Tracking system technology challenges and possible evolution Lucie Linssen, CERN Using slides from: Tony Affolder, Saverio D’Auria, Dominik Dannheim, Erik van der Kraaij, Sandro Marchioro, Luciano Musa, Ivan Peric, Petra Riedler, Walter Snoeys, etc. FCC workshop, March 25 th

outline Lucie Linssen, March 25th Tracking requirements for FCC-hh Parameters defining in tracking performance Comparison of LHC / HL-LHC / CLIC / FCC-hh requirements Overview of solid-state tracker technologies Technology examples Summary DISCLAIMER This presentation is subjective and incomplete Not paying justice to the broad field of ongoing tracker R&D MAIN TAKE-HOME MESSAGE Be optimistic about what can be achieved in 2 decades of R&D ! DISCLAIMER This presentation is subjective and incomplete Not paying justice to the broad field of ongoing tracker R&D MAIN TAKE-HOME MESSAGE Be optimistic about what can be achieved in 2 decades of R&D !

FCC-hh tracking environment Lucie Linssen, March 25th Some basic assumptions: pp centre-of-mass energy: 100 TeV Luminosity:5×10 34 in the 1 st phase 30×10 34 in a 2 nd phase Pile-up:[170, then 1020] events at 25 ns spacing [34, then 204] events at 5 ns spacing Average/maximum occupancy:~50% higher than at 14 TeV Integrated luminosity3 ab -1 for the 1 st phase 30 ab -1 for a 2 nd phase Expected radiation level3x10 16 cm -2 1MeVneq fluence (1 st phase) 10MGy Dose (1 st phase) η coverage up to η= 4 (~2 degrees) or η= 6 (~0.3 degrees)

FCC-hh tracking performance requirements Lucie Linssen, March 25th Time resolution a few ns hit timing accuracy assumed Momentum resolution Assume σ(p T )/p T of ~10% needed for isolated objects of very high energy What resolution will be needed for lower p T, e.g. particle in jets ??? Impact parameter resolution Aim for significantly better than current LHC performances ??? σ(rϕ) << 70 μm at 1 GeV σ(rϕ) << 10 μm at 1 TeV

tracking + impact parameter resolution Lucie Linssen, March 25th Momentum resolution => to get p T resolution similar to LHC => try to gain a factor 7 in σ/(BR 2 ) Impact parameter resolution dominated by single-point resolution multiple-scattering term => low material! => impact of #material on accuracy is most important in the vertex region

momentum resolution at high p T Lucie Linssen, March 25th Momentum resolution (assuming CMS-like solenoid geometry)  to get p T resolution similar to LHC => try to gain a factor 7 in σ/(BR 2 ) Increase B-field ?: =>=> very challenging/risky/expensive to go above 4T (CMS) Increase single-point resolution ?: Current CMS/ATLAS =>=> ~20-25 μm Room for improvement =>=> factor ≥4 (10??) in central region =>=> Resulting increase in tracker radius would be: < √7/4 ≈ <30% What is the p T resolution needed at large η ? Worth studying to stretch coil and tracker in z to increase coverage Penalty on #material (e.g. longer/stronger supports and longer cables)

resolution in vertex detector ? Lucie Linssen, March 25th CLIC aims for: ~25 times smaller pixel size than current CMS/ATLAS ~10 times less material/layer than current CMS/ATLAS Given the long time-scale, one can assume a CLIC-like accuracy goal for FCC-hh (??) Impact parameter resolution dominated by single-point resolution multiple-scattering term => low material! CLIC goal a = 5 μm b = 15 μm goal

comparison of requirements Lucie Linssen, March 25th CLIC ALICE upgrade HL-LHC FCC-hh Radiation hardness Position resolution Timing accuracy Low mass HL-LHC ALICE upgrade FCC-hh CLIC ALICE upgrade HL-LHC CLIC FCC-hh HL-LHC ALICE upgrade FCC-hh CLIC weaker very strong The 4 listed projects have many individual requirements in common, though their combination is different

Si technology types Lucie Linssen, March 25th HybridMonolithic3D-integrated ExamplesATLAS, CMS, LHCb- Velo, Timepix3/CLICpix HV-CMOS, MAPSSOI, wafer-wafer bonded devices TechnologyIndustry standard for readout; special high-Ω sensors R/O and sensors integrated, close to industry standards Currently still customised niche industry processes InterconnectBump-bonding required Connectivity facilitated Connectivity is part of the process GranularityMax ~25 μmDown to few-micron pixel sizes TimingFastCoarse, but currently improving with thin high-Ω epi-layers Fast Radiation hardness “Feasible”To be proven??

