calorimetry for fcc-hh

Calorimetry for FCC-hh

Martin Aleksa on behalf of the FCC-Calo Group

• Introduction: FCC-hh and FCC-hh Reference Detector• Calorimetry of the FCC-hh Reference Detector • Single Particle Performance• Conclusions & Outlook

Based on Material from the FCC CDR Summary Volumes (https://fcc-cdr.web.cern.ch/) and Studies by the FCC-hh Calorimetry Group (https://indico.cern.ch/category/8922/)

November 25, 2019 CHEF 2019 — M. Aleksa (CERN) 1

Kawachi Wisteria Garden, Kitakyushu, Fukuoka, Japan

https://fcc-cdr.web.cern.ch/

https://indico.cern.ch/category/8922/

Introduction – FCC and the FCC-hhReference Detector


Scope of FCC Study• International collaboration

(hosted at CERN) to study:– ~100 km tunnel infrastructure in

Geneva area, linked to CERN

– e+e- collider (FCC-ee), potential first step

– pp-collider (FCC-hh), long-term goal, defining infrastructure requirements

~16T 100TeV pp in 100km

– HE-LHC with FCC-hh technology

– Ions and lepton-hadron options with hadron colliders

• CDR for European Strategy Update 2019/20

CHEF 2019 — M. Aleksa (CERN)November 25, 2019 3

FCC Conceptual Design Report• Used as input for Update of European

Strategy in Particle Physics 2019– 4 CDR volumes submitted to EPJ in

December 2018

• Experiment & Physics Studies using FCCSW based on – 150 TB of full simulated data

– 100 TB of Delphes events

• https://fcc-cdr.web.cern.ch/


https://fcc-cdr.web.cern.ch/

Baseline Parameters for FCC-hh• Present working hypothesis:

– Peak luminosity:

• baseline: 5x1034

• ultimate: ≤ 30x1034

– Integrated luminosity:

• baseline ~250 fb-1 (per year)

• ultimate ~1000 fb-1 (per year)

• An operation scenario with…

– 10 years baseline, 2.5 ab-1

– 15 years ultimate, 15 ab-1

• … would result in a total of

O(20) ab-1 over 25 years of

operation.


Parameter FCC-hh HE-LHC HL-LHC

collision energy cms [TeV] 100 27 14

dipole field [T] 16 16 8.33

circumference [km] 97.75 26.7 26.7

beam current [A] 0.5 1.1 1.1

bunch intensity [1011] 1 1 2.2 2.2

bunch spacing [ns] 25 25 25 25

synchr. rad. power / ring [kW] 2400 101 7.3

SR power / length [W/m/ap.] 28.4 4.6 0.33

long. emit. damping time [h] 0.54 1.8 12.9

beta* [m] 1.1 0.3 0.45 0.15 (min.)

normalized emittance [mm] 2.2 2.5 2.5

peak luminosity [1034 cm-2s-1] 5 30 16 5 (lev.)

events/bunch crossing 170 1000 460 132

stored energy/beam [GJ] 8.4 1.4 0.7

Requirements for FCC-hh Detector• ID Tracking target: achieve σpT / pT = 10-20% @ 10 TeV

• Muons target: σpT / pT = 5% @ 10 TeV

• Keep calorimeter constant term as small as possible (and good sampling term)

– Constant term of <1% for the EM calorimeter and <2-3% for the HCAL

• High efficiency b-tagging, τ-tagging, particle ID!

• High granularity in tracker and calos

• Pseudorapidity (η) coverage:

– Precision muon measurement up to |η|<4

– Precision calorimetry up to |η|<6

• Achieve all that at a pile-up of 1000! Granularity & Timing!

• On top of that radiation hardness and stability!


Used in Delphesphysics simulations

VBF jets η-distr.

