1. J.R. Carter SCT Barrel Module PAR - Overview 1 14th May 2003 ATLAS SCT BARREL MODULE PAR COMPONENTS AND PRODUCTION OVERVIEW Janet Carter, Cambridge TOPICS: 1. Barrel Module Requirements 2.Module Component Production 3.Module Assembly Clusters 4.Module Specifications and Categories 5.Module QA Steps and Common Issues 6.Production Schedule 7.Summary

2. J.R. Carter SCT Barrel Module PAR - Overview 2 14th May 2003 The Barrel Module 2112 Identical Barrel Modules required for SCT mounted on 4 Barrels (B3, B4, B5, B6) Bridged wrap-around hybrid – copper-polyimide flex glued on carbon-carbon substrate 4 single-sided p-in-n ac-coupled silicon microstrip sensors, 80 µm pitch, mounted back-to-back, 40 mrad stereo rotation angle 12 128-channel ABCD3TA binary readout ASICs Thermo-mechanical baseboard - encapsulated thermalised pyrolitic graphite with fused BeO facings

3. J.R. Carter SCT Barrel Module PAR - Overview 3 14th May 2003 Module Requirements Detailed in Barrel Module FDR, May 2001: SCT-BM-FDR-4 (http://atlas.web.cern.ch/Atlas/GROUPS/INNER_DETECTOR/SCT/module/SCTbarrelmod.html )http://atlas.web.cern.ch/Atlas/GROUPS/INNER_DETECTOR/SCT/module/SCTbarrelmod.html Summary of Principal Module Requirements:  MIP Detection efficiency >99% with noise occupancy ≤ 5×10 -4  Intrinsic r-φ point resolution per single-side measurement of 23 µm (80 µm pitch sensor strip)  Giving 17 µm precision in r-φ co-ordinate and 500 µm in z from back-to-back sensor pair with stereo rotation angle of 40 mrad  Precise mechanical assembly to simplify digitisation and alignment in ATLAS  Low mass - <1.2% X 0 per module, averaged over sensor area  1.17% X 0 achieved  Electrical performance maintained up to radiation levels of 2×10 14 n eq cm -2 (barrel 3 with safety factor)  Verified through proton (CERN PS) and neutron (Llublyana) irradiation and lab and test beam studies (sensors, ASICs, modules)

4. J.R. Carter SCT Barrel Module PAR - Overview 4 14th May 2003 Summary of Principal Module Requirements (continued):  Cold operation in ATLAS (cooling pipes ~ -20 o C) – module must routinely withstand thermal cycling between -25 o C and +30 o C  Tested by thermal cycling in module QA  Module safe against thermal runaway of sensors after irradiation in ATLAS  Thermal designs of baseboard, hybrid and cooling block – thermal simulations and tests with irradiated modules

5. J.R. Carter SCT Barrel Module PAR - Overview 5 14th May 2003 Module Component Production Hybrids – in production in Japanese industry – talk by S. Terada Baseboards – in production by collaboration at CERN – talk by A. Carter Glues – purchased centrally and distributed to module assembly sites Silicon Sensors and ASICs – status briefly summarised here: All SCT barrel sensors manufactured by Hamamatsu Photonics, Japan  Identical detectors for all modules: 64mm×63.6mm×285 µm thick  Single-sided, ac-coupled, 768 readout strips at 80 µm pitch Milestones – all achieved, on schedule:  Sensor FDR: April 1999  Sensor PRR following evaluation of pre-series: August 2000  Start of series deliveries: January 2001  Delivery (including purchase options) completed: May 2003 QA completed by collaboration (pre-irradiation and sampling after 3×10 14 p.cm -2 24 GeV/c proton irradiation at CERN PS) Sensor quality is excellent Silicon Microstrip Sensors

6. J.R. Carter SCT Barrel Module PAR - Overview 6 14th May 2003 Series Deliveries (Barrel + Endcap) Purchase options added Contract Ordered (including purchase options) Delivered Japan60005913 Norway1950 UK2750 Total10,70010,613 Barrel 99% Complete on 1 st May 2003 Pre-Irradiation:  All quantities within specification  Very low leakage currents Typically <200 nA at 500V bias at 20 o C  >99.9% good readout strips Initial current at 350V bias (20 o C) Number of Strip defects

7. J.R. Carter SCT Barrel Module PAR - Overview 7 14th May 2003 Post-Irradiation:  Within specification for operation at ~400V bias after 10 years of LHC Points to note for module construction concerning high bias voltages:  The edges of the sensors are at the back-plane voltage  Great care must be taken to avoid conducting debris shorting to grounded areas – eg bond wires, openings in sensor passivation in guard rings, bond pads etc  Module production and assembly to barrels must be a clean process  On Barrels 3 and 4, modules must be tested to 500V bias during assembly and commissioning at CERN to ensure there are no HV shorts that would prevent final post-irradiation HV operation  So I-V of modules are tested up to 500V in assembly QA (even though initial modules will operate at <200V bias)

