The Physics Program of
the High Luminosity LHC
and Beyond
Brian Petersen
5 January 2017
The 3rd KMI International SymposiumIntroduction
Higgs discovery huge successfor the LHC program
Detailed measurementsof its properties in progress
So far appears consistent
with SM predictions

Searches for BSM signals
so far negative and arequite constraining
However, to achieveultimate possible precisionmuch more luminosity
needed in many cases

Strong motivationfor High-Luminosity LHC

2

arXiv: 1606.02266

3

HL-LHC UpgradeHL-LHC Planning
LHC to deliver 300 fb-1 by 2023 (end of Run-3)
HL-LHC goal is deliver 3000 fb-1 in 10 years
Implies integrated luminosity of 250-300 fb-1 per year
Requires peak luminosities of 5-7x1034 cm-2s-1
while using luminosity leveling (3-5 hours at peak luminosity)
Design for “ultimate” performance 7.5x1034 cm-2s-1 and 4000 fb-1

4

HL-LHC Project5

Major intervention on more than 1.2 km of the LHC
New IR-quads Nb3Sn(inner triplets)
New 11 T Nb3Sn(short) dipoles
Collimation upgrade
Cryogenics upgrade
Crab Cavities
Cold powering
Machine protection...

Machine upgrade approved by CERN council in June 2016

The High-Luminosity Challenge

6

HL-LHC provides an extreme challenge to the experiments
Very high pile-up

Intense radiation levels

Major experiment upgrades needed to:
Improve radiation hardness and replace detectors at end-of-life
Provide handles for mitigating pile-up (high granularity, fast timing)
Allow higher event rates to maintain/improve trigger acceptance

Goal is to maintain or improve over current performanceDetector Upgrade – ATLAS
Calorimeters
New BE/FE electronics
New HV power supplies
Lower LAr temperature(Timing detector)
High granularity
timing detector
Coverage: 2.5<|η|<4.2
Possibly absorberfor |η|<3.2

Tracker
All silicon tracker (strip and pixel)
Radiation tolerant, high granularity
Low material budget
Coverage up to |η|=4

Muon System
New BE/FE electronics
New RPC layer in inner barrel
Muon-tagging in 2.7<|η|<4.0(under study)

7

Trigger and DAQ
L0 rate at ~ 1 MHz(latency up to 10 μs)
Possible hardware
L1 track trigger
HLT output ~10 kHz

Extended Silicon-based Tracker
ATLAS (and CMS) plan
to extend tracker coverageto η~4 with pixel extension
Provides multiple benefits
Extended lepton coverage(with forward muon tagger)
Forward b-tagging
Improved vertexing

Primary benefit ispile-up suppression
Possible support structures for large η pixel detector

8Muon System Upgrades

9

Readout electronics to be replaced everywhere to support
higher trigger rate and MDT hardware trigger
Power system to be replaced (maintenance and radiation issues)
RPCs added to inner station to increase acceptance/robustness

Will replacesome MDT
chambers
to makespace for
RPCs

Studying options forlarge η muon tagger

Possible
replacement of
low radius TGCs

Inner wheel is replaced in Phase-I

10

Higgs Physics at HL-LHC

Higgs program at HL-LHC
Higgs boson studies are a major component of
HL-LHC physics program
Main Higgs measurements at HL-LHC:
Higgs couplings
Rare Higgs decays
Higgs differential distributions
Higgs self-coupling
Heavy Higgs searches
Higgs Production Channels
3000 fb-1
HH ~100k

Higgs Decay Channels
3000 fb-1

11

Physics Projections
HL-LHC Physics prospects done in two ways:
Parameterized detector performance
Event-generator level particles smeared with detector
performance parameterized from full simulation andreconstruction of upgraded HL-LHC detectors
Effects of pile-up included for either 5x1034 cm-2s-1(140 pile-up events) or 7x1034 cm-2s-1 (200 pile-up events)
Analysis mostly based on existing 8 TeV analyses with simple
re-optimization for higher luminosity

