ATLAS/CMS Upgrades
Yasuyuki Horii
Nagoya University
on Behalf of the ATLAS and CMS Collaborations
/26Outline
LHC/HL-LHC plan
ATLAS/CMS upgrades
Physics prospects
2
LHC/HL-LHC Plan
/26Overview 4
SM precision studies and BSM searches with 13-14 TeV and 3000 fb-1.
Peak instantaneous luminosity: 5-7x1034 cm-2s-1 — a lot of challenges.
Two upgrade phases: Phase 1 (2019-2020) and Phase 2 (2024-2026).
http://hilumilhc.web.cern.ch/about/hl-lhc-project
/26Luminosity levelling 5
Lower pileup in the experimental detectors
Lower energy deposition by the collisions in the interaction region magnets
The average luminosity is almost the same.
HL-LHC is designed to operate with levelling.
CERN-ACC-2015-0140
ATLAS/CMS Upgrades
/26Challenges 7
Increased luminosity provides a significant challenge for the experiments.
Upgrades are essential to exploit the full potential of LHC and HL-LHC.
Higher radiation dose
Higher pileup
Higher particle rate
Higher event rate
Replacement of some of the detectors
Replacement of the electronics
Overall modifications
on the trigger and readout scheme
→
/26Inner tracker 8
Inner trackers will be in an extreme environment at HL-LHC. 1 MeV neutron equivalent fluence up to 2 x 1016 /cm2.
Ionisation dose up to 10 MGy.
Particle rates up to 2 GHz/cm2 — high occupancy, high bandwidth.
CERN-LHCC-2015-010; LHCC-P-008
Pileup 140 expected at L = 5 x 1034 cm-2s-1
CMS ATLAS
CMS
/26Inner tracker 9
CERN-LHCC-2012-022; LHCC-I-023. CERN-LHCC-2015-020; LHCC-G-166.
Phase 2 ATLAS
Channel occupancy [%] for 200 pileups
Ratio of reconstructed to generated tracks
Entire tracker replacement (all-silicon tracker) at the Phase 2 upgrade.
Radiation tolerance, increased granularity, reduced material, extension to forward, …
No pileup dependence with ≧ 11 hits
Pixel thickness possibly 150 µm, pixel size possibly 50 x 50 µm2
/26Inner tracker 10
Pixel detector replacement in the end of 2016 (as a Phase 1 project).
Entire tracker replacement at the Phase 2 upgrade.
Radiation tolerance, increased granularity,reduced material, extension to forward, …
CERN-LHCC-2015-010; LHCC-P-008
Pixel
Pixel +Strip
Strip
Pixel size considered: 25x100 µm2 and 50x50 µm2
CMS Phase 1/2
/26Calorimeter 11 CMS Phase 2
Endcap calorimeter will be replaced — longevity and performance issues.
CERN-LHCC-2015-010; LHCC-P-008
Frac
tion
of th
e re
spon
se
Hadron fluence 2 x 1014 /cm2 at |η| = 2.6. Defects in lead tungstate scintillating crystal of the electromagnetic calorimeter.
Response degradation also expectedfor the hadron calorimeter.
Light transmission loss
A high-granularity sampling calorimeter with a tungsten/silicon electromagneticpart (EE) followed by brass/silicon (FH) and brass/scintillator (BH) hadronic parts.
High performance at high pileup
/26Muon spectrometer 12
CERN-LHCC-2013-006; ATLAS-TDR-020
Micro-mesh gaseous detector (MM)
ATLAS Phase 1
New Small Wheel will be installed to cope with a relatively high hit rate(~15 kHz/cm2 at L = 7 x 1034 cm-2s-1) and also to improve muon trigger.
Both MM and sTGC for precision tracking and trigger.
Position resolution per layer: ~100 µm.
Segment angle resolution at first-level trigger: ~1 mrad.
Coverage: 1.3 < |η| < 2.7.
/26Trigger 13
More luminosity — more interesting events but also more background.
Without changes, trigger rates exceed the limits of trigger/readout system.
Simply increasing the threshold would kill the signal.
CERN-LHCC-2012-022; LHCC-I-023. CERN-LHCC-2015-019; LHCC-G-165. CERN-LHCC-2015-020; LHCC-G-166.
Choice of ATLAS and CMS at Phase 2 upgrades
Increase trigger rates. First level: ~100 kHz → 750-1000 kHz Storage level: ~1 kHz → 5-10 kHz
Increase latency — improve algorithm. First level: ~3 µs → 6-12.5 µs
Electronics replacements for all sub-systems.
CMS ATLAS
/26Trigger 14
Track trigger implementation in the first-level trigger.
Benefits: improved pT determination, better identification of charged leptons, …
Technologies: studies ongoing for Associative Memories, FPGA, …
Electron trigger
CERN-LHCC-2015-010; LHCC-P-008.
