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ATLAS Phase II For the High Luminosity LHC. IPRD13 – Sienna Italy 07/10/2013. Dr. B. Todd Huffman on behalf of the AT LAS Collaboration ( Oxford University, United Kingdom ) . Ladies and gentlemen , I think we’ve got it !. CERN, 4 July 2012. - PowerPoint PPT Presentation
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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
CERN
, 4 Ju
ly 2
012
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
B.Todd Huffman 5
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
• Conclusions07/10/2013
B.Todd Huffman 6
What we mean by “Phase 2” Upgrade schedule2009201020112012201320142015201620172018201920202021202220232024 …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
~3000 fb-1
>=300 fb-1
>=75 fb-1
~25 fb-1
LS3
LS2
07/10/2013
7
Detector ChallengesPeak 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
8
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
9
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
B.Todd Huffman 11
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
12
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 coil cryost
at wall
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
B.Todd Huffman 13
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 detector5 barrel layers, 3x short strips (23.8 mm) and 2x long strips (47.8 mm)Strip Pitch – 74.5 mmStave-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
16
Barrel strip stave
Outer pixel stave Pixel disk EC strip petal
B.Todd Huffman 17
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
B.Todd Huffman 18
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
B.Todd Huffman 19
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
20
Trigger Evolution – Phase-II• L0 : 500kHz o/p rate • L1 : 200kHz o/p rate
– Addition of Track information (L1Track) in Regions of Interest (RoI)
21
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
22
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
caseMuon 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
B.Todd Huffman 23
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
24
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
B.Todd Huffman 25
BONUS MATERIAL
07/10/2013
Strip staves
26
B.Todd Huffman 27
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
B.Todd Huffman 28
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.
B.Todd Huffman 29
HL-LHC Fluences at z=0
07/10/2013
Strip staves
30
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)
31
Hybrids
DC-DC converter board
Example:DC-DC powered
stavelet4 modules
8 hybrids160 ABCn
20k channels
32
ATLAS Strip Read-Out(Barr
el and Forward)
HCC HCC HCC
GBTx VTRxOn-Detector
Off-Detector: COTS
Custom Rad-hard
Optical engines: TX: Laser driver + laser arraysRX: 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