Extrapolation of Run-1 or Run-2 results
Scale signal and background to higher luminosities
Correct for different center-of-mass energy
Assume unchanged analysis (not re-optimized for higher
luminosity)
Assume same detector performance as in Run-1/2(some use corrections based on studies in first approach)12

Projections for Higgs Couplings
Full set of HL-LHC coupling projections
are based on Run-1 analyses

ATL-PHYSPUB-2014-016

For μ=140 in case of ATLAS
Same as Run-1 performance for CMS

Higgs coupling precision (per experiment):
3-5% for W, Z and γ~7% for µ
5-10% for t, b and τ

Do not include improved detector designs
or improvements in analysis techniques
CERN-LHCC-2015-010

300 fb-1

3000 fb-1

13

Rare decays: H→µ µ and H→J/ψγ+ -14

Probes Higgs coupling to 2nd generation quarks/leptons
ATL-PHYSPUB-2013-014

H→μ+μBR(H→μ+μ-)=2.2x10-4 in SM
Combined Run-1 and Run-2 limit is 3.5xSM

Expect significance of ~2σ with 300 fb-1
and ~7σ with 3000 fb-1 in inclusive channel
Improved tracker resolution not accounted for(~30% improvement on mass resolution)
Also specific channels like ttH, H→μ+μATL-PHYSPUB-2015-043

H→J/ψγBR(H→J/ψγ)=2.9x10-6 in SM
ATLAS Run-1 limit at 95% CL: BR(H→J/ψγ)<1.5x10-3

Multivariate analysis for HL-LHC projection
With 3000 fb-1 will have just 3 signal eventsand 1700 background events-6
Expected limit at 95% CL: BR(H→J/ψγ)<(44+19-12)x10

Higgs Self Coupling

Measurement of Higgs pair production
major goal of HL-LHC program
Requires full HL-LHC luminosity to reach SM sensitivity
Allows for a measurement of self coupling λλExtremely challenging due to low cross section (SM: 40 fb)

15

HH→bbγγ Analysis
Low statistics, but high purity channel
After selections expect 8.4 signal eventsand 47 background events
Corresponds to signal significance of 1.3σ

16

ATL-PHYSPUB-2014-019

95% CL limits on self-coupling (ignoring systematics): -1.3<λ/λSM<8.7

HH→bbτ τ Analysis

17

+ -

Consider all combinations of leptonic/hadronic ττ final states:
Signal events: Background events:

Event yields for3000 fb-1 using
a cut-based
analysis strategy:
Signal significancefor SM coupling:m(τ+τ-)

m(bb)

95% CL limits on self-coupling: -4<λ/λSM<12

ATL-PHYSPUB-2015-046

HH→bbbb Analysis

18

HH→bbbb analysis dominated by large Run-2 m4j extrapolated to 3000 fb-1, 14 TeV
multi-jet background
ATL-PHYSPUB-2016-024
Very difficult to simulate
Instead extrapolate from Run-2
assuming unchanged performance
Multijet background is estimated fromcontrol regions (CRs)
Systematics uncertainty assigned
from CR differences
These will decrease with luminosity
ATL-PHYSPUB-2016-024

Neglecting systematics expect0.2<λ/λSM<7 at 95% CL
Best of the measurements
If assuming todays systematics:-3.5<λ/λSM<11 at 95% CL
Similar to HH→bbτ+τ-Search for ttHH Production

19

σ(ttHH) only ~1fb, but more handles to suppress backgrounds
Use HH→bbbb final state and semi-leptonic tt decay
Signature: 6 b-jets, 2 light jets, lepton and missing energy
Simple cut-based analysis
No cuts on Higgs candidate mass due to combinatorics
ATL-PHYSPUB-2016-023

ATL-PHYSPUB-2016-023

Selection with ≥5 b-tags:
25 signal events, 7100 background events
Background dominated by c-jets from W mis-tagged as b
Significance for ttHH production without systematics: 0.35σ

20Precision Measurements

Vector Boson Scattering

21

Vector Boson Scattering probes
the quartic gauge boson couplings
and EW symmetry breaking
Striking experimental signature of two forward jets
Provides additional motivation for forward tracker extension
Using leptonic decays clean observations on ZZ, WZ and
W±W± boson scattering
Sensitive to dimension-6/8 operators at TeV scale
Precision on SM W±W± boson scattering ~6% with 3000 fb -1

