Mimosa 9: resolution vs pitch 3.5 Resolution (microns) 3 CLIC Workshop - CERN, Octobre 16-18, 2007 2.5 ILC-VD - 2 1.5 1 15 20 25 30 35 40 45 Pitch (microns) High Resolution Pixel Technologies Developed for an ILC Micro-Vertex Detector Marc Winter (IPHC-Strasbourg) contributions: V.Re (CMOS sensors / INFN-Pavia), L.Andricek (DEPFET / MPI-Munich), M.Demarteau (3D sensors / FNAL-Chicago) ⊲ More information on ILC Web site: http://www.linearcollider.org/cms/ OUTLINE • Requirements for a Vertex Detector at ILC ≎ Constraints from physics goals ≎ Constraints and Benefits from running conditions ≎ Example of vertex detector geometry • Vertex detector technologies easiest to transpose to CLIC running ≎ CMOS sensors (1st & 2nd generation) ≎ DEPFETS ≎ 3D integrated sensors • Conclusion – Perspectives CLIC–WS07, –1–
Mimosa 9: resolution vs pitch Resolution (microns) 3.5 3 2.5 ILC-VD - 2 1.5 1 15 20 25 30 35 40 45 Pitch (microns) Main Requirements for the ILC Vertex Detector : • Physics goals • Running conditions CLIC–WS07, –2–
Mimosa 9: resolution vs pitch Resolution (microns) 3.5 Constraints from the Physics Goals 3 2.5 ILC-VD - 2 1.5 1 15 20 25 30 35 40 45 Pitch (microns) � Overall objective: identify ∼ all flavours involved in most final states Ex: e + e − ZH ⇛ measure Br ( H cc , τ + τ − , bb , gg , ... ) � In practice: ⊲ tag c and τ jets with unprecedented efficiency & purity ( b tagging much less challenging) ⊲ reconstruct very efficiently Vx1 Vx2 Vx3 .... ⊲ reconstruct vertex flavour and electrical charge ... ⊲ cope with high jet multiplicity final states containing numerous b , c , τ jets ⊲ minimise secondary interactions (missleading particle flow reconstruction) ⊲ etc. � σ IP = a ⊕ b / p · sin 3 / 2 θ with a < 5 µm and b < 10 µm ⊲ limits on a and b are still ”very educated guesses” ⊲ SLD: a = 8 µm and b = 33 µm • σ sp � 3 µ m • R in ∼ 1–2 cm • R out ∼ 4 · R in • VD layer ∼ 0.1–0.2 % X 0 • beam pipe ∼ 0.1 % X 0 � Constraint on σ IP satisfies simultaneoulsy requirement on 2-hit separation in inner most layer ( ∼ 30 – 40 µm ) CLIC–WS07, –3–
Mimosa 9: resolution vs pitch Resolution (microns) 3.5 Constraints from the Running Conditions 3 2.5 ILC-VD - 2 1.5 1 15 20 25 30 35 40 45 Pitch (microns) � Overall objective: come as close as possible to IP minimise a and b ( ∝ R in ) ⇛ beam background induced by high luminosity : Beamstrahlung e ± ⇛ inner layer constraints prevent a & b to be well below their upper bounds → Inner most layer: BG generates O(10 7 ) hits/s while Physics generates O(10 2 ) hits/s ֒ � In practice: ⊲ experimental magnetic field should be as high as possible ( ∼ 3–5 T) sweep away most e ± BS BS rate still � 5 hits/cm 2 /BX at R=15 mm ( √ s = 500 GeV, 4 T) O(10 3 ) pixels /cm 2 /10 µs ⊲ e ± ⊲ foster high read-out speed in inner layers against occupancy � few tens of µ s • 6 · 10 11 e ± 10 MeV ≈ 2 · 10 10 n eq /cm 2 /yr ⊲ rad. level not negligible at T room (mat. budget ?): • ∼ 50 kRad/yr • ∼ 2 · 10 11 n eq /cm 2 /3 yr ⊲ prediction accuracy ⇛ prepare for 3 ? 5 ? times more BG • ∼ 500 kRad/3 yr ⋄ neutron dose integrated over 3 years much smaller : � 3 · 10 10 n eq /cm 2 (safety factor of 10) � Power dissipation : avoid increasing mat. budget & complexity with heavy cooling ⇛ air flow ⋄ exploit beam time structure: ∼ 1 ms train ( ∼ 3000 buckets) every ∼ 200 ms ⇛ duty cycle ∼ 1/200 ⇛ switching off the sensors between trains may allow power reduction by factor of ∼ 100 � EMI : fear that beam delivery elements may be source of very short λ EM field ⋄ some sensor architectures developed (variants of CCD & CMOS sensors) foresee r.o. delayed after end of train → not transposable to CLIC running conditions ⇛ not reviewed in this report ֒ CLIC–WS07, –4–
