CMS Strip Tracker R&D

Transcription

1 CMS Alexander Dierlamm for the CMS TK collaboration INSTITUT FÜR EXPERIMENTELLE KERNPHYSIK Image credit: Andre Holzner KIT The Research University in the Helmholtz Association

2 Baseline Layout 6 barrel layers plus 5+5 endcap disks: 3 inner layers with 2836 PS modules (macro-pixels) to provide accurate z coordinate (TBPS) partially tilted to mitigate stub inefficiency more complex mechanics but better performance with less modules 3 layers of 2S modules (4464) at larger radii (TB2S) Total: modules 2 endcaps (TEDD) with 1248 PS and S modules each TB2S TEDD Barrel TBPS Tilted TBPS

3 p T Module Concept Contribution to L1 trigger requires tracker data at every BX (40 MHz) all hits would exceed bandwidth data reduction at the front end mm pass programmable search window fail B detect high-momentum tracks on module by correlating hits on 2 appropriately spaced sensors stubs stub Concept requires high (asymmetric) bandwidth 2 data paths (via same optical link) fast track reconstruction in the back-end electronics (see Erica and/or Louise (Thu))

4 The p T Modules 2S module two strip sensors (10cm x 10cm) two hybrids with 8 CBC readout chips and data concentration in CIC one service hybrid spacers in AlCF (good CTE match to Si) PS module one strip and one macro-pixel sensor (5cm x 10cm) bump-bonded to MPA two hybrids with 8 SSA readout chips and data concentration in CIC two service hybrids (opto, power) spacers in AlCF base plate in CF for cooling contact 2S module PS module

5 2S sensors PS-s sensor PS-p sensor SENSORS

6 Sensor Types Sensors for 2S modules: ~ 10cm x 10cm silicon strip sensors strips: length 5cm, pitch 90µm AC coupled with poly-silicon bias resistors PS-s sensors ~ 5cm x 10cm silicon strip sensors strips: length 2.5cm, pitch 100µm AC coupled with poly-silicon bias resistors PS-p sensors ~ 5cm x 10cm silicon macro-pixel sensors strips: length 1.5mm, pitch 100µm DC coupled with punch-through biasing PS-s: x mm2 All sensors are of n-in-p type. Fake hits observed on p-in-n sensors after irrad. Working strip isolation determined Thickness between 200µm and 300µm. Macro-pixels on PS-p sensor Status OT Sensors

7 Sensor thickness - I Active thickness between 200µm and 300µm thinner: less leakage current lower depletion voltage thicker: initially more collected charge (reduced difference after irrad.) more contingency at higher bias voltage Thinning of active volume physical thinning sharp doping transition at backplane less material deep-diffusion broader doping transition at backplane passive material helps in heat conduction maybe a cost effective option Seed Signal (e-) 320µm 20k 18k 16k 14k 12k 10k 8k 6k p(mev) p(mev) p(gev) n-in-p 600V, -20 C: 200µm 320µm n n p(gev)+n p(gev) p(mev) p(gev)+n deep-diffusion (200µm dd-fz) n p(mev)+n p(mev) Fluence (10 14 n eq /cm²) 200µm p(mev) physical thinning (200µm FZ) n+ p p+ p+n Status OT Sensors

8 Sensor thickness - II Charge collection vs. deep-diffused active thickness strip sensors with physical thickness of 320µm and active thicknesses of 200, 240 and 300µm have been compared small effect of annealing for thin sensors F= 6-7x10 14 n eq /cm² U= 600V T= -20 C seed (e-) µm dd-fz w@RT 20w@RT Active thickness (µm) Status OT Sensors

9 8x CBC 8x SSA CIC 16x MPA lpgbt & optical VTRx+ (5.12Gbps) DC-DC HYBRIDS AND ASICS

10 Front-end block diagram Readout, correlation logic, data concentration, el.-optical conversion, data transmission and power conversion all integrated in the module!

11 Front End Hybrid Flex hybrid with bump-bonded ASICs bent around spacer/stiffener to route signals from top and bottom sensor to ROCs Current prototypes: dual-cbc2 rigid hybrid for 2 CBC2 used for first small prototypes 8CBC2Flex Full 8 CBC2 readout system 4 layers, 150μm thick No concentrator PS mockup Outline of the folded circuit to enable discussions with test probe suppliers. SSA and CIC footprint is the one of the CBC2, will be adjusted later. SSA and MPA to be submitted in 2017 Power and HV connectors placed Alignment holes for folding and electrical test socket Test probe interface proposal next to SEH-opto wirebond interface. dual-cbc2 hybrid 8CBC2Flex 3D model of the assembled and folded PS mockup hybrid