WZ→ℓνℓℓ

ZZ→ℓℓℓℓ

W±W±→ℓνℓν
LHCC-G-166

ATL-PHYSPUB-2013-006

ATL-PHYSPUB-2013-006

Flavor-Changing Neutral Currents in top

22Search for t→Zq and t→Hq Decays

23

Search for tt with one t→Wb decay and one FCNC t decay
Reconstruct as much as possible of top decays
to obtain maximal discrimination

ATL-PHYSPUB-2016-019

For t→Zq use kinematic χ2 fit
using leptonic Z decays:
Expected 95% CL limit assuming
equal t→Zu and t→Zc: ~2.5x10-5
ATL-PHYSPUB-2016-019

For t→Hq use H→bb andkinematic discriminant
Furthermore split in categories
based on reconstructed
topology (#jets, #b-jets, ...)
Expected 95% CL limit assuming
equal t→Hu and t→Hc: ~1.1x10-4

24

Beyond the Standard ModelSupersymmetry Production at LHC

25

Lightest neutralino normally assumed to stable (Dark Matter candidate)Search for Gluino Pair Production

26

In “natural SUSY” expect relatively light gluinos (~few TeV)
For example search in four jets+ET,miss channel for g→qqχ

ATL-PHYSPUB-2014-010

Expect to discovergluinos up to ~2 TeV for
neutralinos up to 1 TeV
Exclude gluinos
up to ~3 TeV

Search for Stop Pair Production

27

In “natural SUSY” also expect light stops (<~1 TeV)

Search for t→tχ in two scenarios:m(t) >> m(t)+m(χ) using both 0 and
1 leptonic top decaym(t) ~ m(t)+m(χ) (compressed)using 2 leptonic top decaysm(t) >> m(t)+m(χ)m(t) ~ m(t)+m(χ)
ATL-PHYSPUB-2014-010

For uncompressed stop, can discover up to 1.2 TeV
For compressed stop, only 0.5 TeV

ATL-PHYSPUB-2016-022

Search for Chargino-Neutralino Production

28

Projection for chargino-neutralino production in 2 channels:

ATL-PHYSPUB-2014-010

Discovery reach up to ~850 GeV

ATL-PHYSPUB-2015-032

Search for Stau Pair Production

29

Finally HL-LHC will have sensitivity to direct slepton production
Studied search for stau pairs
Require two hadronic tau
decays and large ETmiss
Final discriminant:mT(τ1,ETmiss)+ mT(τ2,ETmiss)For τL, expect to have 5σ discovery up to ~420 GeV,

ATL-PHYSPUB-2016-021

while even with 3000 fb-1, do not achieve 5σ sensitivity for τRSearch for Heavy Resonances30

New physics could be anywhere
Search for resonances in all final states
di-leptons, di-jets, di-top, di-bosons (γγ, WW, WZ, ZZ, hh)…
Only a few of these projected up to 3000 fb-1 so far
Many channels do not gain that much by more luminosity
as they are close to kinematic end-point
More luminosity most interesting if something seen before
Kaluza-Klein gluon excitation→tt

Kaluza-Klein graviton excitation→tt

ATL-PHYSPUB-2013-003
LHCC-G-166

Search for WIMP Candidates

31

ATLAS also has sensitivity to non-SUSY WIMP models
For example with canonicalmono-jet signature:

ATL-PHYSPUB-2015-015

Or invisible Higgs Boson decays:

ATL-PHYSPUB-2013-015

32

Future Circular Colliders

CERN is Studying Next Collider
Conceptual design studies ofcolliders in ~100 km ring
pp collider (FCC-hh)
Primary motivation for FCC studies√s~100 TeV, L~2x1035 cm-2s-1
4 IPs and 20 ab-1/expt
Also studying FCC-hh dipoles (16T) in
LHC tunnel (HE-LHC with √s~30 TeV)
e+e- collider (FCC-ee)√s~90-350 GeV, L~200-2x1034cm-2s-1
2 IPs and 20 ab-1/expt
pe collider (FCC-he):√s~3.5 TeV, L~1034 cm-2s-1
Goal: CDR for next European Strategy Decision (2019-2020)

