Particle Flow and Imaging Calorimeters:
Event Reconstruction for
Next Generation Colliders
Frank Simon
MPI for Physics & Excellence Cluster ‘Universe’
Munich, Germany

KEK Seminar
May 2010

With the LHC, Particle Physics is heading into the unknown,(hopefully) to discover New Physics beyond the Standard Model...

With the LHC, Particle Physics is heading into the unknown,(hopefully) to discover New Physics beyond the Standard Model...

With the LHC, Particle Physics is heading into the unknown,(hopefully) to discover New Physics beyond the Standard Model...

... what do we need to fully understand what we might find?

Linear Colliders: Precision at the Terascale• LHC will show us a rough outline of New Physics, but:
Detailed understanding needs additional precision measurements
What is the nature of Dark Matter?

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)3Linear Colliders: Precision at the Terascale• LHC will show us a rough outline of New Physics, but:
Detailed understanding needs additional precision measurements
What is the nature of Dark Matter?
Is the Higgs really “The Mother of Mass”?

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)3Linear Colliders: Precision at the Terascale• LHC will show us a rough outline of New Physics, but:
Detailed understanding needs additional precision measurements
What is the nature of Dark Matter?
Is the Higgs really “The Mother of Mass”?

Can be answered with a futurehigh-energy e+e- collider!

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)3

Concepts for the Next Big Collider• The International Linear Collider ILC• 500 GeV center of mass, upgrade up to 1 TeV• Proven super-conducting RF

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)4

Concepts for the Next Big Collider• The International Linear Collider ILC• 500 GeV center of mass, upgrade up to 1 TeV• Proven super-conducting RF• The Compact Linear Collider CLIC
• 3 TeV center of mass
• 2-beam acceleration

326 klystrons
33 MW, 139 µs
drive beam accelerator
2.38 GeV, 1.0 GHz(in development)

326 klystrons
33 MW, 139 µs

circumferences
delay loop 73.0 m
CR1 146.1 m
CR2 438.3 m

drive beam accelerator
2.38 GeV, 1.0 GHz

1 km

1 km
delay loop

CR1

BC2
TA r=120 m

delay loop

CR2

CR2
CR1

245 m

e– main linac, 12 GHz, 100 MV/m, 21.02 km

BDS
2.75 kmdecelerator, 24 sectors of 876 m
BC2

BDS
2.75 kmIP

245 m

e+ main linac

TA radius = 120 m

48.3 km
CR combiner ring
TA turnaroundDR damping ring
PDR predamping ringBC bunch compressor
BDS beam delivery system
IP
interaction point
dump

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010(c)FT

booster linac, 6.14 GeV
BC1
e– injector,
2.86 GeV

e–

PDR
398 m

e–

DR
493 m

e+

DR
493 m

e+

PDR
398 m

e+ injector,
2.86 GeV

Frank Simon (frank.simon@universe-cluster.de)4

Concepts for the Next Big Collider• The International Linear Collider ILC• 500 GeV center of mass, upgrade up to 1 TeV• Proven super-conducting RF• The Compact Linear Collider CLIC
• 3 TeV center of mass
• 2-beam acceleration

326 klystrons
33 MW, 139 µs
drive beam accelerator
2.38 GeV, 1.0 GHz(in development)

drive beam accelerator
2.38 GeV, 1.0 GHz

1 km
delay loop

TA r=120 m

delay loop

CR2

CR2

CR1

BC2
245 m

e– main linac, 12 GHz, 100 MV/m, 21.02 km

BDS
2.75 kmdecelerator, 24 sectors of 876 m
BC2

BDS
2.75 kmIP

245 m

e+ main linac

TA radius = 120 m

48.3 km
CR combiner ring
TA turnaroundDR damping ring
PDR predamping ringBC bunch compressor
BDS beam delivery system
IP
interaction point
dump

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

(c)FT

1 km
CR1

The scale of
New Physics will
determine whichmachine to build!

326 klystrons
33 MW, 139 µs

circumferences
delay loop 73.0 m
CR1 146.1 m
CR2 438.3 mbooster linac, 6.14 GeV
BC1
e– injector,
2.86 GeV

e–

PDR
398 m

e–

DR
493 m

e+

DR
493 m

e+

PDR
398 m

e+ injector,
2.86 GeV

Frank Simon (frank.simon@universe-cluster.de)4Outline• Hadronic Final States: Requirements at a Future Lepton Collider• Particle Flow Algorithms• The Concept• Expected Performance• Imaging Calorimeters• Focus Topic: Analog Hadron Calorimeter• Hadronic Showers in Imaging Calorimeters• 3D Studies of Showers• Energy Reconstruction• SummaryParticle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)5

Hadronic Final States:
Requirements at Future Lepton Colliders

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)6

Mass Resolution in Hadronic Final States• The precise requirements depend on the physics!
• Very likely of big importance: di-jet mass resolution

Typical case:A narrow resonancedecaying into quark
pairs

Significance:

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

S
∝√
B

1

∝!
σ(M )

Frank Simon (frank.simon@universe-cluster.de)7

Minimum Requirement: Separate Gauge Bosons• Gauge bosons (W, Z) are important signatures:• Can show up in many final states of heavy particles• Potential strong interaction: Scenarios forelectroweak symmetry breaking

e+

W/!"

e–

W/!"

q1

j4

j1

j2

j3

q2
q3
q4

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)8Minimum Requirement: Separate Gauge Bosons• Gauge bosons (W, Z) are important signatures:• Can show up in many final states of heavy particles• Potential strong interaction: Scenarios forelectroweak symmetry breaking

e+

W/!"

e–

W/!"

q1

j4

j1

j2

j3

q2
q3
q4

From discovery signal
to sensitive tool: along way to go!