Muon trigger
CMS Phase 2
/26Trigger 15
Calorimeter trigger upgrade Muon trigger upgrade
Higher granularity information provided at first-level trigger. Less sensitive to pileup.
Extend muon trigger acceptancein the barrel by additional chambers.
CERN-LHCC-2013-017; ATLAS-TDR-022-2013. O. Kortner, VCI 2016.
Current
Phase 1
Additional RPCs
Phase 2
Muon A x ε in barrel could be improvedfrom ~70% to ~95%.
Trigger rate reduction for e, γ, …
ATLAS
Physics Prospects — Examples
/26ttH 17
ATL-PHYS-PUB-2014-012
Direct probe of Higgs-top coupling.
Observation expected for ttH, H→γγ.
ATLAS expected: 8.2σ (3000 fb-1).
gg→H and H→γγ indirect (loops). [GeV]γγm
100 120 140 1600
200 Background subtracted eventsSignal Fit
100 120 140 160
Even
ts /
( 2 G
eV )
0
100
200
300
=14 TeVs, -1 L dt = 3000 fb∫ SimulationBackground Fit
ATLAS Simulation Preliminary
/26H→bb 18
ATL-PHYS-PUB-2014-011
[GeV]bbm50 100 150 200 250
Even
ts /
20 G
eV
0
10000
20000
30000
40000
50000
60000
70000
80000
90000 ATLAS Simulation Preliminary
> = 140µ <-1L dt = 3000 fb∫ = 14 TeV s > 200 GeVV
T1 lep., 2 jets, p
VH(bb)x10VZWWMultijettt
t, s+t-chanWtW+bbW+blW+ccW+clW+lZ+bbUnc.
Observation expected for VH, H→bb (V = Z or W).
ATLAS expected significance at 3000 (300) fb-1: 8.8σ (3.9σ).
[GeV]bbm50 100 150 200 250
Even
ts /
20 G
eV
0
500
1000
1500
2000
2500ATLAS SimulationPreliminary
> = 140 µ, <-1 = 14 TeV, 3000 fbs
2 lep, 2 jets, 2 tags, > 200 GeVTZp
ZH x 10DibosonttZ+bbZ+blZ+ccZ+clZ+lUnc.
Access to Higgs-bottom coupling.
/26H→µµ 19
CERN-LHCC-2015-010; LHCC-P-008. ATL-PHYS-PUB-2013-014.
Reduction of the material and betterspacial resolution for tracking at Phase 2. Mass resolution expected:40% better with respect to ‘Phase 1 aged’(radiation damage for 1000 fb-1 assumed).
Observation expected for H→µµ.
ATLAS expected: 7.0σ (3000 fb-1).
Access to Higgs-muon coupling.
[GeV]µµm80 100 120 140 160 180 200
Even
ts /
0.5
GeV
210
310
410
510
610
710
810
910
1010 ATLAS Simulation Preliminary
-1dt = 3000 fb L ∫
= 14 TeVs=125 GeV
H, mµµ →H
µµ →Z
ttνµνµ →WW
[GeV]µµm100 110 120 130 140 150 160
(Dat
a - B
ackg
roun
d) /
0.5
GeV
-5000-4000-3000-2000-1000
010002000300040005000
ATLAS Simulation Preliminary = 14 TeVs
-1dt = 3000 fb L ∫
S+B toy Monte Carlo
S+B model
B-only model
/26Higgs couplings 20
)YκXκ(∆=XYλ∆
0 0.05 0.1 0.15 0.2 0.25
)Zγ(Zλ
Zγλ
gZλ
Zµλ
Zτλ
bZλ
tgλ
WZλ
gZκ
ATLAS Simulation Preliminary = 14 TeV:s -1Ldt=300 fb∫ ; -1Ldt=3000 fb∫
ATL-PHYS-PUB-2014-016. arXiv:1307.1347 [hep-ph].
For various coupling scale factor ratios,the precision of % level expected at 3000 fb-1.
Similar precision expected for ATLAS and CMS.
Fit with a fully generic parametrisation
No assumption on the total width
κgZ (= κgκZ/κH) overall scale parametercommon to all signal channels
No assumption on new particle contributionthrough loops
Hashed areas: current theory systematic uncertainties
/26Higgs couplings 21
CERN-LHCC-2015-019; LHCC-G-165
Significant improvement expected with 14 TeV, 3000 fb-1. Precision test of Yukawa terms for various ‘flavors’: t, b, τ, and µ.
mass (GeV)0.1 1 10 100
1/2
or (
g/2v
)λ
-410
-310
-210
-110
1WZ
t
bτ
µ
68% CL
CMSProjection
(14 TeV)-13000 fb
/26Bs,d→µµ 22
Some of new physics scenariosmay boost the Bs,d→µµ decay rates.