8. J.R. Carter SCT Barrel Module PAR - Overview 8 14th May 2003 Pre-irradiation sensor ‘microdischarge’  A small fraction ( ≤ 2%) of sensors show ‘microdischarge’ (impact ionisation) pre-irradiation between 350V and 500V bias  Rapid current rise with bias voltage, but falls to normal levels with short time-constant (~30 mins) if bias maintained  Not a problem for module operation in ATLAS:  Disappears after irradiation and type-inversion - field configuration changed:  But will not use ‘mirodischarge’ modules for the inner barrels 3 and 4 as they complicate initial HV tests up to 500V during macro-assembly and commissioning Example of smooth, normal I-V curves of ‘microdischarge’ detectors up to 500 V bias after irradiation to 3×10 14 p cm -2

9. J.R. Carter SCT Barrel Module PAR - Overview 9 14th May 2003 Front-End ASICs n ABCD3TA ASIC u DMILL technology, fabricated by Atmel u Single-strip threshold binary readout u Threshold trimming for each channel n Performance meets requirements both pre- and post-irradiation, with ~1fC binary threshold n Series production released in July 2001 following PRR u ~87% of SCT requirement for perfect ASICs now delivered and die identified after wafer testing u But Atmel may not deliver any more before the DMILL line is stopped n The SCT will use an ASIC with 1 bad channel on each module as necessary to make up the shortfall u Should have a negligible effect on barrel performance Deliveries stopped ASIC Statistics Lots delivered50 Accepted wafers795 Accepted wafer yield25.9% Tested wafers rejected24.0% Accepted perfect chips52,695 % of total requirement87.5% Wafers left to test0

10. J.R. Carter SCT Barrel Module PAR - Overview 10 14th May 2003 Module Assembly Clusters 4 Barrel Clusters for module assembly:  Japan, Scandinavia, UK, US – reports from each on progress to-date Clusters have developed different jigging and assembly techniques  Each builds to the same module specification  Site qualification process following FDR/PRR in May 2001 with documented requirements and module exchange before series module assembly can get fully underway ClusterSite Qualification Date Number of modules to deliver to macro- assembly sites (Oxford, KEK) JapanDecember 2001800 ScandinaviaNot yet400 UKJune 2002550 USApril 2003480

11. J.R. Carter SCT Barrel Module PAR - Overview 11 14th May 2003 Summary of Principal Module Build Specifications: Detailed in Barrel Module FDR, May 2001: SCT-BM-FDR-7 (http://atlas.web.cern.ch/Atlas/GROUPS/INNER_DETECTOR/SCT/module/SCTbarrelmod.html )http://atlas.web.cern.ch/Atlas/GROUPS/INNER_DETECTOR/SCT/module/SCTbarrelmod.html Electrical Performance  <1% bad readout strips at 1fC binary threshold (noisy, dead, part- bonded, untrimmed, pipeline errors etc).  Verified through a Characterisation Sequence test using custom SCT VME readout, prototype SCT voltage supplies and standardised DAQ and analysis code (SCTDAQ)  Module sensor leakage current < (sum of individual sensors + 4 µA) up to 500V bias at 20 o C  Stable performance during 24 hour cold operation (hybrid at ~0 o C) All Modules classed for use in ATLAS satisfy the full electrical specification Module Specifications and Categories

12. J.R. Carter SCT Barrel Module PAR - Overview 12 14th May 2003 Mechanical Specifications Principal in-plane parameters (further parameters define the hybrid position and angle) (y is perpendicular to the sensor strips to within half the stereo angle) In-Plane Parameter Design Value ‘Good’ Module Tolerance ‘Pass’ Module Tolerance Baseboard dowel mounting hole in x, mhx [µm]-6500±30±40 Baseboard dowel mounting hole in y, mhy [µm]-37500±30±40 Baseboard dowel mounting slot in x, msx [µm]38500±100±140 Baseboard dowel mounting slot in y, msy [µm]-37500±30±40 Mid-point of pair of front sensors in x, midxf [µm]0±10 Mid-point of pair of back sensors in y, midyf [µm]0±5±8 Separation of centres of sensors; front pair, sepf; back pair sepb [µm] 64090±10±20 Rotation angles of the 4 sensors, a1, a3, a3, a4 [mrad]0±0.13 Half stereo angle between the front and back sensor pairs, stereo [mrad] -20±0.13 The category ‘Good’ satisfies the agreed specification The category ‘Pass’ is an extension to cover measurement error and the tails of the observed distributions Both ‘Good’ and ‘Pass’ modules will be used in ATLAS