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

UA1

Frank Simon (frank.simon@universe-cluster.de)8Mass Resolution: Requirements for separation• Width of gauge bosons sets a natural scale for the required resolution
perfect

2%

3%

6%

LEP-like

W/Z separation = (mZ − mW )/σm

effective gaussian equivalentmass resolution

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)9Mass Resolution: Requirements for separation• Width of gauge bosons sets a natural scale for the required resolution
perfect

2%

3%

6%

LEP-like

W/Z separation = (mZ − mW )/σm

effective gaussian equivalentmass resolution➫ The goal: ~3.5% jet energy resolution - Better does not buy much, due to natural width
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)9Mass Resolution: Requirements for separation• Width of gauge bosons sets a natural scale for the required resolution
perfect

2%

3%

6%

LEP-like

About a factor of 2 better than ATLAS
W/Z separation = (mZ − mW )/σm
(state of the art!)
effective gaussian equivalentmass resolution➫ The goal: ~3.5% jet energy resolution - Better does not buy much, due to natural width
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)9Where is the Challenge?
• Typical jet composition• 60% charged hadrons• 30% photons (mainly from π0 ➝ γγ)• 10% neutral hadrons (mainly n, KL)• Classical jet reconstruction relies exclusively
on calorimetry: 70% of jet energy measured in
the hadron calorimeter

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)10Where is the Challenge?
• Typical jet composition• 60% charged hadrons• 30% photons (mainly from π0 ➝ γγ)• 10% neutral hadrons (mainly n, KL)• Classical jet reconstruction relies exclusively
on calorimetry: 70% of jet energy measured in
the hadron calorimeter
Hadron Calorimeter: Limited energy resolution
typically:!
σ(E)/E ∼ 60%/ E [GeV](often worse)

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)10Where is the Challenge?
• Typical jet composition• 60% charged hadrons• 30% photons (mainly from π0 ➝ γγ)• 10% neutral hadrons (mainly n, KL)• Classical jet reconstruction relies exclusively
on calorimetry: 70% of jet energy measured in
the hadron calorimeter
Hadron Calorimeter: Limited energy resolution
typically:!
σ(E)/E ∼ 60%/ E [GeV](often worse)➫ Reduce the importance of the HCAL
for jet reconstruction!
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)10Particle Flow Algorithms

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)11

Particle Flow: A simple Idea
• Improve jet energy reconstruction by measuring each particle in the jet withbest possible precision• Measure all charged particles in the tracker (remember, 60% charged hadrons!)‣ Significantly reduce the impact of hadron calorimeter performance: Only forneutral hadrons‣ Measure only 10% of the jet energy with the “weakest” detector: significant
improvement in resolution

n

!#
"+

PFA

EJET = EECAL + EHCAL
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

EJET = ETRACK + E! + En
Frank Simon (frank.simon@universe-cluster.de)12Energy Flow: A first Step
• The idea behind Particle Flow is not new:Energy Flow by ALEPH at LEP (NIM A360, 481 (1995))• Identify electrons, photons, muons - remove from calorimeter hits
‣ Left with charged and neutral hadrons in the calorimeter• Reconstruction of neutral hadrons by subtraction
25 GeV calorimeter energy
20 GeV pion track
5 GeV neutral hadron➫ Energy resolution still dominated by hadron calorimeter(electron, photon, muon ID helps to improve jet resolution,neutral hadron ID by subtraction does not help)

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)13

Particle Flow:Very Different Detectors• Pushing the idea further: Identify neutral and charged hadrons in thecalorimeter directly‣ Requires extremely high granularity in the calorimeters

ILD

CDF

from this...
to this!
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)14

Particle Flow: A Challenging Concept• Key issues of PFA:
• Avoid double counting of energy• Separate individual particles

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

if these hits are
clustered withthese, the energy ofthe neutral hadron is
lost: Jet energy
measurement ruined

Frank Simon (frank.simon@universe-cluster.de)15

Particle Flow: A Challenging Concept• Key issues of PFA:
• Avoid double counting of energy• Separate individual particles

if these hits are
clustered withthese, the energy ofthe neutral hadron is
lost: Jet energy
measurement ruined

The level of mistakes, “confusion”, determines the achievable jet energy
resolution, not the intrinsic resolution of the calorimeters!

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)15

Particle Flow: A Challenging Concept• Key issues of PFA:
• Avoid double counting of energy• Separate individual particles

if these hits are
clustered withthese, the energy ofthe neutral hadron is
lost: Jet energy
measurement ruined

The level of mistakes, “confusion”, determines the achievable jet energy
resolution, not the intrinsic resolution of the calorimeters!
PFA Requirements:

Software: very sophisticated algorithms

Hardware:high granularity!"

Isolated neutral hadron or
fragment from shower ?

