A Digital Hadron Calorimeter ?

1
A Digital Hadron Calorimeter ?

• Vishnu V. Zutshi
• NIU/NICADD

2
The proposal

• Development of New Hadronic Calorimetery
  Technology
• G. Blazey, D. Chakraborty, A. Dyshkant, M.
  Martin,
• V. Rykalin, V. Zutshi
• NIU/NICADD
• A. Brandt, K. De, A. White, J. Yu
• UTA

Arrive at a realistic cost estimate for one of
these devices
3
From analog to digital

• Eflow seems to be a promising option for
  improving jet resolutions significantly
• ALEPH and CDF have successfully used it
• Requires a high granularity calorimeter
• Digital hadron calorimeters high granularity at
  affordable price ?

4
General Considerations

• Granularity (energy and resolving power)
• MIP recognition
• Absorber density (optimize shower lateral size)
• Depth
• Matching to EM calorimeter
• Readout (2d preferred to strip type)
• Minimal intrusions

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Energy and position
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Too much of a good thing?
7
Analog and Digital
20 GeV pions in SD
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Single Particle Resolutions
9
On the software side of things

• Prototype simulations
• try out different cell shapes
• parameterized losses from test stand
• hoping to do this in GEANT4 framework
• Event generation and LC detector simulation
• Eflow algorithm development
• starting with the EM section

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The Algorithm (cal-seeded)

• Layer-by-layer clustering based on a search for
  local maxima
• Cluster definition based on nearest neighbour
• Track extrapolation through the calorimeter
  picking clusters in its path
• EM/HAD. Charged/neutral discrimination
• Understanding of errors involved with the
  tracking and calorimetric measurements

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Sanity Checks
clusters
hits
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Initial concept (scintillator-based)
Four concentric layers of towers (7 stacks of
6-12 cells to a tower) formed with hexagonal
cells. Start with 9cm2 cell.
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Initial concept (scintillator-based)

• Conversion to current
• VLPCs
• APDs
• MRSs
• PMTs
• Cost per channel v/s S/N

14
Test stand
Cell with WLS fiber irradiated by a radioactive
or LED WLS fiber connected to clear fiber which
is connected to a photodetector (PMTs, VLPCs
etc.) Output measured by a Pico ammeter
15
Test goals
Find minimum area/thickness of cell Find minimum
length of WLSF
Measure signal losses at the WLSF to clear fiber
transition
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MIP signal
With VLPC readout
9mm thickness,0.5mm fiber,2optical connectors
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Initial concept (gas-based)

• GEM approach
• Developed initially for MSGCs
• Can be used with printed circuit readout
• GEMs with gains above 104 and spark
  probabilities lt 10-10 have been developed
• Reasonably fast operation
• Relatively low HV

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Initial concept (gas-based)
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Issues/concerns (gas-based)

• Cost of GEM layers
• Lifetime/damage to layers
• Effects of highly ionizing particles
• Gas(es) ?
• Mechanical stability of GEM gaps/supports
• Cross-talk
• ..

20
Summary

• Single cell characterization studies have begun
• GEM based feasibility studies starting soon
• Event generation and simulation server ready
• Setting up for GEANT4 based prototype simulation
  studies
• Eflow algorithm development underway