13. J.R. Carter SCT Barrel Module PAR - Overview 13 14th May 2003 Out-of-Plane Parameter Design Value ‘Good’ Module Tolerance ‘Pass’ Module Tolerance Maximum deviation of lower sensor from module plane, maxZlower [mm] 0-0.2 Maximum deviation of upper sensor from module plane, maxZupper [mm] 00.2 Module thickness [mm]1.15±0.1 Maximum deviation of lower sensor from common module profile, optimalmaxZerrorlower [mm] 00.050.07 Maximum deviation of upper sensor from common module profile, optimalmaxZerrorupper [mm] 00.050.07 RMS deviation of lower sensor from common module profile, optimalRMSZerrorlower [mm] 00.025 RMS deviation of upper sensor from common module profile, optimalRMSZerrorupper [mm] 00.025 Lower BeO cooling facing angle perpendicular to mounting line, b [mrad] (module cooling contact issue) 0±3±5 Lower BeO cooling facing angle parallel to mounting line, a [mrad]0±0.5 Lower BeO cooling facing concavity along the mounting line, loCoolingFacingConcavity [mm] 0±0.03 Maximum thickness of module at surface of large capacitors on hybrid, capMaxThickness [mm] (clearance issue) 5.786.44 Principal out-of-plane Parameters  Detector surfaces compared with a standard shape  ‘Good’ and ‘Pass’ categories again defined

14. J.R. Carter SCT Barrel Module PAR - Overview 14 14th May 2003 Barrel Module Categories  Each produced module is assigned to one of the following categories:  From component availability and schedule requirements, ~90% of modules started in assembly need to be suitable for use in ATLAS CategoryDescription GoodSatisfies all electrical and ‘good’ mechanical specifications. Pass In ‘pass’ grade for 1 or more mechanical parameters. Satisfies all electrical specifications. Hold Outside ‘pass’ grade for 1 or more mechanical parameters and/or does not satisfy all electrical specifications. Such a module is stopped in production and stored. Fail Could never be used in ATLAS (damage, gross errors). Rework Rework is needed before the module could be usable.

15. J.R. Carter SCT Barrel Module PAR - Overview 15 14th May 2003 Module QA Steps and Common Issues Basic steps in module assembly (with small variations between Clusters): StepQA after step 1. Load 12 ASICs on hybrid  Electrical tests warm and cold 2. Glue 4 sensors to baseboard  In-plane metrology 3. Wrap hybrid around and glue to baseboard-sensor sandwich 4. Wire-bond module  Metrology (in-plane and out-of-plane) following thermal cycling  Electrical characterisation warm  Long-term (24 hr) electrical test cold  Visual inspection

16. J.R. Carter SCT Barrel Module PAR - Overview 16 14th May 2003 A Common Electrical Issue: s-curves Noise-occupancy s-curves are part of module electrical characterisation  These are occupancy vs threshold for no injected charge Normally they are smooth curves: picture here

17. J.R. Carter SCT Barrel Module PAR - Overview 17 14th May 2003 But coherent effects can build up between ASICs when digital activity is high and produce s-curve distortions at thresholds << 1fC  A severe example: picture here

18. J.R. Carter SCT Barrel Module PAR - Overview 18 14th May 2003 Barrel Clusters have recently been studying all their available data because a high fraction (of the small number) of series modules completed by Scandinavia have severely distorted s-curves  Has caused a delay in Scand site qualification, in case of any association with the hybrid mounting technique used by Scand – they are now proceeding cautiously with a new method But s-curve distortions are seen in varying degrees by all Clusters  An on-going study to look for correlations and differences between Clusters Does it matter?  We think not, provided the distortions are well below (<0.3 fC) the operating threshold of 1fC – which they are  Noise Occupancy of module at 1fC is not affected  Effect reduces with irradiation  Has not to-date caused problems in system test operation  The properties after irradiation and system operation will be further tested this summer using modules with the most severely distorted s-curves

19. J.R. Carter SCT Barrel Module PAR - Overview 19 14th May 2003 Production Schedule SCT Schedule requirements for macro-assembly imply: ******I have made up these dates, which are later than the schedule******* There are further constraints on selecting the modules with the most robust high bias voltage characteristics for barrels 3 and 4 Nevertheless, sufficient modules should be available in time for the required completion of the first barrel - B3 BarrelNumber of Modules to deliver From Clusters Delivery to be completed by B3404AllDecember 2003 B6706AllMarch 2004 B5605AllMay 2004 B4504JapanJune 2004

20. J.R. Carter SCT Barrel Module PAR - Overview 20 14th May 2003 Summary Sensors are in-hand and of very good quality Problems with the end of ASIC delivery, but 1-bad channel chips can be used to make up the difference Module assembly underway – now x% of total ‘Good’ + ‘ Pass’ requirement completed Site qualification of the Scandinavian cluster is an urgent priority Integrated assembly yield is still lower than the 90% target for all but the Japanese cluster (to be seen from the Cluster presentations) Overall quality of modules is good – s-curves need careful monitoring and some more study