A Possible FCC-hh Detector – Reference Design for CDR


• Reference design for an FCC-

hh experiment developed to

demonstrate feasibility of an

experiment exploiting full

physics potential

• Input for radiation

simulations

• Input for Delphes physics

simulations

• Room for other ideas, other

concepts and different

technologies

Forward detectors up to η=6

Barrel HCAL: σE/E≈50%/√Ē⊕3%

Barrel ECAL: σE/E≈10%/√Ē⊕0.7%

Tracker: σpT/pT≈20% at 10TeV (1.5m radius)

Central Magnet:B=4T, 5m radius

23m

9m

Muon System: σpT/pT≈5% at 10TeV

1 MeV Neutron Equivalent Fluence for 30ab-1


Central tracker:• first IB layer (2.5 cm ): ~5-6 1017 cm-2

• external part: ~5 1015 cm-2 Calorimeter gap: from 1016 cm-2 to 1014 cm-2

Forward calorimeters:~5 1018 cm-2 for both the EM and the HAD-calo

Barrel calorimeter:EM-calo: 4 1015 cm-2

HAD-calo: 4 1014 cm-2

End-cap calorimeter:EM-calo: 2.5 1016 cm-2

HAD-calo: 1.5 1016 cm-2

Generally ~10-30 times worse than HL-LHC (similar for TID)Exception: Forward calorimeter goes to higher η bigger factor

FCC-hh Detector – Calorimetry


FCC-hh Calorimetry


• Good instrinsic energy resolution

• Radiation hardness• High stability• Linearity and uniformity• Easy to calibrate

• High granularity

Pile-up rejection

Particle flow

3D/4D/5D imaging

FCC-hh Calorimetry

FCC-hh Calorimetry


Reference DetectorInspired by ATLAS calorimetry: • Excellent conventional

calorimetry• In addition high granularity to

optimize for Particle Flow techniques, pile-up rejection, boosted objects….

• ECAL, Hadronic EndCap and Forward Calo (≥30X0):

LAr / Pb (Cu) • HCAL Barrel and Extended

Barrel (≥10λ):Scintillating tiles / Fe(+Pb) with SiPM

FCC-hh Electromagnetic Calorimeter (ECAL)


ZOOM

• Compared to ATLAS, FCC-hh Calo needs finer longitudinal and lateral granularity– Optimized for particle flow– 8 longitudinal compartments, fine lateral granularity – Granularity: Δη x Δφ ≈ 0.01 x 0.01; first layer Δη x Δφ ≈ 0.0025 x

0.02 ~2.5M channels

• Noble liquid (LAr) as active material– Radiation hardness, linearity, uniformity, stability

• Possible only with straight multilayer electrodes (no accordion)– Straight absorbers (Pb + stainless steel sheets in EM section)– Readout and HV on straight multilayer electrodes (PCBs, 7 layers,

1.2mm thick)

• EM Barrel: Absorbers 50∘ inclined with respect to radial direction – Sampling fraction changes with depth fsampl ≈ 1/7 to 1/4 – LAr gap 2 x 1.15mm to 2 x 3.09mm– Longitudinal segmentation essential to be able to correct!

• EM EndCap (EMEC): Straight Pb + steel absorbers and multilayer electrodes perpendicular to the beam axis

• Hadronic EndCap (HEC) and Forward Calorimeter: Straight Cu absorbers and multilayer electrodes perpendicular to the beam axis

EM Barrel

EM and HadronicEndCap

How to Achieve High Granularity?Realize read-out electrodes as multi-layer PCBs (1.2mm thick)• Signal traces (width wt) in dedicated signal

layer connected with vias to the signal pads• Traces shielded by ground-shields (width ws)

forming 25Ω – 50Ω transmission lines• capacitance between shields and signal

pads Cs will add to the detector capacitance Cd

• Ccell = Cs + Cd ≈ 100 – 1000pF• The higher the granularity the more shields

are necessary Ccell increases


Serial noise contribution proportional to capacitance Ccell

4 – 40MeV noise per read-out channel assuming ATLAS-like electronics

Hadronic showers: Energy sums over O(500-10000) cells

Performance of ECAL• Sampling fraction changes as function of the shower depth

– Longitudinal segmentation essential to be able to correct!– 8 longitudinal layers found to be optimal