Mimosa 9: resolution vs pitch Resolution (microns) 3.5 Example of Basic Vertex Detector Design features 3 2.5 ILC-VD - 2 1.5 1 15 20 25 30 35 40 45 Pitch (microns) � ILD geometry: ≥ 5 cylind. layers (R = 15–60 mm), � cosθ �≤ 0.90 – 0.96 ⊲ SiD: shorter barrel & fw/bw disks � L0 and L1 : optimised against occupancy � L2, L3 and L4 : optimised against power dissipation � Pixel pitch varied from ∼ 20 µm (L0–L1) to � 30 µm (L2–L4) minimise P diss N lad N pix P inst diss P mean Layer Radius Pitch t r.o. diss (10 6 ) ( µm ) ( µs ) (mm) (W) (W) < 100 < 5 20 25 L0 20 25 15 ≤ 25 ≤ 26 ≤ 65 < 130 < 7 50 25 L1 ∼ 100 < 90 < 5 L2 37 33 24 50 ∼ 100 < 120 < 6 L3 48 33 32 80 ∼ 100 < 125 < 8 33 40 150 L4 60 330 < 600 3–30 Total 142 � Ultra thin layers: � 0.2 % X 0 /layer ( extrapolated from STAR-HFT; � 40 µm thin sensors ) � Very low P mean diss : << 100 W (exact value depends on duty cycle) � Fake hit rate � 10 − 5 whole detector ∼ = close to 1 GB/s (mainly from e ± BS ) CLIC–WS07, –5–
Mimosa 9: resolution vs pitch Resolution (microns) 3.5 3 2.5 ILC-VD - 2 1.5 1 15 20 25 30 35 40 45 Pitch (microns) PIXEL TECHNOLOGIES DEVELOPED for the ILC Vertex Detector : CLIC–WS07, –6–
Mimosa 9: resolution vs pitch Resolution (microns) 3.5 CMOS Sensors: Main Features 3 2.5 ILC-VD - 2 1.5 1 15 20 25 30 35 40 45 Pitch (microns) � p-type low-resistivity Si hosting n-type ”charge collectors” • signal created in epitaxial layer (low doping): Q ∼ 80 e-h / µm �→ signal � 1000 e − • charge sensing through n-well/p-epi junction • excess carriers propagate (thermally) to diode with help of reflection on boundaries with p-well and substrate (high doping) � Specific advantages of CMOS sensors: ⋄ Signal processing µ circuits integrated on sensor substrate (system-on-chip) �→ compact, flexible ⋄ Sensitive volume ( ∼ epitaxial layer) is ∼ 10–15 µm thick − → thinning to ∼ 30–40 µm permitted ⋄ Standard, massive production, fabrication technology − → cheap, fast turn-over ⋄ Room temperature operation ⋄ Attractive balance between granularity, mat. budget, rad. tolerance, r.o. speed and power dissipation ⋉ Very thin sensitive volume impact on signal magnitude (mV !) ⋊ ⋉ Sensitive volume almost undepleted impact on radiation tolerance & speed ⋊ ⋉ Commercial fabrication (parameters) impact on sensing performances & radiation tolerance ⋊ CLIC–WS07, –7–
Mimosa 9: resolution vs pitch Resolution (microns) 3.5 CMOS Sensors with Analog Output 3 2.5 ILC-VD - 2 1.5 1 15 20 25 30 35 40 45 Pitch (microns) � Numerous MIMOSA chips tested on H.E. beams ( SPS, DESY ) �→ well established perfo. ( analog output ): • Best performing technology: AMS 0.35 µm OPTO ( ∼ 11–15 µm epitaxy) • N ∼ 10 e − �→ S/N � 20–30 (MPV) ⇛ ǫ det ∼ 99.5–99.9 % for fake rate � 10 − 5 • T oper. � 40 ◦ C • Spatial resolution exploits charge sharing between pixels: σ sp ∼ 1 – 1.5 – 2 – 3 µm for 10 – 20 – 30 – 40 µm pitch O(10 13 ) e ± (10 MeV) ; � O(10 13 ) n eq /cm 2 • Radiation tolerance: � 1 MRad (10 keV X-Ray) ; • Technology without epitaxy also performing well : very high S/N but large clusters (hit separation ց ) • Macroscopic sensors : MIMOSA-5 ( ∼ 3.5 cm 2 ; 1 Mpix); MIMOSA-20 (1x2 cm 2 ; 200 kpix); MIMOSA-17 (.8x.8 cm 2 ; 65 kpix) • Several 0.3–3 cm 2 sensors thinned successfuly to � 50 µm • Sensors adapted to applications with � 10 3 frames/s: B.T. of EUDET (FP6), TAPI (Strasbourg), of LBNL; STAR telescope hsn1 hsn1 Mimosa 9: resolution vs pitch Signal/noise in 1 pixels Efficency vs Temperature Small Diode Mimosa 9. Efficiency VS Fake Entries Entries 6067 6067 100.2 3.5 Events Efficency % Resolution (microns) 180 Detection efficiency (%) 100 Mean Mean 41.07 41.07 160 RMS RMS 23.57 23.57 100 99.5 3 0 0 140 Underflow Underflow 99 202 202 99.8 Overflow Overflow 120 χ χ 2.5 2 2 / ndf / ndf 199.8 / 131 199.8 / 131 98.5 100 ± ± 930.5 930.5 18.14 18.14 99.6 Constant Constant pitch 20 small diode chip 1 Seed Charge Cut (ADC) 98 80 ± ± pitch 30 small diode chip 1 MPV MPV 26.27 26.27 0.188 0.188 Seed > 6 2 pitch 40 small diode chip 1 Seed > 7 ± ± 99.4 6.521 6.521 0.1017 0.1017 97.5 60 Sigma Sigma Seed > 8 pitch 20 small diode chip 3 Seed > 9 pitch 30 small diode chip 3 40 97 Seed > 10 1.5 99.2 pitch 40 small diode chip 3 Seed > 11 20 Seed > 12 96.5 0 99 1 0 0 20 20 40 40 60 60 80 80 100 100 120 120 140 140 -20 -10 0 10 20 30 40 -6 -5 15 20 25 30 35 40 45 -4 10 10 10 o Fake rate per pixel Pitch (microns) Temp ( C) Signal/Noise Signal/Noise CLIC–WS07, –8–
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