A new strips tracker for the upgraded ATLAS ITk detector

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1 A new strips tracker for the upgraded ATLAS ITk detector, on behalf of the ATLAS Collaboration : 11th International Conference on Position Sensitive Detectors 3-7 The Open University, Milton Keynes, UK.

2 From LHC to High-Lumi LHC Schedule LHC Run LHC Run 3 Technical stop Installation HL-LHC 2037 HL-LHC Run TeV 13 TeV Nominal luminosity 2 nominal luminosity 5-7 nominal luminosity cm-2.s-1 Collected data: Right now ~16 fb fb-1 ~3000 fb fb-1 Peak lumi = cm-2.s-1 order of (trillions) proton-proton collisions 2016 Need of a decisive increase in luminosity to significantly extend statistical sensitivity to new physics to maximize performance for precision measurements fully exploit LHC s singular potential The High-Luminosity LHC program 2

by all-silicon tracker ITk ATLAS Upgrade (Phase II) Sustain and

3 The Inner Tracker of the ATLAS detector Now End-cap For HL-LHC Goals: Barrel End-cap Current inner tracker to be fully replaced by all-silicon tracker ITk ATLAS Upgrade (Phase II) Sustain and improve the excellent performance of ATLAS Run 2 in denser environment 3

Overview of new strip tracker of ATLAS Upgrade II Overall layout Y [mm]

160 m2 Nb channels 580 millions 50 millions Pixel barrel Pixel end-cap beam

electronics > modules > support structures For (much) more details: Technical

4 Overview of new strip tracker of ATLAS Upgrade II Overall layout Y [mm] Quarter segment Strips end-cap Strips barrel Pixel Strips Silicon area 13 m2 160 m2 Nb channels 580 millions 50 millions Pixel barrel Pixel end-cap beam pipe This presentation [m] Focus on the strips region of the ITk sensors > electronics > modules > support structures For (much) more details: Technical Design Report, April

Silicon sensors Silicon sensors n+-in-p float-zone (FZ) Now = p-in-n Inner strip isolation p-spray/stop collects electrons: more

Bias ring Technology Good signal even under-depleted (depletion on segmented side) more available foundries worldwide sensor

trapezoidal shape for r-φ coverage ~97 mm Radial strips pointing to beam axis wedge-shaped sensors with curved edges ~97 mm Long:

5 Silicon sensors Silicon sensors n+-in-p float-zone (FZ) Now = p-in-n Inner strip isolation p-spray/stop collects electrons: more & faster signal, less trapping no radiation-induced type inversion p bulk single-sided process cheap & easy μm Guard ring Bias ring Technology Good signal even under-depleted (depletion on segmented side) more available foundries worldwide sensor edges at bias potential (~700 V) design based on 6-inch wafer technology Sensor shapes & pitch Barrel rectangular End-caps trapezoidal shape for r-φ coverage ~97 mm Radial strips pointing to beam axis wedge-shaped sensors with curved edges ~97 mm Long: 48.2 mm 75.5 μm Strip pitch μm Short: 24.1 mm Strip length mm chosen to balance higher occupancy regions with shortest strips 5

readout electronics Connection to strips by wire-bonds

6 Strip Module = Silicon sensor + hybrid + power board New: low mass PCB s directly glued on sensor Hosting readout electronics Connection to strips by wire-bonds Total number of modules = designed for mass production 6

Signals & Electronics Front-end read-out Charged particles through sensor signal charge Conversion in hit signal in ABCStar binary ASICs using 130nm tech 256 channels Hybrid

5 V radiation-hard upfeast chip controls parallel powering Baseline: L1 trigger rate = 1 MHz Autonomous Monitor and Control Chip local monitoring of current/voltage/temperature

7 Signals & Electronics Front-end read-out Charged particles through sensor signal charge Conversion in hit signal in ABCStar binary ASICs using 130nm tech 256 channels Hybrid Controller Chip (via power bus) HCCStar Packed signals sent to End-of-Substructure via bus tapes Power board Clock & Trigger rates Point of load DC-DC conversion 10.5 V 1.5 V radiation-hard upfeast chip controls parallel powering Baseline: L1 trigger rate = 1 MHz Autonomous Monitor and Control Chip local monitoring of current/voltage/temperature controls HCC, ABC, HV switch HCC130 ASICs TTC data 160 Mbit/s EoS Module data 640 Mbit/s Multiplexer: controllable switch, allows connection/isolation of individual sensor to single HV line 7

Module support (1/2) System unit: a sandwich Modules directly glued on both sides of a light carbon-fiber support structure Cooling system embedded (bi-phase CO2 cooling at -35 C) Cross section

8 Module support (1/2) System unit: a sandwich Modules directly glued on both sides of a light carbon-fiber support structure Cooling system embedded (bi-phase CO2 cooling at -35 C) Cross section Minimizing material short thermal paths ~ 3 mm reduced radiation length ~ 2% [x/x0] Simplicity for large scale reproducibility Core and electronic components individually testable before assembly 8