• Required energy resolution achieved – Sampling term ≤ 10%/√Ē, only ≈300 MeV electronics noise despite

multilayer electrodes

• Challenge: Up to <µ> = 1000 interactions per bunch-crossing– Pile-up noise is dominating (up to 1.3GeV of pile-up noise)

– Out-of-time pile-up can be corrected for by clever reconstruction algorithms (already applied for ATLAS Phase I Upgrade) and by optimizing cluster size

– In-time pile-up can only be reduced by optimizing cluster size, using timing information or/and efficient pile-up suppression using the inner tracker


σpile-up noise = 3GeV (large cluster, <µ>=1000)σpile-up noise = 1.3GeV (small cluster, <µ>=1000)

Sampling fractionvs depth

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Performance of ECAL

• Position resolution important to perform combination between tracks measured by inner tracker and calorimeter clusters

• Fine φ segmentation in the first layer (Δη x Δφ ≈ 0.0025 x 0.02) and fine η-segmentation of other layers (Δη = 0.01) crucial for π0

rejection (H𝛾𝛾)– Excellent results obtained using

MVA with up to 15 variables– Deep Neural Network based

analysis shows similar results


500µm500µm

FCC-hh Hadronic Calorimeter Barrel (HCAL)

Barrel HCAL:• ATLAS type

– Scintillator tiles – steel

• Higher granularity than ATLAS– Δη x Δφ = 0.025 x 0.025– 10 instead of 3 longitudinal layers– Steel –> stainless Steel absorber

(calorimeter inside magnetic field), Pb spacers

• SiPM readout faster, less noise, less space

• Total of 0.3M channels• Calibration of scintillating tiles

(+SiPMs) using Cs source• Calibration of SiPMs using LEDs or

laser


e/h ratio very close to 1 achieved using steel absorbers and Pb spacers (high Z material)

ZOOM

First Tests with SiPMs in the Lab• First measurements in the lab using Sr90 source

and cosmics• SiPM (Hamamatsu S13360-1325CS)• Measured S/N ratio as a function of distance from

the wavelength shifting fibre


Components used for tests: • Scintillating tiles made of

polystyrene doped with 1.5% pTp and 0.04% POPOP and double cladding Y11

• Wavelength-shifting fibres from Kuraray

• SiPM: Multi-Pixel Photon Counter (MPPC) - Hamamatsu, type S12571-015C

e/h Ratio – Standalone π± Resolution• Steel absorbers partially substituted by lead

(all spacers)– Sci : Pb : Steel = 1 : 1.3 : 3.3

• By adding Pb decreasing non-compensation by suppression of EM response:– Pb: X0 = 0.6 cm, λ=17.6 cm– Fe: X0 = 1.8 cm, λ=16.8 cm

• Reduction of depth by 0.4 λ (at η = 0)


Combined Calorimeter ResolutionSingle π± resolution obtained from simulation with simple reconstruction “benchmark method”

• Correcting for energy lost in dead material between calorimeters by exploiting correlation between energy loss and geometric mean of neighboring layer energies


Results:• Sampling term of 44% (48%) achieved for B=0T (B=4T) respectively. • Constant term of ≈2% achieved• More sophisticated analysis (including local weighting) expected to further

improve this resolution• Ultimate energy resolution will be achieved using 4D imaging and particle flow

Combined Performance for Hadrons• FCC-hh calorimetry: High granularity of EM and HCal

• Ideal for particle flow techniques (but not yet implemented in SW)

• Which resolution can be achieved with calorimetry only, if using the full shower-imaging information?