Machine studies are site-neutral,
but FCC at CERN would greatly
benefit from existing laboratory
infrastructure and accelerators

33

Physics Program for FCC-hh

34

Main physics goals of FCC-hh
Directly explore energy range up to 50 TeV for New Physics
Conclusive exploration of EWSB dynamics
Give final verdict on heavy WIMP dark matter
Expected reach for supersymmetry
ArXiv:
1606.00947

Expected precision for di- and tri-Higgs
production and Higgs self-couplings:

Physics Program for FCC-ee
High-precision Higgs couplings
Indirect sensitivity to energy-scale of O(100 TeV)
through precision EW parameter measurements
Possible Higgs coupling precision

Current EW precision

Future EW precision?

Also mtop measured to ~10 MeV
precision from threshold scan

35

36

SummarySummary
High-Luminosity LHC very challenging environment,
but maximizes the physics output of the LHC project
Major detector upgrades planned for optimal performance
Should be as good or better than now in most areas
Precision Higgs measurements are the main physics driver for
HL-LHC and detector upgrades, but wide range of measurements
and Beyond Standard Models searches are possible
Technical Design Reports in preparation
and will come over the next ~1 year
Next generation colliders for the ultimate
studies of Higgs and multi-TeV New Physics
are under study at CERN
Conceptual Design Reports in ~2 years

Please stay tuned
Much more information in presentationsat HL-LHC Experiments workshop in
Aix-Les-Bains in October:
https://indico.cern.ch/event/524795/timetable/

37

38

BackupDetector Upgrades – CMS
Endcap Calorimeter
High-granularity calorimeterbased on Si sensors
Radiation-tolerant scintillator
3D capability and timing

39

Barrel Calorimeter
New BE/FE electronics
ECAL: lower temperature
HCAL: partially new scintillator
Possibly precision timing layer

Tracker
Radiation tolerant, high granularity
Low material budget
Coverage up to |η|=4
Trigger capability at L1

Trigger and DAQ
Muon System
New Be/FE electronics
GEM/RPC coverage in 1.5<|η|<2.4
Muon-tagging in 2.4<|η|<3.0

Track-trigger at L1(latency up to 12.5 μs)
L1 rate at ~ 750 kHz
HLT output ~7.5 kHz

Anomalous HZZ Coupling

40

CMS-DP-2016-064

Test for anomalous HZZ
couplings ai:

Interference contribution
becomes more dominant at
smaller values of fai x cos(φai)

Projections based on Run-2 Analysis
H→γγ and H→ZZ
projections updated
to 13 TeV (12.9 fb-1)
based Run-2 analyses
H→γγ added expecteddegradation at μ=200
Beamspot ~5cm
Vertex identification
reduced from 80% to 40%
Photon ID efficiency
decreased by
2.3% (10%) in EB (EE)

Theory uncertainties
become dominate at HL-LHC
Decouple by measuringfiducial cross section
Can achieve ~4%
precision

41

CMS-DP-2016-064

300 fb-1

3000 fb-1

Projections based on Run-2 Analysis

42

CMS-DP-2016-064

H→γγ and H→ZZ
projections updated
to 13 TeV (12.9 fb-1)
based Run-2 analyses
H→ZZ added expecteddegradation at μ=200

300 fb-1

3000 fb-1

Reduced lepton efficiency
Increased misidentification

Can make precise
differential pT(H)cross section
measurements

CMS-DP-2016-064

300 fb-1

3000 fb-1

Higgs to Invisible
Main backgrounds:
Z(ℓℓ)+jets
W(ℓν)+jets
QCD multijet
Current BR(H→inv) limit (expected):
BR<0.30 @ 95% CL (CMS)
BR<0.31 @ 95% CL (ATLAS)
Projected upper limit (CMS) as
as function of luminosity:

