B.Todd Huffman 1

ATLAS Phase IIFor the High Luminosity LHC

IPRD13 – Sienna Italy07/10/2013

07/10/2013

Dr. B. Todd Huffmanon behalf of the ATLAS Collaboration

( Oxford University, United Kingdom )

B.Todd Huffman 2

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Ladies and gentlemen,I think we’ve got it!

Discovery of a Higgs-like particle coupling to gauge bosons07/10/2013

B.Todd Huffman 3

Precision measurements of Higgs couplings

07/10/2013

ttH (with H γγ)• Allows precise measurement of top-Yukawa

coupling• Cleanest signal (w.r.t WH/ZH) S/B ~20% • S/√B ~6 with 3000 fb-1 (x2 better than 300 fb-1)

Final states targeted to measure couplings (that have low signal rate at LHC):

B.Todd Huffman 4

Physics at HL-LHC

• Is this “Higgs” really THE Higgs??• Also rare decays of known states (like

top quarks)• Energy upgrade imminent!!

– New states of matter to be found?• SUSY, Hidden SUSY, Z-prime, etc…

• Highly exciting time!

07/10/2013

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Outline High-Luminosity• Detector challenges

– Radiation damage– Background rates

• Tracking – Rad. studies; choice of detector technology– Detector design concepts (baseline)

• Trigger– HL-LHC studies on electrons and muons– Tracking ROI trigger

• Conclusions

07/10/2013

B.Todd Huffman 6

What we mean by “Phase 2” Upgrade schedule

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

2019

2020

2021

2022

2023

2024

…

2030?

LHC startup, √s= 900 GeV√s=7~8 TeV, L=6×1033 cm-2 s-1, bunch spacing 50 ns

Go to design energy, nominal luminosity √s = 13~14 TeV, L ~ 1×1034 cm-2 s-1, bunch spacing 25 nsPhase-0

Injector and LHC Phase-1 upgrade to full luminosity √s = 14 TeV, L ~ 2×1034 cm-2 s-1, bunch spacing 25 ns Phase-I

HL-LHC Phase-2 upgrade, IR, crab cavities √s = 14 TeV, L = 5×1034 cm-2 s-1, luminosity levelingPhase-II

LS1

~3

00

0 fb

-1>

=3

00

fb-1

>=

75

fb-1

~2

5 fb

-1

LS3

LS2

07/10/2013

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Detector Challenges

Peak luminosity (leveled) 1 to 5x1034cm-2s-1; 3000 fb-1

• Higher trigger rate need improved triggers rather than simply raising thresholds globally

Multiple interactions per crossing <140>• Higher detector occupancy • Increasing reconstruction complexity

Increasing fluences >1016neq/cm2 close to the beam pipe• Increased radiation damage • Increased activation of materials

Aging electronics (obsolete technology)

Baseline of the future Inner Detector traversed by an event with 230 Pile Up

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Phase-II: 2021/2022 (LS3)

ATLASdetector upgrade

• Replacement of the entire Inner Detector

• LAr and Tile calorimeter electronics upgrades• Possible upgrade of Forward Calorimeters • Upgrade of Muon system

• Muon Barrel and Large Wheel trigger electronics

• Possible upgrades of TGCs in Inner Big Wheels• Coping with a track trigger

• Forward detector upgrade• Target Absorber Secondaries (TAS) and shielding upgrade• TDAQ upgrade• Software and computing• Various infrastructure upgrades• Common activities (installation, safety, …)

18 month shutdown

Phase-II LoI: https://cds.cern.ch/record/1502664?ln=en

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The Detector Challenges roughly Split into Two Parts

07/10/2013

>1m radius Pile-up & Trig. Rates;

all of the detectors butwill show upgrades forMuons and Electrons

<1m radius Radiation Damageto components; ITK expected fluence at 14 TeV (3000 fb-

1 )

ATLAS Inner Tracker (ITK) region

Sensor Rad. Damage Studies

A. Affolder – VERTEX 2011 10

All studied n-strip readout substrates become more and more similar with irradiation. This is true after neutron, proton and pion irradiations and with Hamamatsu and Micron devices.

UnannealedNeutrons

900 V

Micron Neutrons: A. Affolder, et. al., Nucl. Instr. Meth. A, Vol. 612 (2010), 470-473.Micron 26 MeV Protons: A. Affolder, et. al., Nucl. Instr. Meth. A, Vol.623 (2010), 177-179.

