Towards A Scintillator SemiDigital Hadron Calorimeter: Progress at NIUNICADD

1

• Towards A Scintillator (Semi)-Digital Hadron
  Calorimeter Progress at NIU/NICADD
• Jerry Blazey
• Northern Illinois University

2
LC Activities at NIU/NICADD

• Scintillator (Semi-)Digital Hadron Calorimeter
  Progress at NIU/NICADD This Talk
• Test Beam Plans for Scintillator Hadron
  Calorimeter Tail-catcher Vishnu Zutshi This
  Session
• G4-based Simulation Status Plans Guilherme
  Lima Session 7 Friday 830
• Muon Simulation Development Status Arthur
  Maciel Muon/PID Session Wednesday 100

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• Generic Calorimeter Simulations
• First Design Prototype Results on Sensitivity
  and Threshold
• Optimization of Unit Cells
• Light Sensor Investigations

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A Generic Calorimeter Number of Cells vs. Pion
Energy
0.25mip threshold
of Cells
100
E
20
For a 0.25 MIP threshold, cells
monotonically increasing with energy for a wide
range of cell sizes.
5
Digital vs. Analog
Energy 10,50 GeV p
Hits 10,50 GeV p
Hits ECAL
E ECAL
Hits HCAL
E HCAL
Very similar correlations exist for hits or
energy Between the EMCAL and HCAL
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Single Particle Energy Resolution

• Minimize (Eo-S(aiLi))2
• ai calculated for 10 GeV applied to all E,
  conservative
• i2 for EMCAL HCAL, also conservative

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Single Particle Energy Resolution
Non-projective geometry
s/E
0.1
E
20
For lower energy particles digital approach has
superior resolution!
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Resolution as a Function ofMultiple Thresholds
or Bits
2
1
E
As in the previous slide, below 20 GeV digital
resolution superior to analog. For E10 GeV,
more bits superior.
So it works for single particles how about jets?
9
Toy Simulation Recipe for a Jet

• Determine resolution independent of algorithm
• For ZZ events PT order stable MC particles,
  ignore ns
• For charged hadrons assume perfect energy (from
  tracker)
• Smear the energy of other particles
• For neutral hadrons use resolutions for charge
  pions (just discussed).
• For photons use s 17/sqrt(E)
• Start with highest pT particle and cluster in 0.7
  cone
• Repeat for remaining particles
• Add individual energies to get jet energy

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ZZ Events Sanity Checks
Neutral hadron fraction
Stable MC particles
10
g fraction
25
Energy Fractions
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Jet E Resolution
0.04
s/E
0.01
rms used
Jet E(GeV)
So the idea holds water At all energies 3x3
single threshold resolution comparable to analog!
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Using full DHC E-flow Jet Erec/Egen
Calorimeter only
Eflow
s 0.25
s 0.16
60 better
(Vishnu Zutshi, ECFA-DESY Workshop,
4/1/2003 http//nicadd.niu.edu, presentation 0046)
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Full DHC Eflow Jet Erec/Egen
Eflow digital (2cm2 cells)
Analog rather than hits
s 0.17
s 0.16
Digital approach not yet optimized but
performance comparable to analog!
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Hardware PrototypesStack, Layer, Unit Cell
WLS to Clear Fiber
MPTM
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Cosmic Data with PMT Readout
ADC
ADC
11 p.e. peak 1MIP
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0.25 MIP threshold efficient, quiet
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Cell Response Uniformity Dispersion
Cell-to-cell 7 (dominated by fiber)
Uniformity 3
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Other Uniformity Measurements
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Absolute Response Measurements(Purple Cast,
Blue Extruded)
Since light ample, can optimize for ease of
construction
20
Surface Treatment/Wrapping
Paint easy, little light loss
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Miscellaneous Measurementssource, glues, fibers
0.8 mm square Bicron
Extruded scintillator
1mm round Kuraray
Fiber has greatest affect on yield.
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NICADD/Fermilab Extruder
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Thickness Tolerance 2-3Response Depends weakly
on Thickness 20/mm
Thickness not an issue
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Optimum Cell

• Hexagonal or Square
• 4 - 9 cm2
• Straight Groove
• High yield fiber
• Glued Fiber and Painted Surface
• Extruded (cut costs) _at_ 5mm
• But a bigger question is the light sensor
• PMTs costly, bulky
• we have been investigating APDs, MRS, Si-PM

My current guess
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Hamamatsu Avalanche Photo-Diodes
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Cosmic MIP with Avalanche Photo-Diode
Hamamatsu S8550
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Metallic ResistiveSemiconductor (CPTA)
Representative Spectrum
Center for Perspective Technologies and
Apparatus
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Cosmics with MRS
60
0
50
51
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Si-PMs (PULSAR/MEPHI) mounted on cell?
Representative Spectrum
Moscow Engineering Physics Institute
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Cosmic Data with Si-PM
Number of P.E.
Comparable to PMT
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Tabulated Specs/Studies
A. Bross et al., Fermilab FN-0733, 2003 B.
Dolgoshein, An Advanced Study of Silicon PM,
ICFA IB, 2002 V. Rykalin, NICADD
presentation, http//nicadd.niu.edu , 2002
Estimate 10/channel or 1/cm2 for
Extruded/SiPM
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Scintillator DHC Conclusions

• Simulations indicate approach competitive with
  analog calorimetry
• Prototypes indicate there is sufficient
  sensitivity (light x efficiency) uniformity.
• Now optimizing materials construction to
  minimize cost with required sensitivity
• SiPM and MRS look very promising
• All-in-all looks like a competitive option.
• Well be moving towards the next prototype