• First results obtained using a convolutional neural network

– Training with 8M events (without any noise for the moment)

– Excellent results obtained Sampling term of 37%/√Ē (!!!)

– Very promising – further improvement expected using particle flow in combination with the inner tracker (being implemented into SW)


Noble Liquid Calorimetry for FCC-ee?


HCALECAL

Drift chamber

• FCC-ee experiment calorimetry requirements:– Excellent jet energy resolution (~30%/√Ē)– Photon measurement down to 300MeV low noise– Excellent particle ID

• High granularity calo for particle flow• Noble liquid calorimeter (as described before) and HCAL has

been integrated into FCC-ee Experiment in FCC SW• First implementation:

– Inner Tracker: DREAM-like drift chamber– ECAL: FCC-hh style LAr/Pb calorimeter– HCAL: FCC-hh style Tile calorimeter (Fe absorbers)– Solenoid coil outside the calorimetry

• Options which will be studied– Inner tracker: Si tracker– ECAL: W absorbers, LKr as active material, granularity optimization– HCAL: CLD-like HCAL– Solenoid coil in front of the ECAL, integrated into LAr cryostat (need thin

coil and low-material cryostat, see back-up)

• EP R&D work-package, also H2020 EoI has been submitted

Conclusions and Outlook• Noble liquid + scintillating Tile calorimetry has been successfully

used for LHC experiments (ATLAS Calorimeters) – Strengths: Stability, pointing resolution, particle ID, radiation hardness

• Similar calorimeter concept is proposed for the reference detector of FCC-hh– Simulations show that such a calorimeter would fulfil physics

requirements for FCC-hh– Excellent standalone performance for electrons and single hadrons– Physics objects performance will be shown in the next talk

• Noble liquid calorimetry is also an interesting option for an FCC-ee experiment!


Back-Up


Criteria for Physics Potential of Future Colliders – FCC-hh


M. Mangano, Sept. 2018

• Guaranteed Deliverables:– Study of Higgs and top quark properties, and exploration of EWSB phenomena, with unmatchable

precision and sensitivity• Sensitivity to the shape of the Higgs potential (Higgs self coupling)

– Ultimate precision standalone and in combination with FCC-ee and FCC-eh

• Exploration Potential:– Mass reach enhanced by factor ~ E / 14 TeV

• will be 5–7 at 100 TeV, depending on integrated luminosity

– Sensitivity to rare processes enhanced by orders of magnitude– Benefit from indirect precision probes at low and high Q2

• Provide YES/NO Answers:...to questions like…– Is the SM dynamics all there is at the TeV scale?– Is there a TeV-scale solution to the hierarchy problem?– Is DM a thermal WIMP?– Was the cosmological EW phase transition 1st order? – Could baryogenesis take place during the EW phase transition?

What Limits Granularity in ATLAS LAr?• In the ATLAS LAr calorimeter

electrodes have 3 layers that are glued together (~275µm thick)– 2 HV layers on the outside– 1 signal layer in the middle

• All cells have to be connected with fine signal traces (2-3mm) to the edges of the electrodes– Front layer read at inner radius– Middle and back layer read at

outer radius

• limits lateral and longitudinal granularity

• maximum 3 long. layers


Requirements for FCC-ee Calorimetry


FCC-ee


“IDEA”“CLIC-detector revisited - CLD”• Calorimetry requirements:– Excellent jet energy resolution (~30%/√Ē)– Particle ID

• High granularity calorimetry based on particle flow– Same technologies as for CLIC/ILC under study

• e.g. Si/W ECAL and Scintillator/Iron HCAL

– On top of that fibre-sampling dual-readout calorimetry could be a very interesting option for future leptonic colliders • Fine transverse granularity• Need longitudinal segmentation to separate e/𝛾

from π±! Idea with fibres of different length• Excellent hadronic resolution

(simulation ~35%/√Ē)

– Noble liquid based calorimetry• Calo only: Simulation with DNN calib. for

LAr ECAL + TileCal HCAL: ~37%/√Ē• Fine granularity particle flow reco with ID

Requirements for FCC-ee Calorimetry


Dimensions: Example CLD• Energy range of particles: – All particles ≤ 182.5 GeV

• 22X0 and 5-7𝜆 sufficient

– Measure particles down to 300 MeV (e.g. photons)• Little material in front of the calorimeter• Low noise (noise term dominant at small

energies, b≪ 300 MeV)!