9 Module support (2/2) more details in Ankush s talk on Friday Barrel staves End-cap petals Stave module Modules mounted on core structures EoS 4 1. m Cooling loop 60 cm 30 cm EoS ~12 cm 9

10 Ongoing R&D 10

Irradiation tests: TID induced current increase STI Total Ionizing Dose (TID) induced current increase Irradiation with X-rays increase of digital current in ABC130 ASIC radiation n+ depends on p

11 Irradiation tests: TID induced current increase STI Total Ionizing Dose (TID) induced current increase Irradiation with X-rays increase of digital current in ABC130 ASIC radiation n+ depends on p Radiation creates trapped charges in oxide higher doses F. Faccio and G. Cervelli, Radiation-induced edge effects in deep submicron CMOS transistors, IEEE Transactions on Nuclear Science 52 (2005) Current increase up to 2.5 times Intensive studies ongoing to: characterize model dissip. power irradiation tests Pdissip = f(position, fluence) feeds FEA simulations design and layout of the strip detector is sturdy enough to incorporate this feature 11

Irradiation tests: testbeam results (1/2) Comparison of performance

sensors irradiated beam tracks matched to strip hits using

telescope MIMOSA sensors Threshold scans Irradiation of Long Strip

Energy Loss: 8 1014 neq. cm-2 Total Ionizing Dose: 37.

12 Irradiation tests: testbeam results (1/2) Comparison of performance before and after irradiation Long Strip module 4 (LS4) miniature sensors irradiated beam tracks matched to strip hits using EUDET-type telescopes (CERN & DESY) DESY Telescope DESY telescope telescope MIMOSA sensors Threshold scans Irradiation of Long Strip module 3 at CERN Proton Synchrotron 24 GeV protons Non-Ionizing Energy Loss: neq. cm-2 Total Ionizing Dose: 37.2 MRad Max level of radiation expected in the strip system charge collection reduced after irradiation 12

13 Irradiation tests: testbeam results (2/2) Expected end-of-lifetime performance Specs: hit efficiency > 99% Hit efficiency (obtained using track reconstruction of telescope data) Specs: NC < 10-3 (signal-to-noise 10:1) hit efficiency ABC130 noise occ. New front-end noise occ. Very small working window with ABC130 Range of thresholds meeting the 2 specs much wider with new front-end stage for ABCStar chip 13

14 Prototype characterization Stave barrel End-cap petal Threshold scans R0 module Complete modules currently tested pre/post-irradiation Thermomechanical prototype petal Ongoing tests: metrology readout developments infrared measurements mechanical stress comparison to FEA simulations Working on detailed Quality Control & Quality Assurance procedures 14

with high levels of radiations coping with 5 times more pile-up: from 40 to 200 Milestones and achievements Intensive R&D activities performed by numerous institutes within

15 On the road to Design of the new inner tracker for the upgraded ATLAS detector Proposed tracker designed to meet the requirements of the High-Luminosity LHC program dense environment with high levels of radiations coping with 5 times more pile-up: from 40 to 200 Milestones and achievements Intensive R&D activities performed by numerous institutes within the ITk collaboration strong prototyping effort to optimize stave and petal structures irradiation and testbeam data taking June 2017 CERN Research Board approved the Phase-II ITk Strip TDR Ongoing Research & Schedule Ongoing tests & simulations to further help reaching desired sensitivity of HL-LHC analyses End of 2017 pixel TDR 15

16 Backups 16

17 High-Luminosity LHC requirements Coverage Speed Radiation hardness Granularity Expanding eta coverage Reduce lower inactive material Fast electronics High bandwidth sensors & electronics to withstand 10 radiation levels of current inner strip tracker dense environment: ~200 collisions/bunch crossing occupancy < 1% 17

18 Edge & multiple strip behaviour Hit occupancy Flat efficiency, Consistent with strip pitch 74.5 μm Average cluster size along strips Charge charing highest for electrons passing in between 2 strips Drop due to charge sharing between strips Strip 1 Strip 2 Strip 3 Strip 4 18

19 Charge Collection Efficiency after Irradiation Estimated collected charge vs fluence Miniature devices irradiated to strip barrel radiation level with neutrons, pions, protons saf ety Maximal expected fluence within ITk strip 1.5 Bias voltage: 500 V fac tor Bias voltage: 700 V Expected collected 500 V V ke 19

20 ITk strips collaboration Around 200 people involved in ITk strips 20

ATLAS strip detector upgrade for the HL-LHC

ATLAS strip detector upgrade for the HL-LHC ATL-INDET-PROC-2015-010 26 August 2015, On behalf of the ATLAS collaboration Santa Cruz Institute for Particle Physics, University of California, Santa Cruz E-mail: zhijun.liang@cern.ch Beginning in 2024,