to 80 μm  Bump bonding thin sensor on thin ROC  Support structures (CVD) 26/10/10Abraham Gallas 30