HPK Neutrons: K. Hara, et. at., Nucl. Inst. Meth. A, Vol. 636 (2011) S83-S89. HPK 26 MeV Protons: New and unpublished

900 VUnannealed26 MeV Protons

RD50

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All Silicon Inner Tracker (ITK)

• n-in-p advantages– Single-sided process (less expensive)

• n+-in-n detectors– Double-sided (more expensive)– Guard rings @ ground near amplifiers

• Both can work at HL-LHC rad. Levels – (If carefully designed)…– (And if they are kept cold ~-20o C)

07/10/2013

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All Silicon Inner Tracker for HL-LHCClassical layout with barrel cylinders and endcap disks – “Utopia”

establishes baseline performance and cost • no special triggering layers

long strip layers

short strip layers

IP pixel layers beam pipe

solenoid coilcr

yost

at w

all

total of 14 hits with full coverage to η=2.5 • Pixels to η<2.7 (forward muon ID)

Strips (74M channels)

• 5 barrel layers + 7 fwd disks• stub layer for overlap region • 2 Si sensors at 40mrad stereo

angle

Pixels (638M channels)

• 4 barrel layers + 6 fwd disks• inner 2 layers replaceable: 25μm x 150μm• outer Pixel: 50μm x 150μm• sensors bump bonded to readout

chip using 65nm CMOS technology

stub cylinder

minimize gaps in coverage• last strip disk at z=3m, last pixel layer at 25-30cm (improve double track resolution)• small “stub” layer in barrel

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Est. Hit occ. (Everywhere < 1%)

07/10/2013

Simulations indicate no problems with pattern rec. at these levels.(note: 200 events pile-up for this study)

Hit Occ. in %

Pixel staves

Pixel module

Pixel module

Outer facesheet

Carbon foam

Flange

Web

Cable

Close-out

Outer coolant tube

Inner facesheet

Inner coolant tube

Cable

38 m

m

• Outer pixel layers– About 1.4m long and 5mm thick– Modules on both sides, overlap for full

coverage, makes module mounting easier

– n-in-p sensors (less costly)

• Inner pixel layers– I-beam design linking

neighbouring layers; Clamshell construction

– Optimizes stiffness

– n+-in-n sensors

B.Todd Huffman07/10/201315

Need ~20000 of these ….

Phase2: Barrel Strip-Tracker

Strip barrel detector

5 barrel layers, 3x short strips (23.8 mm) and 2x long strips (47.8 mm)

Strip Pitch – 74.5 mm

Stave-concept construction

Slide in – more reliable installation

Fully incorporated det. Services

End of Stave card

Tracker elementsConcept:To create integrated, fully functional objects, which can be

– Produced in parallel– Tested fully early in the assembly– Single staves are of limited value and loss

of small number has small impact on project

→ Project robustness

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Barrel strip stave

Outer pixel stave Pixel disk EC strip petal

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Radiation tracker components• Optical data link

– 4.8 Gbps– “Versatile link”

• Pixels Micro-cables to escape highest Rad. zones– ~4m along the beam line– Then switch to optical

readout

• Strips Versatile Link

07/10/2013

GaAs

InGaAs

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Inner Tracker Summary

• Rad. Damage Studies show good performance for n-implant silicon detectors. – Cost considerations mainly driving decision to use n-

in-p for Strips and outer pixels

• Tracking coverage and hit occ. maintained.• Novel support structures under design

– Stave concept– Cooling requirements mean Services (cooling,

monitoring, control) incorporated into support structure.

• Rad-hard and SEU tolerant Gbps readout systems needed

07/10/2013

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Part II: Increased Trigger rates

• L0 added @ 500 KHz rate• L1 moves to 200 KHz rate• Important!: Maintain 20 GeV threshold

muons (sharpen it up) and elec. (add tracks)• ROI seeded Tracks at L1, regional triggers

• ROI = Region of Interest

• Incorporated in FE electronics chips• Leads to trigger and electronics upgrades

like muon system (but most sub-detectors need some upgrades)

07/10/2013

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Trigger Evolution – Phase-II• L0 : 500kHz o/p rate

• L1 : 200kHz o/p rate– Addition of Track information (L1Track)

in Regions of Interest (RoI)

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Muon Triggers

Rates for 20 GeV pT threshold @ 3x1034 cm-2s-1:• No change: 50kHz• All Phase-1 upgrades except NSW : 30 kHz• Adding NSW: 13 kHz