43

CMS-DP-2016-064

Summary of Recent ATLAS Higgs Results

44VBF H→ZZ*→ℓℓℓℓ
Initial selection:
2 jets with m(jj)>130 GeV

4 leptons consistent
with H→ZZ*→ℓℓℓℓ
Use BDR to separate ggF and VBF
Large pile-up contribution in ggF
190 signal events and330 background eventsResults with full systematics (signal QCD scale)and statistics only:

45
ATL-PHYSPUB-2016-008

Systematics Treatment
With large statistics at HL-LHC, systematics can be
dominating in measurement precision
Hard to predict how these will evolve with luminosity/time

Both experiments start from current systematics with aslightly different approach
ATLAS approach:Experimental systematics scaled to best guess for HL-LHC
Results provided with current theory systematics and without
theory systematics

CMS approach:
Provide results in two scenarios:
Scenario 1: Current experimental and theory systematics
Scenario 2: Experimental scaled with luminosity (1/√L) until
a certain best achievable uncertainty level
The current theory systematics is halved

Both approach aim to bracket the achievable precision46

Wanted Reduction in Theory Uncertainties

ATL-PHYSPUB-2014-016

47

Higgs Self Coupling Projections
ATLAS simulations (HH→bbbb is Run-2 extrapolations):
ChannelExpected limit in μ
Full
Syst.

Stat.
only

ATL-PHYSgg→HH→γγbb PUB-2014-019
ATL-PHYS-

gg→HH→ττbb PUB-2015-046 4.3
ATL-PHYS-

gg→HH→bbbb PUB-2016-024 5.2
ATL-PHYS-

ttHH→thadtlepbbbb PUB-2016-023

Significance

Limits on λ/λSM at 95% CL

Full
Syst.

Full Syst.

Stat.
only

1.3σ

-1.3<λ/λSM<8.7

0.6σ-4<λ/λSM<12

1.5-3.5<λ/λSM<110.35σ

CMS extrapolations from Run-2 analyses:
CMS-DP-2016-064

Stat. only

0.2<λ/λSM<748

Search for Heavy Higgs→ττ
One of the most sensitive
channels for constraining
extended Higgs
Cross section limits:
ggφ (→ττ)bbφ (→ττ)

300 fb-1

3000 fb-1

Model dependent limits:
mmod+ benchmark
Sensitivity at high mA is
still dominated by statistics

49

CMS Tracker Changes

50

CMS Tracker Comparison

51

ATLAS Tracker Hits and Material
Optimized for at least 13 hits,
minimum material and coverage
up to η=4

ATL-PHYSPUB-2016-025

ATL-PHYSPUB-2016-025

52

CMS Tracker Performance

53
CMS-DP-2016-065

ATLAS Tracker Performance

54
ATL-PHYSPUB-2016-025

B-tagging for HH→bbbb
Efficient and highly rejecting b-tagging also critical for
HH→bbbb measurement
Current projections assume performance as in Run-2
Both experiments have demonstrated ability to matchcurrent performance at pile-up of 140 events
Both pixel detectors still being optimized
Aim to achieve Run-2 performance at pile-up of 200
ATL-PHYSPUB-2016-026

Run-2

CMS-DP-2016-065

55

New CMS Endcap Calorimeter

56

ATLAS Trigger Schemes
Level-0 + Level-1 hardware trigger

57

Level-0 only hardware trigger

CMS Trigger System
Current Level-1 trigger uses only calorimeter and muon information
Phase-II upgrades
Replace calorimeter electronics
Increase latency and Level-1 accept rate

Use tracking at Level-1 based on doublet seeds
Global track-trigger correlator

58

ATLAS Example Trigger Menu
For most trigger channels, expect to maintain same or evenlower trigger threshold as in Run-1
Hadronic triggers challenging due to pile-up

59

CMS Example Trigger Menu
Menu without track-trigger
has 1.5 MHz rate μ=140
Track-trigger gives
factor 5.5 reduction:
260 kHzUse 1.5 safety factor:
390 kHz
Menu with track-trigger
has 500 kHz rate μ=200
With 1.5 safety factor:
750 kHz
Without track-trigger:~4 MHz60

