Assembly, construction and testing of the ALICE Silicon Pixel Detector V. Manzari / INFN Bari, Italy for the SPD Project in the ALICE Experiment INFN and Università Bari, Comenius University Bratislava, INFN and Università Catania, CERN Geneva, Institute of Experimental Physics Kosice, INFN Laboratori Nazionali Legnaro (LNL), INFN and Università Kosice, INFN Laboratori Nazionali Legnaro (LNL), INFN and Università Padova, INFN and Università Salerno, INFN and Università Udine

5-7 October V. Manzari - RD05 - Florence Overview  Introduction  Silicon Pixel Detector (SPD) layout  Overview of the SPD Components  SPD modules (Half-staves)  SPD Sectors  Summary and Outlook

5-7 October V. Manzari - RD05 - Florence LHC  Ultrarelativistic nucleus-nucleus collisions - study behaviour of hadronic matter under extreme conditions of heating/compression - investigate confinement/deconfinement, generation of constituent masses  p-p and p-A

5-7 October V. Manzari - RD05 - Florence Radial coverage defined by beampipe and requirements for track-matching with the TPC outer tracking  TPC inner tracking  ITS Inner Tracking System (ITS) R out =43.6 cm 2 strips 2 drifts 2 pixels ITS  array of 6 silicon detector layers Silicon Pixel Detector (SPD) 2 inner layers of hybrid silicon pixel

5-7 October V. Manzari - RD05 - Florence Silicon Pixel Detector  Irradiation at the inner SPD layer: - beam gas interactions - radiation originating from particle production at the interaction point - 10 years standard running (10 8 s pp s Pb-Pb s Ar-Ar) FLUKA simulation TID ≈ 2.5kGy, F ≈ (1MeV n eq )/cm 2  Head-on Pb-Pb collisions at TeV per nucleon: - High multiplicity environment:  80/cm 2 expected track densities at r = 4 cm - Secondary vertexing capability (c, b and hyperon decays) - Track impact parameter resolution r  1.3 GeV/c) - Tracking of low p T particles - Improve momentum resolution

5-7 October V. Manzari - RD05 - Florence Matevz Tadel D 0 decay SPD layer 1SPD layer 2 Background

5-7 October V. Manzari - RD05 - Florence 6 staves/sector (2 inner layer  staggered 4 outer layer  windmill) FE power dissipation/sector: ≈ 150 W Cooling: C 4 F 10 (evaporative), operating temperature ≈ 25°C PHYNOX cooling tubes (1 mm diameter, 40  m thick wall) 2 layers barrel  10 SECTORS (carbon fiber, 200  m thick) SPD layout (I) Carbon Fiber Support Sector (CFSS)

5-7 October V. Manzari - RD05 - Florence Final half-barrels (5 sectors ) SPD layout (II)

5-7 October V. Manzari - RD05 - Florence Half-staves CFSS SPD layout (III) Beam pipe Each stave is built of two HALF-STAVES, read out on the two sides of the barrel, respectively Read out, control, Power and cooling

5-7 October V. Manzari - RD05 - Florence 1200 Readout Chips 240 Sensors 240 Flip-Chip Bonded Ladders 120 Multi-Chip-Modules 120 Bus 120 Half-Staves 2 Barrel Layers …but: Power consumption:~1.5kW Cooling: C 4 F 10 (evaporative) No access w.o. removing ITS and TPC beampipe-SPD: ~5mm Total material budget <1% X 0 per layer Total surface: ~0.24m 2 r= 3.9 cm & 7.6 cm   z= 28.3 cm Operating temperature: 25°C No. of R.O. channels: 9.8 x 10 6 SPD numbers

5-7 October V. Manzari - RD05 - Florence Half-stave components (I) 193 mm long Bonds Readout chips SMD components Carbon fibre support 5-layer bus

5-7 October V. Manzari - RD05 - Florence Mixed signal (analogue, digital) Produced in a commercial 0.25µm CMOS process (6 metal layers, 8’’ wafers) Radiation tolerant design (enclosed gates, guard rings) 8192 pixel cells JTAG FastOR trigger signal 50 µm (r  ) x 425 µm (z) pixel cell ~100 µW/channel ~1000 e - mean threshold (~200 e - RMS) ~110 e - mean noise Readout chip (ALICELHCb1) 13.5 mm 15.8 mm

5-7 October V. Manzari - RD05 - Florence Modular test system based on VME and LabView Test procedure developed at CERN and applied in three different institutes (Catania, CERN, Legnaro) 86 chips/200 mm wafer KGD - Chip Classification Scheme: Class I: Chips for bump bonding Class II: Minor defects Class III: Major defects ~3900 chips tested until today 44 chips Number of class 1 chips/wafer Readout chip - Testing

5-7 October V. Manzari - RD05 - Florence Ladder Pb-Sn Bump Bond VTT/Finland Pb-Sn solder bumps: ~30µm diameter Readout chips: 725  m native thickness thinned to 150  m after bump deposition Sensor: p-in-n matrix, Canberra, 200 µm thick, SiO 2 passivation SEM Pictures Ladder: 1 sensor flip-chip bonded to 5 readout chips bump bonds: 5 x 32 x 256 pixel matrix SPD ladder Flip-chip bonding