!"Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)15

Particle Flow Algorithms: Technology• The most performant PFA at present: PandoraPFA (Mark Thomson, Cambridge)• highly complex software package

NIM A611 24, 2009
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)16

PFA Technology: One Example• Iterative reclustering: Pushing the PFA Concept further• In a high-density environment (e.g. high-energy jet), pure PFA hits limits: Showers
can not be clearly separated• Use consistency of track momentum and shower energy to guide the clustering:recluster if energies are inconsistent

30 GeV

10 GeV

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)17

PFA Technology: One Example• Iterative reclustering: Pushing the PFA Concept further• In a high-density environment (e.g. high-energy jet), pure PFA hits limits: Showers
can not be clearly separated• Use consistency of track momentum and shower energy to guide the clustering:recluster if energies are inconsistent

18 GeV
30 GeV

10 GeV

12 GeV
10 GeV➫ much more powerful than subtraction or one-stage clustering
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)17

Particle Flow Performance• Detailed studies with PandoraPFA have been performed for the ILD detector
concept
Resolution is given as RMS90, the RMS of the
90% most central events:
PFA is inherently non-gaussian (driven by
confusion): narrow core, wide tails
In terms of analyzing power: RMS90 ~ 0.9 σGauss

For 45 GeV: Factor 3 better than LEP best (ALEPH)!

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)18

Particle Flow Performance• Detailed studies with PandoraPFA have been performed for the ILD detector
concept
Resolution is given as RMS90, the RMS of the
90% most central events:
PFA is inherently non-gaussian (driven by
confusion): narrow core, wide tails
In terms of analyzing power: RMS90 ~ 0.9 σGauss

For 45 GeV: Factor 3 better than LEP best (ALEPH)!
➫ PFA delivers unprecedented jet energy resolution:
Requirements for a Linear Collider are met!
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)18

Imaging Calorimeters
Detectors for Particle Flow

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)19Imaging Calorimeters• Particle Flow needs extreme granularity:• Electromagnetic Calorimeter• Small Moliere radius for shower separation: Tungsten absorber• Imaging capabilities: Read each layer separately, pads on each layer < Moliere
radius: ~ 5 x 5 mm2• Hadronic Calorimeter• Steel or Tungsten absorber (Tungsten to limit leakage for high energy jets)• Imaging capabilities: Read each layer separately (sampling ~ 1 X0 to retain
resolution for em subshowers), small cells: 3 x 3 cm2‣ Explosion of the channel count!
• ILD: ~100 M channels in ECAL, ~10 M channels in the HCAL
• Compare to LHC: CMS ECAL: 76 k channels, ATLAS HCAL: ~10 k channels

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)20

Imaging Calorimeters• Particle Flow needs extreme granularity:• Electromagnetic Calorimeter• Small Moliere radius for shower separation: Tungsten absorber• Imaging capabilities: Read each layer separately, pads on each layer < Moliere
radius: ~ 5 x 5 mm2• Hadronic Calorimeter• Steel or Tungsten absorber (Tungsten to limit leakage for high energy jets)• Imaging capabilities: Read each layer separately (sampling ~ 1 X0 to retain
resolution for em subshowers), small cells: 3 x 3 cm2‣ Explosion of the channel count!
• ILD: ~100 M channels in ECAL, ~10 M channels in the HCAL
• Compare to LHC: CMS ECAL: 76 k channels, ATLAS HCAL: ~10 k channels
About a factor of 1000 more channels: A totally different calorimeter technology!
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)20

ILD: Concept of a PFA Detector for the ILC• Typical collider detector:• Vertex detector• Large-volume tracking:
TPC• Calorimetry (em & had)
• Silicon-Tungsten ECAL
• Scintillator-Iron HCAL
• Muon tracking

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)21

CALICE: Proving the PFA Calorimetry Concept• Global Collaboration: ~330 Scientists from 57 Institutionsin 17 countries on 4 continents• The goal: Study different technologies for PFA calorimetry

physics
prototype
tested in beam

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)22

Imaging HCAL: Technological Basis• How do you increase the granularity (e.g. the number of channels) of ascintillator sampling calorimeter by 3 orders of magnitude?

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)23

Imaging HCAL: Technological Basis• How do you increase the granularity (e.g. the number of channels) of ascintillator sampling calorimeter by 3 orders of magnitude?
➫ Need tiny photon sensors that can be embedded in the detector!
Requirements: Insensitivity to magnetic fields, low operating voltage, low cost

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)23

Imaging HCAL: Technological Basis• How do you increase the granularity (e.g. the number of channels) of ascintillator sampling calorimeter by 3 orders of magnitude?
➫ Need tiny photon sensors that can be embedded in the detector!
Requirements: Insensitivity to magnetic fields, low operating voltage, low cost
The technology: Geiger-mode APDs / Silicon Photomultipliers (SiPMs):
Gain ~ 106
counting of single
photons is possible

Nx

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)23

Imaging HCAL: Technological Basis• How do you increase the granularity (e.g. the number of channels) of ascintillator sampling calorimeter by 3 orders of magnitude?
➫ Need tiny photon sensors that can be embedded in the detector!
Requirements: Insensitivity to magnetic fields, low operating voltage, low cost
The technology: Geiger-mode APDs / Silicon Photomultipliers (SiPMs):
Gain ~ 106
counting of single
photons is possible