CMS Precision Timing for Charged Particles

61

Assume sufficient timing performance for charged hadrons,e.g. from dedicated LYSO+SiPM layer in the central region,and from HGCAL or dedicated layer in the forward region
Traditional three-dimensional vertex fit can be upgraded to afour-dimensional fit, with vertices reconstructed both in position
along the beamline and in time within the bunch crossing
Provides further suppression of charged particles
from pile-up for jets, missing energy, lepton isolation etc
CMS-DP-2016-008

20 ps resolution
assumed for charged
particles with pT>1 GeV

Pile-up vs Pile-up Density

62

So far mostly considered effects due to overall pile-up
Find that many quantities depend more on
pile-up density – how many in pile-up collisions per mm in z
This can be mitigated by changing
B-tagging efficiency
beam-profile
I.e. spreading vertices
CMS-DP-2016-065
out better in z
Lepton isolation efficiency
IDTR-2016-012

Higgs Impact on Upgrade Design
The design of the upgraded HL-LHC detectors iscomplex process
Want ultimate performance, but limited by what canreasonably be upgraded during long shutdown and by cost

Higgs measurements are corner stone of the HL-LHC
physics program and they provide prime motivation formany upgrades beyond current detector capabilities
Will highlight four different cases:
Pile-up jet suppression in VBF Higgs production
H→γγ reconstruction with precision timing detector
H→ττ triggering
HH→bbbb triggering and reconstruction

63

Pile-up Jet Suppression
At 200 pile-up, every events has~5 pile-up jets (pT>30 GeV)Can suppress these by using
tracking to associate them toeither pile-up or hard-scatter vtx
For VBF Higgs productionneed to use jets out to η~4
Extended tracker enables this
CERN-LHCC-2015-010

64

CERN-LHCC-2015-020

JETM-2016-012

VBF H→WW→eνμν Analysis
Physics gain of forward tracker
studied in H→WW analysis
Simple cut based analysis:

65

ATL-PHYSPUB-2016-018

2 forward jets (|η|>2) in
opposite hemispheres
No jet above 30 GeV in between jetse/μ in between forward jets
Missing ET>20 GeV

After selection:~200 signal events~400 background events from tt and non Higgs WW

Signal precision and significanceTrackercoverage|η|<4.0|η|<3.2|η|<2.7

Different levelsof backgrounduncertainties
with respect toRun-1 H→WW
analysis

Factor two gain in precision from extended tracker coverage

High Granularity Timing Detector
Minimum bias
66

Additional pile-up rejection can
High-granularity scintillators
be achieved using precise timing
timing detector
Different time of flight anddifferent collisions times in event
ATLAS considering thin timing device
Four layers silicon sensors
Coverage for 2.4<|η|<4.2
Possible Tungsten absorber for |η|<3.2
Timing target: 30-50 ps per MIP
Provide additional sensitivity to VBF
Possibly also enhance the jet trigger
ATLAS LAr

Timing Detectors in CMS

67

Endcap calorimeter (1.5<|η|<3) replaced bymulti-layer silicon-based calorimeter
Current calorimeter not rad-hard enoughUse of silicon allows intrinsic time resolution
down to 50 ps for large signal
Barrel calorimeter electronics upgraded toalso provide precision timing (30 ps)
Additional timing layer for charged particles
in front of calorimeter under consideration

Allows to reconstruct vertex time
CMS-DP-2016-008

Example: Improved H→γγvertex association

CMS-DP-2016-008

H→γγ with Timing Detector
Vertex selection efficiency drops
with increase in pileup~80% now → ~40% at 200 pileup
Results in large degradationof mass resolution
Impact on fiducial crosssection measurement investigatedWith full use of calorimeterand charged particle timing
information vertexing efficiency
can be almost full recovered
Corresponds to effectively
30% more luminosity68

Triggering on H→ττ

69

H→ττ channel critical for understanding fermionic coupling
and measuring Higgs CP properties
Difficult to trigger on efficiently
Two narrow, fairly soft jets with 1-3 charged tracks
Existing calorimeter-only L1 triggers not sufficient
Acceptance drops quickly as thresholds are raised
Adding fast track trigger can give large rate reduction
CMS estimate: 50 kHz L1 rate for 45% eff. for VBF H→ττ
CERN-LHCC-2015-010
Same triggers also useful for HH→bbττLAr Calorimeter Upgrades