5-7 October V. Manzari - RD05 - Florence Testing (on prober): => Limited no. of contacts! Visual inspection Sensor leakage current Full el. test Source-test FO trigger test Ladder classification: Class 1:used for half-stave assembly Class 2: back-up for half-stave assembly Class 3:not useable Ladder -Testing ~ 64% yield (limited statistics!) No. of faulty bond connections/chip Average no. of defects/chip: 4 Max. allowed defects: 82 (1%) Class 1 ladders for HS-assembly: - Leakage current<2µA - Full electrical functionality - <1% defect pixels /chip

5-7 October V. Manzari - RD05 - Florence Analog Pilot: Reference bias ADC (T, V and I monitor) Multi Chip Module (MCM): ALICE1LHCb chip Analog Pilot (AP) Digital Pilot (DP) GOL (Giga-bit optical link) Optical Module (OM) Outogoing Data Stream Trigger and JTAG configuration data LHC 40 MHz clock AP DP GOL Digital Pilot: Timing, Control and Readout Optical Module 1 laser and 2 pin diode In Si-case 1.2 x 17 x 5.5 mm 3 Multi Chip Module (MCM) OM

5-7 October V. Manzari - RD05 - Florence 5 layer Al-Kapton flex 240  m thick (->material budget) Wire bonds to the readout chips+MCM Provides data -, control- and power-lines between readout chips and MCM Prototypes with Cu (signals) and Al (GND-VDD) planes First batches of All-Aluminium bus produced and currently under test Multilayer bus Bus Chip  MCM and multilayer bus are tested before they are used for half-stave assembly

5-7 October V. Manzari - RD05 - Florence Half-stave – Assembly (I) Assembly procedure developed and carried out in Bari: Mitutoyo Coordinate Measuring Machine equipped with jigs for SPD HS assembly

5-7 October V. Manzari - RD05 - Florence Grounding foil Gluing ladders + MCM Half-stave – Assembly (II) Glue dispensing Gluing bus + extender

5-7 October V. Manzari - RD05 - Florence MCM Half-stave – Assembly (III) Grounding foil Ladder 1 Ladder 2 MCM + extender 5-layer bus + extender

5-7 October V. Manzari - RD05 - Florence Ecobond 45 SMD components Grounding foil Bump Bonding Polyamide Aluminium + Ni & Au deposition Readout chip Sensor GND layer VDD layer Pads 310 μm 2030 μm 500 μm 1000 μm 460 μm Fast Or wire 550 μm ~1200 Wire bonds/half-stave 25µm diameter wire Bonding pads on the bus: 80 x 300µm 2 Step height: 40-60µm Half-stave – Wire bonding Extender 10 Chip ……. Connections between 5-layer bus and ladders + MCM Bonder machine: F&K Delvotec 6400 Wire Bonding MCM Wire Bonding FE chip MCM Multilayer bus Grounding Foil FE chip Sensor GND VDD Layer segnali

5-7 October V. Manzari - RD05 - Florence Half-stave – Testing Cooling system (Peltier cells) X-Y movements  microscope and source ( 90 Sr) Half-stave

5-7 October V. Manzari - RD05 - Florence Half-staves transport Fully qualified half-staves are transported to Legnaro for the mounting on the Carbon Fiber (CF) sectors

5-7 October V. Manzari - RD05 - Florence CF sector mounting (I) Half-staves mounting on the carbon fiber sectors: procedure developed and carried out in Padova/Legnaro Johansson Coordinate Measuring Machine equipped with jigs for SPD Sector mounting

5-7 October V. Manzari - RD05 - Florence Optical connections Power supply HS CF sector mounting (II) Carbon fiber support sector Wire – bonding Half-Stave CF clip Critical aspects in the HS mounting:

5-7 October V. Manzari - RD05 - Florence Thermal grease underneath the chips (coupling to cooling tubes) UV-glue drops and CF clips to fix the HS position Thermal grease UV glue CF clip Cooling tube CF sector mounting (III)

5-7 October V. Manzari - RD05 - Florence 1st SPD Sector 1st SPD sector fully equipped with 12 half-staves Integration and test with cooling system, DCS, readout electronics and power supply is starting 1st sector

5-7 October V. Manzari - RD05 - Florence The SPD constitutes the two innermost layers of the ALICE inner tracker - In total 9.8 M pixel cells of 50  m (r  ) x 425  m (z). - The SPD will allow ALICE to access heavy flavour signals in ultra-relativistic nucleus-nucleus collisions. Severe constraints in material budget and geometry. Specific technology developments (FE chip, multi-layer bus, MCM, evaporative cooling) and extensive tests of the SPD components completed - Production of thin ladders (200  m sensor  m FE chips), MCMs and all-Aluminium buses is under way The Half-stave and Sector assembly procedures have been developed. - Half-stave production ongoing: throughput 4 HS/week - 1 st SPD Sector fully equipped with HSs Summary

5-7 October V. Manzari - RD05 - Florence Spatial Precision and Efficiency  Single chip assemblies have been tested at CERN SPS: - in year 2002  300 GeV/c proton beam - in year 2003  120 GeV/c proton/pion beam  Tracking error estimated to be  track  10  m in both x and y coordinates  Spatial precision:  Efficiency: in all cases > 99% Summary: Results from data analysis of 2002 & 2003 beam tests show that spatial resolution and efficiency are in very good agreement with design targets and satisfy the ALICE requirements.

5-7 October V. Manzari - RD05 - Florence Outlook  SPD integration will take place at CERN in the Divisional Silicon Facility.  Very challenging times ahead: - tight construction schedule in order to be ready for 1st beam - SPD installation in ALICE  end November 2006