Lucie Linssen, March 25th Hybrid detector technology

ATLAS/CMS tracker upgrades Lucie Linssen, March 25th z [m] Significant progress in: Integration, production, radiation hardness Powering and services Less material (gain >2) Smaller cell sizes Due to lack of time, and given well-informed audience, CMS/ATLAS work not further addressed in this talk

CLIC vertex/tracker requirements Lucie Linssen, March 25th m (calorimeter) pixel detector tracker CLIC vertex detector requirements 3 μm single point accuracy 25*25 μm 2 pixels Pulse height measurement Time measurement to 10 ns Ultra-light => 0.2%X 0 per layer Power pulsing, air cooling Aim: 50 mW/cm 2 Radiation level ~10 4 lower than LHC ongoing R&D covering several disciplines CLIC tracker requirements Radius 1.5 m, half-length 2.3 m 7 μm single point accuracy Large pixels/short strips Time measurement to 10 ns Ultra-light => 1%X 0 per layer Radiation level ~10 4 lower than LHC R&D just starting FCC-hh accuracy requirements may be quite similar With in addition: Radiation hardness Buffering/Triggering ? Large data rates

CLIC vertex detector => hybrid baseline Lucie Linssen, March 25th CLICpix demonstrator ASIC 64×64 pixels, fully functional 65 nm technology 25×25 μm 2 pixels 4-bit ToA and ToT info Data compression Pulsed power: 50 mW/cm 2 Hybrid baseline option: Thin ~50 μm silicon sensors Thinned high-density readout ASIC, ~50 μm R&D within Medipix/Timepix effort Low-mass interconnect (TSV) Very thin sensors Tested with Timepix ASICs (55 μm pitch) 1.6 mm 64×64 pixels RD53 collab. !

effect of sensor thickness on charge sharing Lucie Linssen, March 25th Effect of sensor thickness on charge sharing: Beam impact positions at the single pixel level for different cluster sizes and for different sensor thicknesses. Data taken with 55 μm readout pixels (Timepix) Sensor thickness: 50 μm 100 μm 150 μm 200 μm 500 μm Cluster size 2 Cluster size 3 Cluster size 4 Cluster size 1 Effect of sensor thickness on charge sharing: Beam impact positions at the single pixel level for different cluster sizes and for different sensor thicknesses. Data taken with 55 μm readout pixels (Timepix) Sensor thickness: 50 μm 100 μm 150 μm 200 μm 500 μm Cluster size 2 Cluster size 3 Cluster size 4 Cluster size 1 Effect of sensor thickness on charge sharing: Beam impact positions at the single pixel level for different cluster sizes and for different sensor thicknesses. Data taken with 55 μm readout pixels (Timepix) Sensor thickness: 50 μm 100 μm 150 μm 200 μm 500 μm Cluster size 2 Cluster size 3 Cluster size 4 Cluster size 1 Effect of sensor thickness on charge sharing: Beam impact positions at the single pixel level for different cluster sizes and for different sensor thicknesses. Data taken with 55 μm readout pixels (Timepix) Sensor thickness: 50 μm 100 μm 150 μm 200 μm 500 μm Cluster size 2 Cluster size 3 Cluster size 4 Cluster size 1 Sensor thickness: 50 μm 100 μm 150 μm 200 μm 500 μm Cluster size 2 Cluster size 3 Cluster size 4 Cluster size 1 55 μm pixel size

position resolution and charge sharing Lucie Linssen, March 25th Charge-sharing is important to achieve Position accuracy Holds both for analog and digital readout Conflict of low mass  charge sharing ( Charge-sharing can be enhanced with signal collection through diffusion, but this is in conflict with timing requirements and radiation requirements. ) 50 μm thin sensor 55 μm pixel pitch 2-hit clusters 1-hit clusters Beam test with accurate reference telescope Ultimately, a strong limit to the hybrid solution is the bump-bonding pitch (and cost!). => Currently prevents pushing to ever smaller pixel sizes

Lucie Linssen, March 25th Monolithic detectors

integrated MAPS technology Lucie Linssen, March 25th MAPS: Integrated electronics functionalities Allows for small pixel sizes No need for expensive bump-bonding HV-CMOS: Possible in advanced 180 nm (350 nm) High Voltage process V bias ~100 V, μm depletion layer Fast signal collection from depleted layer Radiation hardness improves when fully depleted, needs further R&D

MAPS, early application (1994) Lucie Linssen, March 25th μ m 125 μ m 2 μm technology 300 μm thick, high resistivity P-type σ = 2 μm Excellent S/N of 150 for MIP Charge sharing with analog readout C. Kenney et al. NIM A 342 (1994) 59-77