Nx

scintillator read out with a SiPM

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)23

Analog HCAL: Active Elements• The unit: scintillator tile with SiPM

3 cm

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)24

Analog HCAL: Active Elements• The unit: scintillator tile with SiPM

• SiPM: 1156 pixels, manufactured by
MePhI/PULSAR
1 mm

3 cm

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Maximum efficiency in green spectral range:
Wavelength shifting fiber to collect and shift
blue scintillation lightFrank Simon (frank.simon@universe-cluster.de)24

Analog HCAL: Active Elements• The unit: scintillator tile with SiPM

• SiPM: 1156 pixels, manufactured by
MePhI/PULSAR
1 mm

3 cm

Maximum efficiency in green spectral range:
Wavelength shifting fiber to collect and shift
blue scintillation light• Active layers: 90 x 90 cm2
212 scintillator tiles (100 in highgranular core)
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)24

CALICE: Putting it all together
ECAL

HCAL

TCMT

Drift Chambers

Cherenkov
Detector
Beam
Sc1

Sc3

Sc4

Sc2

Muon Trigger

Scintillators

Si-W ECAL
1x1 cm2 lateral segmentation
30 layers, ~ 0.9 λ, 30 X0~ 10 k channels

Analog HCAL
3x3 - 12x12 cm2 lateral segmentation
38 layers, ~ 5.3 λ~ 8 k channels

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Tail Catcher / Muon Tracker
5 x 100 cm2 Scintillator Strips
16 layers~ 300 channels

Frank Simon (frank.simon@universe-cluster.de)25Extensive Test Beam Campaign• Beam tests at• DESY 2006
• CERN 2006, 2007
• FNAL 2008, 2009

• Electrons, Muons,Hadrons in a wide
energy range:
1 GeV - 80 GeV

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)26

Hadronic Showers in Imaging Calorimeters
3D Studies of Showers

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)27

Detailed 3D Images of Particle Showers• Study hadronic showers in a realistic detector in great detail• Provide input for next-generation detectors• Validate shower simulations• Crucial to establish the reliability of PFA simulation studies• Further improve shower modeling in GEANT4
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)28

Detector Simulations: GEANT4• A detailed model of the CALICE test beam setup is implemented in GEANT4• Includes absorbers, cassette material, electronics, scintillator, beam line
instrumentation, ...

• Digitization: Inclusion of noise from data, modeling of light collection,
saturation behavior of SiPM, ...
Different “Physics Lists”:
Model used to describe
hadronic shower
depends on particle
energy, combination ofdifferent models toachieve best description

LHEP (note: different scale)
FTFP_BERT_TRVQGSP_BERTQGSP_FTFP_BERTFTF_BIC➫ Significant differences between models for certain
observables, data can provide answers!
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

E [GeV]Frank Simon (frank.simon@universe-cluster.de)

29

Shower Studies: Things to look for

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)30

Shower Studies: Things to look for➫ Shower start point: Study shower properties without fluctuations of initial interaction

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)30

Shower Studies: Things to look for➫ Shower start point: Study shower properties without fluctuations of initial interaction➫ Transverse shower profile: Crucial for shower separation in PFA

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)30

Shower Studies: Things to look for➫ Shower start point: Study shower properties without fluctuations of initial interaction➫ Transverse shower profile: Crucial for shower separation in PFA➫ Longitudinal shower profile: Depth of calorimeter, leakage at high energies,...

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)30

Shower Studies: Things to look for➫ Shower start point: Study shower properties without fluctuations of initial interaction➫ Transverse shower profile: Crucial for shower separation in PFA➫ Longitudinal shower profile: Depth of calorimeter, leakage at high energies,...
➫ Shower substructure: Detailed information about hadronic interactions

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)30

Shower Studies: Things to look for➫ Shower start point: Study shower properties without fluctuations of initial interaction➫ Transverse shower profile: Crucial for shower separation in PFA➫ Longitudinal shower profile: Depth of calorimeter, leakage at high energies,...
➫ Shower substructure: Detailed information about hadronic interactions➫ Energy and energy density: Improved resolution with software compensation
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)30

Shower Start & Shower Profiles• Identification of the shower start point:

resolution:
Perfect for detailed studies andMC comparisonsParticle Flow and Imaging Calorimeters
KEK Seminar, May 2010

mip

energy density• Full profile of showers with highcm2 × event

Increase of activity in the detector

CALICE preliminary
10 GeV π-

10-1
10-2
10-3
10-4
0
100
200
300
400
r [m
m]

2000

Frank Simon (frank.simon@universe-cluster.de)

3000
2500
z [mm]

31

Transverse Shower Profiles: Comparison to MC
CERN 2007, 15 GeV !-

1

Data

-1

LHEP
QGSP_BERT10QGSP_FTFP_BERT

10-2

-3

10

CERN 2007, 15 GeV !-CALICE preliminary
Energy density: MC/DATA

Energy density [MIPs/mm2/event]CALICE preliminary

Data
1.4

LHEP
QGSP_BERTQGSP_FTFP_BERT

1.2

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CERN 2007, 15 GeV ! Data
QGSC_QGSCQGSC_CHIPSQGSC_BERTQGSC_BIC

