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![Page 1: Study of a Compensating Calorimeter for a e + e - Linear Collider at Very High Energy 30 Aprile 2007 Vito Di Benedetto.](https://reader035.fdocuments.net/reader035/viewer/2022062423/56649e145503460f94afe6d5/html5/thumbnails/1.jpg)
Study of a Compensating
Calorimeter
for a e+ e- Linear Collider
at Very High Energy
30 Aprile 2007
Vito Di Benedetto
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ILCA future project for a
e+ e- Linear Collider
electron-positron collider;
ILC's design consist of
two facing linear
accelerators, each 20
kilometers long;
c.m. energy 0.5 - 1 TeV;
ILC target luminosity:
500 fb-1 in 4 years.
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Fourth Concept Detector (“4th”)
Basic conceptual design: 4 subsystems• Vertex Detector 20-micron pixels• Time Projection Chamber
Drift Chamber as alternative to overcome
known limitations of the TPC technology• Double-readout calorimeters
Fibers hadronic calorimeter:
scintillation/Čerenkov Crystals EM calorimeter
• Muon dual-solenoid spectrometer
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Requirements for ILC Detectors
Physics goal of ILC Wide variety of processes
Energy range: Mz<ECM<1 TeV
Basic detectors requirements Efficient identification and precise 4-momentum measurement
of the particles Extremely good jet energy resolution to separate W and Z
Efficient jet-flavor identification capability
Excellent charged-particle momentum resolution
Hermetic coverage to veto 2-photon background
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Calorimetry at ILC
Most of the important physics processes to be studied in the ILC
experiment have multi-jets in the final state
Jet energy resolution is the key in the ILC physics
The world-wide consensus of the performance goal for the
jet energy resolution is:
)GeV(/%30/ EEE
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Problems in Hadron Calorimeters
The most important fluctuation is in the em shower
fraction, fem
LESSONS FROM 25 YEARS OF R&D
Energy resolution determined by fluctuations
To improve hadronic calorimeter performance
reduce/eliminate the (effects of) fluctuations that dominate the
performance
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Measurement of fem value event by event by comparing
two different signals from scintillation light and
Ĉerenkov light in the same device.
Solution: Dual Readout Calorimeter
Unit cell
Back end of
2-meter deep
module
Physical
channel
structure
Dual REAdout Module (DREAM)http://www.phys.ttu.edu/dream/
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From DREAM to the 4th Concept HCAL
Cu + scintillating fibers
+ Ĉerenkov fibers
~1.5° aperture angle
~ 10 int depth
Fully projective geometry
Azimuth coverage
down to 3.8°
Barrel: 13924 cells
Endcaps: 3164 cells
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Simulation/Reconstruction Steps
inside ILCRoot FrameworkMC Simulation Energy Deposits in Detector
Digitization Detector response combined
Pattern Recognition Recpoints
Track Finding Tracks
Track Fitting Track Parameters
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ILCRoot: summary of features
CERN architecture (based on Alice’s Aliroot)
Full support provided by Brun, Carminati, Ferrari, et al.
Uses ROOT as infrastructure– All ROOT tools are available (I/O, graphics, PROOF,
data structure, etc)– Extremely large community of users/developers
Six MDC have proven robustness, reliability and portability
Single framework, from generation to reconstruction through simulation. Don’t forget analysis!!!
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Calibration
Energy of HCAL calibrated in 2 steps:
Calibrate with single 40 GeV e-
EC and E
S
Calibrate with single 40 GeV
C
and S
Sh
eS
Ch
eC
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Reconstructed energy
Once HCAL calibrated, calorimeter energy:
SC
SCCCSSHCAL
EEE
11
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HCAL Resolution Plots
40 GeV e-
40 GeV π-
S
S
C
C
EHCAL
EHCAL
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Reconstructed vs Beam Energy
Total Energy
Pattern
Recognition
cc & & ss
Independent Independent
on Energyon Energy
Pions data
all HCAL energy
single recpart energy
Visible Visible
energy fully energy fully
measuredmeasured
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Resolution for hadrons
Low statistics
Pattern
Recognition
Pions data
all HCAL energy
single recpart energy
/ndf 1.351e-05/4
P0 0.3545± 0.01041
P1 0.001335±0.001704
Total Energy
/ndf 1.435e-05/4
P0 0.3803± 0.01072
P1 0.0002627±0.001756
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Particle Identification
e
e
40 GeV particles
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Jets Studies
e+ e- -> q q (uds)
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The Jet Finder Algorithm Look for the jet axis using a Durham algorithm
Charged tracks
Calorimeter cells
Calorimeter Clusters
Jet core
Open a cone increasingly bigger around the jet axis (< 60°)
Run a Durham j.f. on the cells of the calorimeter inside the cone
Jet outliers
Check leftover/isolated calo cluster/cells for match with a track from TPC+VXD
Add calorimetric or track momentum
Add low Pt tracks not reaching the calorimeter
Muons
Add tracks reconstructed in the MUD
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Total Energy PlotsNo jet finderEnergy calibration with
no material in front
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Energy Resolution
Total visible
Energy (no jet
finding)
Single jet (jet
finding included)
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Physics Studies
e+e- -> ZoHo -> cc
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Jet Finder Performance
Angular resolution < 2°
Energy resolution = 4 GeV
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Jet-Jet Mass Plot
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ConclusionsThe 4th Concept has chosen a Calorimeter with
Dual Readout
The technology has been tested at a test beam,
but never in a real experiment
Performance of Calorimeter is expected to be
extremely good:
σE/E = 38%/√E (single particles)
σE/E = 39%/√E (jets)An ECAL design with Dual Readout crystal
technology is under way
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Bottom view of single cell
Bottom cell size: ~4.8 × 4.8 cm2
Top cell size: ~ 8.8 × 8.8 cm2
Prospective view of clipped cell
Cell length: 150 cm
Number of fibers inside each cell: 1980equally subdivided between Scintillating and CerenkovFiber stepping ~2 mm
Hadronic Calorimeter CellsHadronic Calorimeter Cells
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Simulation (1)
Light production in the fibers simulated through 2 separate
steps:
1. Energy deposition (hits) in active materials calculated by
the tracking algorithm of the MC
2. Conversion of the energy into the number of S and C
photons by specific routins taking account several
factors: energy of the particle, angle between the particle
and the fiber, etc. Poisson uncertaintity introduced in the
number of photon produced
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Simulation (2)
Response function of the electronics not
yet simulated (digits)
Random noise generated to test the ability
of reconstruction algorithm to reject such
spurious “hits”
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Reconstruction
Clusterization ( pattern recognition)
cluster = collection of nearby “digits” Build Clusters from cells distant no more than two
towers away
Unfold overlapping clusters through a Minuit fit to cluster shape
Reconstructed energy E adding separately ES
and EC of all the cells belonging to the
reconstructed cluster
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e+e- -> ZoHo -> cc Pandora-Pythia (Ecm=350 GeV, MH=140 GeV) + Fluka
No MUD (use MC truth) Cut recoil mass 20 GeV around Zo mass
Maximize j.f. efficiency through yt cut (ff=97%)