ALICE inner tracker upgrade Lucie Linssen, March 25th cm 1.5 cm Soldering pads  ~ pixels of 28 x 28 μm nm Tower Jazz process MAPS-type 3 inner barrel layer (IB) 4 outer barrel layers (OB) Radial coverage mm 12.5 Giga-pixel tracker 10 m cm 2 Large single cell of 4.5 cm 2 Few contacts, laser bonded to flex For installation in ALICE in LS2 (2019)

ALICE inner tracker upgrade Lucie Linssen, March 25th All-pixel design, pixel pitch 28 μm Single-point resolution 5 μm Sensors not fully depleted, not a fast signal ~2 μs hit time resolution Radiation level: 700 krad / MeV neq (includes safety factor 10) Low-mass design: 0.3%X 0 in inner layers 0.8%X 0 in outer layers Power density <100 mW/cm 2

hybrid of HV-CMOS with readout ASIC Lucie Linssen, March 25th Hybrid option: Capacitive Coupled Pixel Detector (CCPD) HV-CMOS chip as integrated sensor+ amplifier Capacitive coupling to complex readout ASIC through layer of glue => no bump bonding

hybrid vertex detector with HV-CMOS Lucie Linssen, March 25th Hybrid option with HV-CMOS: Capacitive Coupled Pixel Detector (CCPD) HV-CMOS chip as integrated sensor + amplifier Capacitive coupling to CLICpix (or FEI4) ASIC through layer of glue => no bump bonding CCPDV3 R&D pursued by e.g. ATLAS and CLIC successful initial beam tests in 2014 Further beam tests in 2015 HV-CMOS + CLICpix, AC coupled

Lucie Linssen, March 25th D integrated detectors

3D detectors, wafer-to-wafer bonding Lucie Linssen, March 25th SOI 3D-integrated, 3 tiers 3D technologies, wafer-to-wafer bonded ASIC + sensor Main advantages: Combining optimal sensor material (high-Ω) with high performance ASIC Avoid bump-bonding Profit from industrial CMOS trends towards very small feature sizes Drawbacks: Currently either still niche application (e.g. SOI) or fast-changing industrial R&D (e.g. R&D for cameras with very small pixels) Generally too high cost for particle physics R&D budgets We have to stay open to grab future opportunities in such domains

engineering…. Lucie Linssen, March 25th Talk is too short to cover important (engineering) issues: Interconnect technologies Powering Services Cooling Light-weight supports New materials Detector stability and alignment These engineering items are crucial parts of the R&D Requiring fully integrated apparoach

conclusions Lucie Linssen, March 25th Mostly copied/adapted from Saverio d’Aurio, Feb 2015 Detectors for FCC-hh inner tracking are considered feasible ~ns time resolution, ~micron-level space resolution and radiation tolerance to ~30x10 16 appear as natural evolution of present technologies. Minimal FCC-hh target specifications are almost already achieved in dedicated detectors. However, no single technology reaches all design specs at the same time. The main issue: coverage at small radius with radiation hardness, fine granularity. Several sensor technologies are promising => consider them all Microstrips will most likely be replaced by pixels everywhere. Big technology step: integrated electronics => to be pursued closely Important to develop all integrated design details among physicists, microelectronics experts, mechanical engineers and material scientists Room for several future projects to join forces

Lucie Linssen, March 25th SPARE SLIDES

comparison main tracker LHC vs. CLIC Lucie Linssen, March 25th Momentum resolution for high p T (η=2) CLIC tracker requirements 7 μm single point accuracy time-stamping 10 ns ~5-6 tracking layers Radius ~1.5 m, half-length ~2.3 m High occupancies in certain regions: Requires large pixels and/or short-strips Very light => ~1%X 0 per layer

CLIC vertex detector optimisation Lucie Linssen, March 25th Spiral disks Single layers Spiral disks double layers Using flavour tagging as a gauge 1.Test single vs. double layers 2.More realistic material (0.2% X0/layer) 3.Vary inner radius (for 4 T or 5 T B-field) double layer better single layer better larger inner radius better Inner radius 27 mm / 31 mm 0.1% X 0 /layer / 0.2%X 0 /layerSingle layers / double layers more material better Work in progress !

CLIC pixel detector and flavour tagging Lucie Linssen, March 25th

CLIC main tracker and B-field choice Lucie Linssen, March 25th x BR 2 Large tracker size has advantage R =1.5 m Half-length = 2.3 m (stretched wrt CDR) B-field gives +10% improvement for +0.5 T Compromise: 4 T (inner bore radius ~3.2 m) Jet performance was checked for those values θ=90 o θ=20 o Work in progress !

SOI Lucie Linssen, March 25th