70

Upgrade of all readout electronics

To remove trigger constraints and improved radiation hardness
Possibly add new high-granularity precision timing detector in frontof endcap calorimeters
Primarily to reduce effect of pile-up on jets
Replacement of FCal evaluated, but found risky and unnecessary
58 front-end crates on 3 cryostats
1524 front-end boards
122 calibration boards boards

Possible newtiming detector

FCalLAr Electronics Upgrade

In Phase-I upgrade Level-1 trigger output path
Factor 10 increase in granularity – reused in Phase-II
Phase-II upgrade of readout electronics
Digital readout to back-end at 40 MHz
Alleviates current latency and trigger rate constraints
In addition original electronics only designed for 1000fb -1
LAr Phase II Electronics
Upgrade:• Re-use Phase I Trigger
Upgrade• New FE Boards (FEB2)• High Bandwidth Optical Links• BE: LAr Pre-PRocessor Boards(LPPR)

LAr Phase I Upgrade:••••

New Layer Summing Boards
New Baseplanes
FE: Trigger Digitizer Board (LTDB)
BE: Digital Processing System (LDPB)

71

High-Granularity Timing Detector

72

Evaluating option of adding thin, high-granularity timing
detector in front of end-cap calorimeter (2.5<|η|<4.2)
Multiple layers of silicon and optional tungsten absorber
Pad size: 1x1mm2 – 3x3 mm2
Timing precision: 30-50 ps
Minimum bias
High-granularity
Precise timing use to reject pile-up jets timing detector scintillators
Possibility for use in trigger
also being studied
Pile-up jet rejection power:

Efficiency strongly dependent
on timing resolution

Efficiency for hard-scatter jets

New Small Wheel

73

Will replace inner wheel of muon end-cap in Phase-I
Increased hit rate capability
Rejection of fake L1 muon triggers

MicroMegas – precision tracker
Spatial resolution <100μm
Good track separation

Small strip TGC – trigger detector
Bunch ID with good timing resolution
Track vector with <1mrad resolution

sTGC
MM
sTGC

Chamber production expected
to start very soonMuon Barrel Upgrade
To survive HL-LHC, gains on existing
RPCs will need to be lowered
Reduces muon trigger efficiency
Also existing acceptance only 78%

Will add new inner RPC station
Allows for 3 out of 4 layer coincidenceor even inner and outer RPC only
Increases efficiency to 92-96%

RPC chosen over MicroMegas
Also add RPCs at 1<|η|<1.3 in Phase-I
Acceptance without BI upgrade

Acceptance with BI upgrade74

Upgrade of TDAQ Architecture
Deciding between two-level hardware trigger with hardware
tracking at Level-1 and a high bandwidth single-level trigger

Low latency (25 μs) two-level system also under consideration
Trades latency for higher trigger rate and thus increased
trigger acceptance in certain channels – max rate TBD

75

TDAQ Upgrades

76

Level-0 trigger use Phase-I upgrades
Advanced algos with finer-granularity calo data:
Incl. longitudinal segmentation for e/γ/τ
0.1x0.1 towers for jets/ET,missUse NSW hits to confirm endcap muons

MDT information added to muon trigger
Sharpens turn-on curve and thus rejection power
Also allows looser RPC trigger selection, increasing acceptanceMultiple options for MDT track finding under consideration

Level-1 mainly adds tracking
Also plan to have full granularity
calorimeter data available

Track-trigger builds on FTK design
Pattern recognition with custom-made
Associate-Memory chips
Track fitting in FPGAs

FTK currently under installation
Expected to be commissioned in 2017

Triggering on HH→bbbb
HH→bbbb channel also difficult to trigger on at L1
Very large rate of multi-jets and pile-up jets
Plan to also use track trigger
to suppress pile-up jets
in 4-jet trigger
Still likely to only beefficient at 70-75 GeVATLAS estimate this will
reduce sensitivity by ~30%
compared to current 30 GeV
Better trigger strategy
is under investigation

77

ATL-PHYSPUB-2016-024