12 Functional Test System for FE hybrids Objective: Provide electrical interfaces, external test pulses and powering for FE hybrid Allow testing hybrids at -30 C (cool the same spots of FEH which will be cooled in the detector) Reduce thermal capacity of the setup Maintain ease of use and reliability Structure of the setup: Modular design (to easily adapt to different FEHs) 2 Peltier modules as active cooling elements Clamp-on thermal interface between Peltier modules and tested hybrid Interface PCB with spring probes (POGO pins) Structure of the system: Sealed box to keep setup in a dry air environment Two-stage dry air injection system Centralized control and DAQ system on SLC6 PC

13 Front End ASICs CMS Binary Chip (CBC, 130nm) CBC1 (2011) CBC2 (2013ff.) 254 channels ~same front end, pipeline, readout approach as CBC1 Rudimentary correlation and triggering features C4 bump-bond layout, 250 μm pitch, 19 columns x 43 rows Includes triggering features 30 inter-chip signals (15 in, 15 out), top and bottom CBC3 (expected Q4/2016) 254 channels Front end optimized for 5cm strips (up to 8cm), n-polarity Pipeline length 12.8 μs, based on enclosed layout cell Full correlation logic, 320Mbps digital interconnects Macro-pixel ASIC (MPA, 65nm) MPA-light (2015) 3x16 pixels (instead of 16x120) Analog pixel cell identical to final MPA one Rudimentary digital logic Possibility to daisy chain chips and to emulate strip works as expected; rad.-hardness confirmed Full-size MPA to be submitted in 2017 Strip Sensor ASIC (SSA, 65nm) Full size prototype to be submitted 2017 Concentrator (CIC, 65nm) Prototype to be submitted 2017 Raw data (L1) block: Full raw data transmission up to 750kHz (max. acceptable L1A rate) No loss accepted (<0.1%) Trigger block: Full trigger data (stubs) transmission up to 40MHz Small loss (~1%) in the innermost region for good stubs (i.e. coming from particles with p T >2GeV/c and d 0 <5mm) ASICs currently used in prototypes and system tests CBC2 MPA-light

14 Beam Tests with CBC based prototypes 2S mini-modules in BTs (CERN, DESY) Un-irrad. and irrad. to 6x10 14 n eq /cm² p T discrimination confirmed Susceptibility to ext. noise observed in BT environment and being investigated 2S full-size module in BT (CERN) Read-out of 2 x 8CBC2 hybrids Good module performance (noise~1100e-) p T discrimination as expected R=1m, 600V non-irrad. mini-module (DESY) noise ~ 1100eirrad. mini-module (CERN)

15 Service Hybrid VTRx+ Prototype exists Not yet rad-hard Not yet final geometry Feasibility demo in Q2/2017 lpgbt Low power version of GBT Submission Q3/2017 Converter upfeast Second prototype received and being evaluated DCDC2S First prototype expected Q4/2016 Two working shielding options identified Characterization of flex SEH started First system tests with shielded flex hybrid, no significant increase of noise VTRx+ prototype operated on the service hybrid High-voltage circuit on fold-over region on backside

16 Tests with service hybrid prototype Prototype based on flex hybrid and early prototypes of converter ASICs Efficiency can be measured here: two non-final DCDC converters final efficiency expected ~64% Test el.-mag. emission of various shielding options Noise tests prototype hybrid does not influence noise of close-by mini-module significantly Flex SEH prototype 48% prototype SEH dual CBC2 mini-module

17 MAPSA (MACRO-PIXEL SUB ASSEMBLY)

18 Macro-Pixel Subassembly 16x MPA bump-bonded on 5cm x 10cm macro-pixel sensor channels MaPSA-light prototype Assembly of 3 x 2 MPA-light chips for a total of 288 pixels Bump-bondable to detector Wire-bondable to hybrid 5.4mm x 12.7mm MaPSA-Light is test vehicle in timeframe Micro-module to mimic PS module in Q4/16 MaPSA-light prototype MaPSA-light MaPSA-light Micro-module

19 Beam Tests with MaPSA-light MaPSA light in BT (FermiLab) most assemblies well connected good performance in BT eff. vs. clock phase measured FNAL beam tests of the micro-module are scheduled for first week of December full-size mod

20 ASSEMBLED MODULES

21 Thermal Tests of Modules Thermal performance investigated by FEM simulations CO 2 around -30 C should keep sensors at -20 C and no thermal runaway Trade-off between mass and thermal performance Thermal prototypes being studied PS thermal dummy 2S ANSYS simulation PS ANSYS simulation 5 cooling points cooling via CF plate Thermal runaway: 1.8mm: C 4.0mm: C Thermal runaway: 1.6mm: -12 C 2.6mm: -20 C 4.0mm: -22 C