CALICE preliminary

1.0

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50

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450

Radial coordinate [mm]
CERN 2007, 15 GeV !-CALICE preliminary
Energy density: MC/DATA

Energy density: MC/DATA

Radial coordinate [mm]Data
FTFP_BERT

1.4

FTFP_BERT_TRV
FTF_BIC

1.2

1.0

0.8
0.6
0.6
0

50

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Radial coordinate [mm]Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

0

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Radial coordinate [mm]Frank Simon (frank.simon@universe-cluster.de)32

Transverse Shower Profiles: Comparison to MC
CERN 2007, 15 GeV !-

1

Data

-1

LHEP
QGSP_BERT10QGSP_FTFP_BERT

10-2

-3

10

CERN 2007, 15 GeV !-CALICE preliminary
Energy density: MC/DATA

Energy density [MIPs/mm2/event]CALICE preliminary

Data
1.4

LHEP
QGSP_BERTQGSP_FTFP_BERT

1.2

1.0

0.8
10-4
0.6
-5

10 0

50

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400

450

0

1.4

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CERN 2007, 15 GeV ! Data
QGSC_QGSCQGSC_CHIPSQGSC_BERTQGSC_BIC

CALICE preliminary

1.0

0.8

50

100

150

200

250

300

350

400

450

Radial coordinate [mm]
CERN 2007, 15 GeV !-CALICE preliminary
Energy density: MC/DATA

Energy density: MC/DATA

Radial coordinate [mm]Data
FTFP_BERT

1.4

FTFP_BERT_TRV
FTF_BIC

1.2

1.0

0.8
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0.6
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Radial coordinate [mm]Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

0

50

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Radial coordinate [mm]Frank Simon (frank.simon@universe-cluster.de)32

Mean Shower Radius
Mean shower radius [mm]

100
95
90
85
80
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65
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55
50

!-, CERN 2007
Data
QGSC_QGSCQGSC_CHIPSQGSC_BERTQGSC_BIC

CALICE preliminary
100
95
90
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65

10

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Beam energy [GeV]! , CERN 2007
Data
FTFP_BERTFTFP_BERT_TRV
FTF_BIC

100
95
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85

60
55

-

CALICE preliminary
Mean shower radius [mm]• Mean radius, energy weighted
Mean shower radius [mm]!-, CERN 2007
Data
LHEP
QGSP_BERTQGSP_FTFP_BERTCALICE preliminary

50

10

20

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80

Beam energy [GeV]

80
75
70
65
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55
50

10

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80

Beam energy [GeV]Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)33

Mean Shower Radius
Mean shower radius [mm]

100
95
90
85
80
75
70
65
60
55
50

10

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30

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! , CERN 2007
Data
FTFP_BERTFTFP_BERT_TRV
FTF_BIC

100
95
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60
55

-

CALICE preliminary
Mean shower radius [mm]!-, CERN 2007
Data
QGSC_QGSCQGSC_CHIPSQGSC_BERTQGSC_BIC

CALICE preliminary

65

Beam energy [GeV]

80

50

10

20

30

40

50

60

70

80

Beam energy [GeV]• Inclusive variables alone don’t tell thewhole story!

• QGSC_CHIPS was found to be

75
70

buggy, fixed in latest GEANT4 release

65
60‣ Compare detailed distributions, use a

55
50• Mean radius, energy weighted
Mean shower radius [mm]!-, CERN 2007
Data
LHEP
QGSP_BERTQGSP_FTFP_BERTCALICE preliminary

10

20

30

40

50

60

70

80

Beam energy [GeV]Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

large variety of observables
Frank Simon (frank.simon@universe-cluster.de)33

The Anatomy of a Hadronic Shower: Longitudinal Profile• Use identified shower start: Factorization of distribution of first interaction
and shower development

AL

1
0

500

1000

pr

el
im
in
ar

y

20

10

E

IC

E

pr

2

30

IC

el
im
in
ar

3

data
shower start systematic
LHEP
QGSP_BERTFTF_BICQGSP_FTFP_BERT
QGSC_CHIPSFTFP_BERT_TRV

AL

y

4

80 GeV "+ ! 28.3°

0

C

mip
energy density
cm2 × event

data
shower start systematic
LHEP
QGSP_BERTFTF_BICQGSP_FTFP_BERT
QGSC_CHIPSFTFP_BERT_TRV

5

0

×10-3

10 GeV "- ! 28.3°

C

mip
energy density
cm2 × event

×10-3

0

500

1000

z [mm]z [mm]• Variations from physics list to physics list, LHEP shows different behavior thanother lists• Discrepancy with data in particular at high energy near the shower maximum
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)34

The Anatomy of a Hadronic Shower: Longitudinal Profile• Use identified shower start: Factorization of distribution of first interaction
and shower development
30

500

1000

pr

E

IC
AL
0

C

y

el
im
in
ar

pr

E

IC
AL
0

y

data
shower start systematic
LHEP
QGSP_BERTFTF_BICQGSP_FTFP_BERT
QGSC_CHIPSFTFP_BERT_TRV

Coming up: Decomposition of simulated
showers into separate
20
components - electromagnetic, hadronic, nuclear fragments➫ Detailed information to further improve
the physics lists
101
080 GeV "+ ! 28.3°

el
im
in
ar

4

2

mip
energy density
cm2 × event

data
shower start systematic
LHEP
QGSP_BERTFTF_BICQGSP_FTFP_BERT
QGSC_CHIPSFTFP_BERT_TRV