Bs/Bd ratio provides a stringent testof various models beyond SM.
B (Bs→µµ) = (3.65 ± 0.23) x 10-9
B (Bd→µµ) = (1.06 ± 0.09) x 10-10
C. Bobeth, et al., PRL 112, 101801 (2014)
Bs,d→µµ decays are only proceedthrough FCNC processesand are highly suppressed in SM.
B (Bs→µµ) = (2.8+0.7-0.6) x 10-9
B (Bd→µµ) = (3.9+1.6-1.4) x 10-10
D. M. Straub, arXiv:1012.3893
B (Bs→µµ) = (0.9+1.1-0.8) x 10-9
B (Bd→µµ) < 4.2 x 10-10 (95% CL)
CMS and LHCb, Nature 522, 68 (2015)
ATLAS, arXiv:1604.04263 [hep-ex]
/26Bs,d→µµ 23
(GeV)µµm4.9 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9
S/(S
+B) W
eigh
ted
Even
ts /
( 0.0
2 G
eV)
0
20
40
60
80
100
120CMS Simulation
)|<1.4µ(η|datafull PDF
-µ+µ→sB-µ+µ→dB
combinatorial bkgsemileptonic bkgpeaking bkg
-1Scaled to L = 300 fb
(GeV)µµm4.9 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9
S/(S
+B) W
eigh
ted
Even
ts /
( 0.0
1 G
eV)
0
100
200
300
400
500 CMS Simulation
)|<1.4µ(η|datafull PDF
-µ+µ→sB-µ+µ→dB
combinatorial bkgsemileptonic bkgpeaking bkg
-1Scaled to L = 3000 fb
300 fb-1 3000 fb-1
σ x B predicted by SM assumed.
B (Bs→µµ) precision: 13% B (Bd→µµ) precision: 48% (2.2σ)
B (Bs→µµ) precision: 11% B (Bd→µµ) precision: 18% (6.8σ)
CERN-LHCC-2015-010; LHCC-P-008. K. F. Chen, EPS-HEP 2015.
/26Bs→J/ψφ 24
ATL-PHYS-PUB-2013-010. PRD 91, 073007 (2015).
Luminosity 250 fb-1 3000 fb-1
σ(φs) (Stat.) 0.064 rad 0.022 rad
) [GeV]0s(B
Tp
0 10 20 30 40 50 60 70 80
) [ps
]0 s
(B τσ
00.020.040.060.08
0.10.120.140.160.180.2
> = 20µATLAS 2012 <> = 60 µIBL Layout, <> = 200 µITK Layout, <
ATLAS simulationPreliminary
Run 1
Run 2, …
CP violation due to interference betweendirect decay and decay with Bs-Bs mixing.
New physics can show up in the mixing.
Phase difference between interfering
amplitudes φs extracted from decay time
defined on the transverse plane: .
Improve decay time resolution στ by 30% with respect to Run 1 at ATLAS.
0 0_
φs = -0.0365 rad+0.0013-0.0012
SM global fit by CKMfitter
Bs
Bs
J/ψφ0_
0
Method improvement in arXiv:1601.03297 [hep-ex].
/26t→qγ, qZ, and qH 25
ATL-PHYS-PUB-2013-007. ATLAS-PHYS-PUB-2013-012. CMS PAS FTR-13-016.
FCNC top quark decays are highly suppressed in SM: B < 10-13.
New physics scenarios may enhance the rate up to B ~ 10-4.
HL-LHC expected limits at 95% CL are B = 10-4–10-5.
)γ q→BR(t
-510 -410 -310 -210 -110 1
qZ)
→BR
(t
-510
-410
-310
-210
-110
1
LEP
(q=u only) ZEUS
(q=u only) H1
D0
CDF
)-1ATLAS (2 fb
)-1CMS (4.6 fbATLAS
preliminary (simulation)extrapolated to 14 TeV:
-1300 fb(sequential)
-13 ab(sequential)
-13 ab(discriminant)
95% C.L.EXCLUDEDREGIONS
)4 cH) (x10→Br(t 1 1.5 2 2.5 3
SC
L
-310
-210
-110
1ATLAS Preliminarys = 14 TeV√, -1L dt = 3 ab∫
cutsT
Expected, tight jet p cuts, conservative bkg
TExpected, tight jet p
cutsT
Expected, loose jet p cuts, conservative bkg
TExpected, loose jet p
95%
/26Conclusion 26
Aim for SM precision studies and BSM searcheswith 300 fb-1 (LHC) and 3000 fb-1 (HL-LHC) at ATLAS and CMS.
Potential observation of the processes related with ‘flavors’:ttH, H→bb, H→µµ, Bd→µµ, …
Potential CP-violation measurement of Bs→J/ψφ, …
Increased luminosity (5-7 x 1034 cm-2s-1) provides a significantchallenge for the experiments.