• EM resolution as good as possible (≤ 15%/√Ē)– e.g. for CLFV τ decays τ → µ𝛾

• Jet resolution must be excellent (~ 30%/√Ē) to separate W and Z decays

• Position resolution of photons: σx = σy = (6 GeV/E⊕ 2) mm Particle ID: – e±/π± separation, – τ decays with collimated final states, separate

different decay modes with minimal overlap (e.g. π0 close to π±)

Could Noble Liquid Calorimetry Work? (1/2)• Dimensions:

– ECAL: 22X0: ~60 cm radial space for FCC-hh type LAr/Pb calorimeter (including 15cm cryostat thickness)• Could be further reduced to ~45cm by using W instead of Pb

– ECAL+HCAL: 5-7λ: ~1.2 m radial dimension for TileCal (FCC-hh style) – Calorimetry within Δr = 1.65m (W ECAL + TileCal) to Δr = 1.8m (Pb ECAL + TileCal).– Only slightly bigger than CLD (ΔrCLD = 1.4m)


• EM resolution: – Sampling term of ≈ 10%/√Ē quite easily achievable– Resolution at low energies dominated by noise term

• Noise term ≈ 300MeV achieved with FCC-hh calorimeter• Noise term of ≤ 100 MeV seems possible for low energy deposits

(optimized cluster size, see back-up)• In addition for large cell capacitances: Could probably gain factor 1.5

when going to slower shaping times τ ≥ 100 ns (FCC-hh τ = 45ns)

– To measure down to 300 MeV need to minimize material in front of the calorimeter ”thin” Al cryostat or carbon fibre cryostat (R&D program at CERN has been launched, see next slide)

R&D on Low Mass Composite Cryostats


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Could Noble Liquid Calorimetry Work? (2/2)• Jet resolution

– Requirement: (~ 30%/√Ē) to separate W and Z decays– Calo only: hadron resolution (π-) achieved in FCC-hh (LAr ECAL + TileCal HCAL):

• Benchmark reconstruction: ~48%/√Ē• Simulation with DNN calibration ~37%/√Ē• Already close to the required 30%/√Ē

– Particle flow will further reduce the jet resolution (not simulated yet)– Future jet energy reconstruction will probably use machine learning to

combine tracker information and full 3D imaging information

• Particle ID:– Fine granularity in η, φ, depth can be adjusted according to needs (PCB)– E.g. FCC-hh first calorimeter layer 5mm x 20mm cells (x 9cm depth)– Similar segmentation of read-out electrode would lead to cell sizes of 2.5mrad

x 2.5mrad for FCC-ee

• Position resolution:– For FCC-hh achieved ση ≈ 2x10-3/ √Ē– ≈ 4.4mm/√Ē ~1mm for 20GeV (2mm for 5GeV) sufficient

• Timing:– ATLAS LAr: Timing resolution of 150ps achieved for EM showers ≥30GeV, 65ps

for EM showers ≥100GeV– Possibility to further improve this resolution – studies needed and planned


Example: Optimize Noise for FCC-hh Calorimeter


Challenge: Good photon energy resolution down to 300MeV: – 30% resolution at 300MeV if noise level can be kept below 100MeV

– Cluster size optimization (only first layers have significant energy deposits) less cells per cluster less electronics noise

Courtesy A. Zaborowska

Only 3.5% of the energy in layers 5 to 8 (for 300 MeV photon)

calorimetry for fcc-hh

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