5

3

×10-3

10 GeV "- ! 28.3°

C

mip
energy density
cm2 × event

×10-3

0

500

1000

z [mm]z [mm]• Variations from physics list to physics list, LHEP shows different behavior thanother lists• Discrepancy with data in particular at high energy near the shower maximum
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)34

The Anatomy of a Hadronic Shower: Longitudinal Profile• Composition of showers for the ECAL (Silicon, Tungsten)• differences for HCAL expected: Sensitivity to neutrons due to Hydrogen in scintillator

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)35

The Anatomy of a Hadronic Shower: Longitudinal Profile• Composition of showers for the ECAL (Silicon, Tungsten)• differences for HCAL expected: Sensitivity to neutrons due to Hydrogen in scintillator

nuclear breakup

electromagnetic component

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

tail: hadronic & electromagnetic components
Frank Simon (frank.simon@universe-cluster.de)35

Digging Deeper: 3D Substructure - Particle Tracks
identified tracks• Imaging capability of detector
Beam
25 GeV π-

allows the identification ofindividual MIP-like tracks
within hadronic showers

ECAL upstream

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)36

Digging Deeper: 3D Substructure - Particle Tracks
identified tracks• Imaging capability of detector
allows the identification ofindividual MIP-like tracks
within hadronic showers

count

Beam
25 GeV π80
ECAL upstream

Tile I:43 j:46 layer 13
Landau+Gauss Fit:
MPV = 0.9938 +- 0.0175

70
60• Track identification provides a50

clean sample of minimum ionizing
particles: An alternative calibration
tool!

40
30
20
10
00

CALICE Preliminary
0.5

1

1.5

2

2.5

3

3.5

4

Amplitude [MIP]
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)36

CALICE preliminary

Mean Real Track Length [hcal layers]

Entries (normalized to no. Events)

Track Segments in Hadronic Showers: Length
π- data_rec_v0408
π- LHEP
π- QGS_BIC
π- QGSP_BERT_TRV
π- QGSP_BERT
π- FTF_BIC
π- FTFP_BERT

10-1

10-2

π- data_rec_v0408
π- LHEP
π- QGS_BIC
π- QGSP_BERT_TRV
π- QGSP_BERT
π- FTF_BIC
π- FTFP_BERT

12.5

12

11.5

11

20 GeV
5
1.6

10

15

10.5

20

25

30

35

µ component
in beam
1.02

CALICE preliminary
10

20

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80

10

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50

60

70

80

MC/Data

MC/Data

1.01
1.4
1.2
1

1
0.99
0.98
0.97

0.8

0.96

5

10

15

20

25

30

35

lengthReal Track Length () [HCal Layer]cos(θ)

Energy [GeV]• Track length and slope well described by all models:• Beam composition well modeled, satisfactory inclusion of detector noise• High energy cross sections well described
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)37

20 GeVCALICE preliminary

0.3

π- data_rec_v0408
π- LHEP
π- QGS_BIC
π- QGSP_BERT_TRV
π- QGSP_BERT
π- FTF_BIC
π- FTFP_BERT

0.25

0.2

0.15

Entries (normalized to Integral = 1)

Entries (normalized to Integral = 1)

Track Distributions: Angles & Multiplicities
π- data_rec_v0408
π- LHEP
π- QGS_BIC
π- QGSP_BERT_TRV
π- QGSP_BERT
π- FTF_BIC
π- FTFP_BERT

0.4
0.35
0.3
0.25
0.2
0.15

0.1

CALICE preliminary

0.1
0.05

0.05
1.2
0

10

20

30

40

50

60

10

20

30

40

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1

MC/Data

MC/Data

0
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0.9
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0
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1
0.8
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0.2
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1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

7

8

Track Angle [°]• Large discrepancy between different models

Track Multiplicity / event• Best agreement with QGSP_BERT• LHEP, QGS_BIC have too small angles and too small multiplicity: Insufficient
production of high-energy secondaries at large angles
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)38

Hadronic Showers in Imaging Calorimeters
Energy Reconstruction

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)39

Hadronic Showers: A Tough Business• The “secret” behind Particle Flow: Avoid the HCAL as much as possible
Why?

A calorimeter typically responds differently to the different components of the shower• Usually larger response for electromagnetic part
‣ Fluctuations from shower to shower limit the energy resolution‣ Energy dependence of average shower composition leads to non-linearities

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)40

Energy Reconstruction & Software Compensation• The CALICE HCAL is non-compensating: e/π ~ 1.3 (energy dependent)• High granularity provides detailed information for software compensation:• Electromagnetic energy deposits tend to be denser than hadronic ones
‣ Improvement studied on the cell (local) and on the cluster (global) level
Local method: apply weight to cells according to their energy, lower weight for cells withhigher energy content, weights are determined with a minimization technique

1000

hr

weighting

>t

600

400

200

0
0

e

r
E(>th

200

400

600

al)
E(tot
/
)
d
l
sho

800

= 0.3

1000

1200

1
=
l)
ta
ol

d)

/E

(to

800

es
h

es
h

ol

d)