Phase-1: • Additional Thin Gap

Chamber (TGC) doublets (EIL4)

• Include information from Tile Extended Barrel

Phase-2:• New Small Wheel (NSW):

Vector tracking based on sTGC and Drift tubes

• Reject b.g. from n & g• Reduce fake muons

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L1Track• Maintain single lepton trigger thresholds at ~20GeV by adding track information

at L1• ~factor 5 rejection with 95% efficiency for offline selected events w.r.t. no L1track

case

Muon Trigger MU20: require track pT>15GeV in DR<0.15

Electron trigger:Require track in DR<0.150.67< E/p < 1.5=> Factor ~10 rate reduction

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Sharpening Trigger rates

07/10/2013

¤ Shown is a simple Power-law falling spectrum – Backgrounds fall faster(Red-Dashed)

¤ Idealized Trigger turn-on is made sharper in right-hand case(Solid Green)

¤ Events that Pass Trigger – (Solid Blue)¤ ~4.5 times reduction in rate in right-hand case¤ In actual muon trigger, expect a factor of two reduction in rate.

1/E6

90% efficient

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CONCLUSIONS Higgs Discovery motivates luminosity upgrade of LHC. Proposed machine upgrade for Phase II (circa 2022) presents great challenges for the ATLAS detector.

Direct Radiation Damage and SEU’sIncreased backgrounds (pile-up events)

Shown how these are addressed in the Inner Tracker and the lepton triggers (obviously much more work is taking place in other sub-systems in parallel).

We should have an excellent detector during the next decade’s exciting discoveries!

THANK YOU. 07/10/2013 B.Todd Huffman

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BONUS MATERIAL

07/10/2013

Strip staves

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Strip forward Detector

• 7 Disks• Different types of

modules– “Petal” concept

• Continue tracking coverage |h|<2.7

• “Petalet” sub-unit under construction.

07/10/2013

Petalet

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Stave Concept – Barrel

07/10/2013

Barrel strip stave insertion and locking mechanicsSingle-edge Mounting schemeStaves “slide in” from end of barrelRunning theme Throughout inner tracker – Services incorporated in support structures.

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HL-LHC Fluences at z=0

07/10/2013

Strip staves

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Strips electronics & readout(prototypes – close packed text: G. Viehhauser)

• Sensors: n-in-p single sided design, 98 x 98mm2, 500V Max• Hybrids: glued onto sensor• ASICs: a 130 nm CMOS chipset

– ABCn130: binary readout architecture (like SCT) but new protocol, 256 inputs for smaller hybrids, ROI and fast L1 trigger block

– HCC: interface and module controller (1 per hybrid)• LV Powering: either serial (SP) or DC-DC at each

hybrid/module– Additional powering and protection chipset, prototyped and new

versions in development

• Readout is being tested using stavelets (goal: good noise performance)

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Hybrids

DC-DC converter board

Example:DC-DC powered

stavelet4 modules

8 hybrids160 ABCn

20k channels

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HCC HCC HCC

GBTx VTRx

On-Detector

Off-Detector: COTS

Custom Rad-hard

Optical engines:

TX: Laser driver + laser arrays

RX: p-i-n array + TIA/discriminator

GBTx functionality in FPGA

B.Todd Huffman 33

Radiation tracker components

07/10/2013

Responsivity of Photodiodes:Tough power budget decisions

Makes Optical links unattractive choice at Pixel radii.

GigaBit Transmitter (GBTX)Custom chipMultiplexer w. Forward Error correction(for Single Event Upset mitigation)

SEU tests show they come in bursts. FeCcan correct up to 16 bits in a row.

Data scrambled (helps DC balance)

Why Upgrade?

Physics case: European Strategy Meeting (Sept. 2012, Kracow) http://indico.cern.ch/conferenceDisplay.py?confId=182232

Physics programme at LHC only begun with √s= 7-8 TeV collisions

After 4th July 2012…

Higgs boson precision measurements• Expected uncertainties on signal strength reduced by a factor of 2-3 with HL-LHC• Ratio of partial widths to measure ratios of couplings and probe new physics at 5-15% level

Higgs self-coupling in SM becomes accessible only at HL-LHC luminosity

Probing new Physics• SUSY and other New Physics beyond SM• Enhancements in vector boson scattering amplitudes• Rare processes such as FCNC decays of top accessible to 10-5