22 Module Assembly Requirement: tilt < 40µm between sensors Use diced sensor edge for alignment on precision jig Two modules built and measured: 14 / 1 μrad (27 / 13 μrad RMS) goal: < 400µrad

23 Functional Tests during Module Production In the process of module construction, two functional tests to check connectivity and functionality are foreseen: after wire-bonding and after encapsulation For the functional tests, each assembly line will be equipped with: FC7 based DAQ a cold box for modules on carrier

24 MECHANICS

25 Status Overall tracker concept profits a lot from the present CMS Tracker. New features to be covered: Forward extension: Good progress with OT Pixels boundary and Beam-pipe design efforts (see Julia s talk). New (improved) beam-pipe supports need to be designed. CO 2 cooling systems: Scaling up from the Pixel phase 1 upgrade to be done. Design of YB0 services is a complex task, requires central CMS coordination and resources. Good progress with the sub-detector design, no show-stoppers seen Assembly designs to be completed for TEDD and TBPS. More prototyping needed to prove manufacturing techniques and thermal performance. Cooling distribution needs to be designed to detail level and proven with tests (this is a big job)

26 TBPS section Tilted and Flat sections are pre-assembled separately. Longitudinal profiles join the sections of one layer and provide for services routing paths. Layer 1 includes also the central section of the Pixel support tube. Small, few mm clearance to the closest modules in the flat section. Ring Plank Modules are mounted on plates on the individual rings

27 TEDD Section + - Each end cap consists of five double-disks Each double-disk consists of two double-dees (+ and -) Modules are mounted on front and back sides of Dees overlap in phi established within Dee overlap in radius established within doubledisk TEDD has both 2S and PS modules, need suitable supports and cooling for both module types. Cooling pipes embedded in the Dee sandwich structure. Geometrically complex

28 Cooling System and Module Contacts Phase 2 cooling system: Scale-up of what was developed for Pixel phase 1 Bigger cooling plants planned (45-60 kw) Nominal total load: ~120 kw TB2S = 25 kw TBPS = 25 kw 2 x TEDD = 2 x 20 kw Pixels: kw CO 2 temperature at detector: -30 C Maintain < 0 C when detector off Module cooling concepts Stainless steel cooling pipes (D=2.2mm, d=100µm) 2S modules via Al inserts PS modules via thermal transfer plate Al insert for 2S modules

29 Dee Prototype Thermal Tests Prototype connected to conventional cooling system Check thermal interface between C-foam and facing Looks promising as a diagnostics tool, but work in progress

30 Summary and outlook CMS Tracker just went through comprehensive review with good feedback and no significant concerns in the Outer Tracker Designs of both 2S and PS modules are well understood Close to final read-out chips will appear in 2017 and intense system test program will start with module prototypes Good progress in the design of the sub-detector support structures no show-stoppers seen so far Prototyping of support structures has started to prove manufacturing techniques and thermal performance Technical design report to be submitted in 2017 Overall, the developments are well advanced and well supported, on track with respect to the installation date the construction will be a big effort, gathering and organizing the necessary teams is a challenge

31 SPARES

32 Pixel PS 2S Radiation environment Sensors for 2S modules to be tested up to 6x10 14 n eq /cm² Sensors for PS modules to be tested up to 2x10 15 n eq /cm² max. fluence max. dose 2S 4.71x kGy PS 1.12x kGy Status OT Sensors

33 Requirements for the CMS Tracker Requirement Reason radiation tolerance & cold(er) operation withstand fluence equivalent to 3000 fb -1 higher granularity track trigger capabilities / identify high pt 40 MHz deep front-end buffers and high readout bandwidth keep occupancy O(1%) to deal with PU and for robust track separation contribute to the CMS L1 Trigger to be compatible with longer L1A latency of 12.4 us and higher L1A rate (750 khz) reduction of material budget improve tracking performance / momentum resolution extend acceptance to η~4 particle flow in deep forward region

34 Fake hits in irrad. p-in-n type sensors After irradiation > 5x10 14 n eq /cm² high fields at p+ strips lead to non-gaussian noise and fake hits in 200µm p-in-n sensors n-in-p sensors do not show this effect Normal noise dist. Noise dist. causing fake hits Status OT Sensors

35 Strip isolation One needs a minimum p-stop concentration to provide isolation, but too high concentration can create high electric fields after radiation damage, which can generate fake hits (RGH) p-stop peak concentration ~1x10 16 cm -3 PhD, Martin Printz, Status OT Sensors

36 MaPSA-light

37 PS module flavors and power estimates

38

39 CIC1 block diagram

40 CBC3 block diagram

41 OT-Pixel Transition region Pixel support tube