High radiation dose, pileup, particle rate, and event rate.
Overcome the difficulties by the upgrades in various aspects.
Backup Slides
/26Calorimeter 28 ATLAS Phase 2
Maintain required performance under HL-LHC conditionsand therefore do not need replacement with possible exception for FCal.
FCal replacement with high-granularity one (100 µm gap) under discussion.
Addition of timing detector (intrinsic resolution O(10) ps) under discussion.
LAr: radiation hardness
CERN-LHCC-2015-020; LHCC-G-166
/26Calorimeter 29 CMS Phase 2
Radiation dose at 3000 fb-1 for the scintillating tiles of the endcap hadron calorimeter will reach up to 300 kGy— response degradation expected.
CERN-LHCC-2015-010; LHCC-P-008
For the new endcap calorimeter, exploit advances in silicon detectors in terms of cost per unit areaand radiation tolerance. The silicon sensors to be usedwill be simple, large area, andsingle-sided.
/26Muon spectrometer 30
CERN-LHCC-2013-006; ATLAS-TDR-020
• Current drift tube chambers: inefficiency and resolution degradationwith hit rate above 300 kHz/tube.
• Impact on the endcap inner layer with L > 1034 cm-2s-1.
ATLAS
/26Muon spectrometer 31 CMS Phase 2
(i) new irradiation tests must be performed to confirm that all types of existing muon detectors will survive the harsher conditions.(ii) additional muon detectors in the forward region 1.6 < |η| < 2.4 to increase redundancy and enhance the trigger and reconstruction capabilities.(iii) extension of muon coverage up to |η| = 3 or more behind the new endcap calorimeter to take advantage of the pixel tracking coverage extension.
Possible additional chambers GEM — micro-pattern gas amplification detector RPC — time resolution of ~100 ps for pileup mitigation
CERN-LHCC-2015-010; LHCC-P-008
/26Higgs couplings 32
Scenario 1: all systematic uncertainties unchanged.
Scenario 2: improved theoretical/systematic uncertainties.
CERN-LHCC-2015-010; LHCC-P-008. ATL-PHYS-PUB-2014-016.
iy
-310
-210
-110
1 Z
W
t
b
τ
µ
ATLAS Simulation Preliminary
= 14 TeVs
νlνl→WW*→4l, h→ZZ*→, hγγ→hγZ→, hµµ→bb, h→, hττ→h
]µκ, τκ, bκ, tκ, Wκ, Zκ[
=0i,uBR
-1dt = 300 fbL∫-1dt = 3000 fbL∫
[GeV]im
-110 1 10 210R
atio
to S
M
0.80.9
11.11.2
/26Bs,d→µµ 33
• Without trigger upgrade,
unsustainable event rate at HL-LHC.
• Track trigger with upgraded CMS
detector plays an essential role.
• Invariant mass mµµ resolution at
Level-1 trigger expected: ~70 MeV.
• Level-1 trigger rate expected:a few hundred Hz (<< 1 MHz).
(GeV)µµm4 5 6
Even
ts /
(0.0
2 G
eV)
1
10
210
310
410
510
610
710
810 CMS Simulation
-µ+µ→sB-µ+µ→dB
Background
Total signal
-1Scaled to L = 3000 fb
L1TrkMu (PhaseII) Trigger) > 3 GeVµ(
Tp
)| < 2µ(η|) > 4 GeVµµ(
Tp
)| < 2µµ(η|)| < 1 cmµµ(z d∆|
) < 6.9 GeVµµ3.9 < m(
at Level-1 trigger
CERN-LHCC-2015-010; LHCC-P-008. K. F. Chen, EPS-HEP 2015.
/26Bs→J/ψφ 34
Opposite-side tagging studied and calibratedby B±→J/ψK± (flavor provided by kaon charge).
Di-muon trigger with pT > 11 GeV (both muons)assumed at ATLAS at HL-LHC.
Systematic error of Run 1 analysis:
uncertainties in flavor charge tagging,
likelihood fit modelling,
trigger efficiency determination,
contribution of B→J/ψK* decays,
inner tracker alignment
— will benefit from the larger data samples.
ATL-PHYS-PUB-2013-010
Number of reconstructed PV
0 10 20 30 40 50 60 70 80 90 100
) [ps
]0 s
(B τσ
00.020.040.060.08
0.10.120.140.160.180.2
> = 20µATLAS 2012 <
> = 60 µIBL Layout 11,11 <
> = 200 µITK Layout 11,11 <
ATLAS simulationPreliminary
Run 1Run 2, …
Slight στ increase (14%) in Run 2 with number of primary vertices — but stable at > 40.
/26t→qH 35
arXiv:1509.06047v2 [hep-ex]
Current 95% CL upper limit on the branching ratio at the order of 10-3.
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