/E

(to

800

20 GeV pions, energy density weighting

hr

ta

l)

=

1

20 GeV pions, no weighting

CALICE Preliminary

600

>t

CALICE Preliminary

(b)

E(

1000

Total HCAL Energy in Cells > 4.5 MIP/cell [MIP]

1200

(a)

E(

Total HCAL Energy in Cells > 4.5 MIP/cell [MIP]

1200

400

al) =
E(tot
/
)
d
l
sho

200

0
0

re
E(>th

200

400

Total HCAL Energy [MIP]

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

0.3

600

800

1000

1200

Total HCAL Energy [MIP]

Frank Simon (frank.simon@universe-cluster.de)41Software Compensation: Improved Energy Resolution• Compare two reconstruction methods:

entries/(event × 0.1 GeV)

• Simple reconstruction: Constant factor to convert calorimeter signal to energy

0.06

CALICE Preliminary
0.05

8 GeV
10 GeV
12 GeV
15 GeV
18 GeV

0.04

20 GeV
25 GeV
30 GeV

0.03

35 GeV40 GeV
60 GeV

0.02

80 GeV

0.01

0
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100

beam Energy [GeV]Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)42

Software Compensation: Improved Energy Resolution• Compare two reconstruction methods:• Simple reconstruction: Constant factor to convert calorimeter signal to energy• Local software compensation:
entries/(event
entries/(event ×× 0.1
0.1 GeV)
GeV)

Energy density dependent weighting, parametrized energy dependence
0.06
0.06

CALICE Preliminary
0.05
0.05

8
8 GeV
GeV
10 GeVGeV
101212 GeV
GeV
15
15 GeVGeV
18
18 GeVGeV
20 GeV
GeV
20

0.04
0.04

25
25 GeVGeV
30
30 GeV
GeV

0.03
0.03

35
35 GeVGeV
40 GeVGeV
40
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60 GeVGeV
80
80 GeV
GeV

0.02
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0.01
0.01

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00
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20

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40

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60

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80

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100

beam Energy [GeV]Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)42

Software Compensation: Local Method• Weights determined from data, parametrized energy dependence• No prior knowledge of beam energy necessary for application• Improved linearity of response, within ~3% from 8 to 80 GeV!E/E• without temperature correction, proton rejection: Better performance expected
0.25

in the near future!

Complete CALICE Setup(ECAL, HCAL, TCMT):CALICE Preliminary
0.2

Energy resolution
single weightenergy dependent parametrization

Resolution improved by ~ 18%

0.15

0.1

0.05

0
0

Fit: a/ E " b " c GeV/E
a = 61.3±0.1% b = 2.54± 0.10% c = 0.000± 0.041 [GeV]a = 49.2±0.4% b = 2.34± 0.12% c = 0.504± 0.042 [GeV]

10

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90

Resolution given by
Gaussian sigma / mean of a fit to
the distribution within 1.5σ of peakbeam Energy [GeV]Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)43Software Compensation: Local Method• Weights determined from data, parametrized energy dependence• No prior knowledge of beam energy necessary for application• Improved linearity of response, within ~3% from 8 to 80 GeV• without temperature correction, proton rejection: Better performance expected
E/E! weight/ !!single

0.25
1.05
1

in the near future!

Complete CALICE Setup(ECAL, HCAL, TCMT):CALICE
Preliminary
CALICE
Preliminary

0.2
0.95

Energy resolution
single weightenergy dependent parametrization

0.9
0.15
0.85

Resolution improved by ~ 18%

0.8
0.1
0.75
0.7
0.05
0.65
0.6
0 0
0

Ratio of energy resolutions
Fit: a/ E energy" b " cdependent
GeV/E
parametrization / single weights
a = 61.3±0.1% b = 2.54± 0.10% c = 0.000± 0.041 [GeV]a = 49.2±0.4% b = 2.34± 0.12% c = 0.504± 0.042 [GeV]

1010

20
20

30
30

40
40

50
50

60
60

70
70

80
80

90
90

Resolution given by
Gaussian sigma / mean of a fit to
the distribution within 1.5σ of peakbeam Energy
Energy [GeV]
beam
[GeV]
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)43Software Compensation: Global Method• Cluster finding in HCAL and TCMT to determine properties of the shower:
total energy, volume, length, width, energy in TCMT, energy in last 5 HCAL layers‣ Used as input for a neural net, training of the NN with simulations(quasi-continuous energy)∆E/E‣ No prior knowledge of the beam energy needed for application of method
0.25

CALICE Preliminary

HCAL+TCMT
NN trained with FTF_BIC

Energy resolution - FTF_BIC training

0.2

test beam data:
constant cluster weightneural network

0.15

Resolution improved by ~25%(~15% at 10 GeV, ~20% at 15 GeV)

0.1

0.05

Fit: a/ E ⊕ b ⊕ c GeV/E
a = 64.3±0.4% b = 0.00±0.73% c = 0.172±0.353 [GeV]a = 45.3±1.0% b = 1.97 ±0.39% c = 0.966±0.055 [GeV]

0
0

10

20

30

40

50

60

70

80

90

Resolution given by
Gaussian sigma / mean of a fit to
the distribution within 1.5σ of peakbeam Energy [GeV]Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)44Software Compensation: Global Method• Cluster finding in HCAL and TCMT to determine properties of the shower:
total energy, volume, length, width, energy in TCMT, energy in last 5 HCAL layers‣ Used as input for a neural net, training of the NN with simulations(quasi-continuous energy)‣ No prior knowledge of the beam energy needed for application of method
E/E
σweight/ ∆σsingle

1.05
0.25
1

CALICE
Preliminary
CALICE
Preliminary

HCAL+TCMT
NN trained with FTF_BIC

Energy resolution - FTF_BIC training

0.2
0.95

test beam data:
constant cluster weight

0.9

neural network

0.15
0.85

Resolution improved by ~25%(~15% at 10 GeV, ~20% at 15 GeV)

0.8
0.1
0.75
0.7
0.05
0.65

Ratio of energy resolutions - FTF_BIC training
beam
Fit:test
a/ E⊕ b ⊕datac GeV/E
a = 64.3±0.4% b = 0.00±0.73% c = 0.172±0.353 [GeV]
neural network / constant cluster weighta = 45.3±1.0% b = 1.97 ±0.39% c = 0.966±0.055 [GeV]

0.6
00
0

10
10

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70

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90

Resolution given by
Gaussian sigma / mean of a fit to
the distribution within 1.5σ of peakbeam Energy
beamEnergy [GeV][GeV]Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)44

reconstructed Energy [GeV]Software Compensation: Linearity of Response• Unweighted reconstruction

90
80
70
60

shows typical non-linear
behavior: Increased response athigh energies

CALICE Preliminary

Linearity of detector response - FTF_BIC training
test beam data
constant cluster weightneural network

50• Software compensation

40

recovers linearity within < 2%from 10 to 80 GeV30
20(Erec - Ebeam)/E

beam

10
10

20

30

40

50

60

70

80

90

10

20

30

40

50

60

70

80

90

0.1

0

Software compensation currently being
implemented in PandoraPFA: Further
improvement of performance expected-0.1

beam Energy [GeV]Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)45Outlook: Where Do We go from here?

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)46

Technological Diversity• Coming up: Alternative technologies for the HCAL:
Digital / Semi-Digital calorimeters using gas detectors as readout• x10 more channels than the analog HCAL: pad size ~ 1 cm2• 1 or 2 bits per channel• Insensitivity to neutrons (no hydrogen in active material!): Narrower showers,
might be an advantage for PFA
Different technologies:

Double GEM digital

ASIC
Front-End PCB

Communication
Link

Conductive Epoxy Glue
Pad Board
Signal pads
Mylar
Resistive paint

1.1mm glass

1.2mm gas gap
Fishing line
spacers
Resistive paint
Mylar

8.6
mm
HV

1.1mm glass

Aluminum foil

RPCs digital/semi-digitalParticle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Micromegas semi-digitalFrank Simon (frank.simon@universe-cluster.de)47

Higher Energy: Tungsten as Absorber• At a multi-TeV e+e- collider a very deep HCAL is required: Absorber withshort interaction length mandatory to fit detector into solenoid• Tungsten is an obvious choice• Tungsten is very different from Steel:• very different λ/X0 ratio: em subshowers very short• heavier nucleus: More neutrons in the shower➫ How well does a Tungsten HCAL work for PFA?
Need beam tests to answer!
The strategy: Use existing active layers, with amodified absorber structure, 10 mm W plates
in Al frames
30 layers in production for beam test at CERN
PS in November
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)48

2nd Generation: Engineering Prototypes• Realistic Calorimeter modules
under development:• Fully integrated electronics• Power pulsing to reduce heat load
• Realistic mechanical design

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)49

2nd Generation: Engineering Prototypes• Realistic Calorimeter modules
under development:• Fully integrated electronics• Power pulsing to reduce heat load
• Realistic mechanical design

Analog HCAL
compact layers:
3 mm thick tiles +electronics in a
cassette

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)49

2nd Generation: Engineering Prototypes• Realistic Calorimeter modules
under development:• Fully integrated electronics• Power pulsing to reduce heat load
• Realistic mechanical design

SiW ECAL:
Completemechanicalstructure

Analog HCAL
compact layers:
3 mm thick tiles +electronics in a
cassette

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)49

PFA at High Energy• PFA at high (multi-TeV) energy is challenging:Very narrow jets!
• Particle multiplicity does not change, boost increases density
125 GeV Z

250 GeV Z

500 GeV Z

1 TeV Z

These studies are just beginning:
PFA shows potential for significant improvements in mass reconstruction also athigh energies, potentially by reconstructing mono-jet mass instead of di-jet mass
➫ Much progress expected during the ongoing CLIC CDR phase!
Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)50

Conclusion• We need a high-energy linear collider to pin down New Physics• Particle Flow is a very promising technique to achieve unprecedented jet
energy resolution at such a machine: better than 3% over a wide energy range• Particle Flow Algorithm need extremely granular “imaging” calorimeters• Different technologies for such calorimeters are studied by the CALICE
collaboration• Imaging calorimetry works!
• Detailed studies of the structure of hadronic showers, important input for thefurther development of shower simulations• Advanced reconstruction algorithms for calibration and energy reconstruction• On the way to realistic detector prototypes

Particle Flow and Imaging Calorimeters
KEK Seminar, May 2010

Frank Simon (frank.simon@universe-cluster.de)51