Andy White

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Digital Hadron Calorimetry for the Linear
Collider Using Gas Electron Multiplier Technology

Andy White U.Texas at Arlington (for J.Yu, C.Han,
J.Li, D.Jenkins, J.Smith, K.Parmer, A.Nozawa,
V.Kaushik) 11/10/04 ACFA
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Linear Collider Physics

• ? A program of ee- discovery and precision
  physics at 1TeV
• Understanding the Electroweak sector
• - Origin of mass Higgs
  physicscouplings
• - EW Symmetry breaking
  Supersymmetry?
• Precision studies of the massive top quark
• Search for New Physics W, Z, leptoquarks, .
• , extra dimensions
• ? Much of this physics program requires high
  precision measurements of jet energies and
  jet-jet invariant masses -gt hence the need for a
  new approach to hadronic calorimetry.

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Digital hadron calorimetry

• Need for high resolution energy measurements of
  jets
• example separation of W, Z in hadronic mode
• Three components of jet energy in calorimeter
• 1) electromagnetic measured well in e.m.
  calorimeter
• 2) charged hadrons track(s) cluster(s)
  in hadron and e.m. calorimeter
• 3) neutral hadrons cluster(s) in hadron
  and e.m. calorimeter
• - Use momentum measurement of charged hadrons in
  magnetic field, track them to energy clusters in
  hadron calorimeter, remove associated energy
  remainder is neutral energy (Energy flow
  algorithm)
• ? Must track charged hadrons in calorimeter !

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Importance of good jet energy resolution
60/?E
Simulation of W, Z reconstructed masses in
hadronic mode.
30/?E
(from CALICE studies, H.Videau, shown at
ALCPG/Cornell M. Schumacher)
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Digital hadron calorimetry (2)
A new approach - use small cells (1cm x
1cm) - cell is either ON or OFF. - high
granularity allows charged track following -
good correlation between energy and number of
cells hit. - requires development of
Particle Flow Algorithm to associate energy
clusters/tracks.
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Digital calorimetry counting cells
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Digital Calorimeter Implementation

• There are a number of possible ways to implement
  digital hadron calorimetry
• - small scintillator tiles/SiPM (gt 3cm x
  3cm)
• - resistive plate chambers (long term
  stability? rate?)
• - wire chamber/pads?
• OR
• a new approach Gas electron multiplier/1cm x
  1cm pads
• - easy to
  implement small cells
• - fast
• - robust

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GEM foil/operation
GEM field and multiplication
From CERN-open-2000-344, A. Sharma
Invented by Fabio Sauli/CERN
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Double GEM schematic
Create ionization
Multiplication
Signal induction
From S.Bachmann et al. CERN-EP/2000-151
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Design for DHCAL using Triple GEM
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Nine Cell GEM Prototype Readout
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ArCO27030
Double-GEM prototype results Gas mix
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Typical crosstalk signal (prototype)
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Crosstalk studies
Large Gap
Small Gap
Usual situation little xtalk
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Sr90 (beta) source
Scintillator-trig, dV400v, Sr-90, ArCo28515
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Next steps for prototyping

• Determined by availability of GEM foils of
  larger size.
• Likely short-term availability is for
  305mmx305mm foils from 3M Corporation.
• Plan is to build a cosmic (vertical) stack of
  5-6 layers using the 305mmx305mm foils.
• Use Fermilab 32-channel cards until ASIC
  available.
• Restrict readout to 10x10 channels/layer while
  using the Fermilab cards.

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305mm x 305mm layer
Trace edge connector -gt Fermilab 32 ch board
(10 x 10) 4 active area
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Development of large-scale GEM layer for final
test beam stack
1m
Test beam stack will be 1m3, with 40 active
layers each 8mm thick between steel absorber
plates.
305mm
GEM strip from 3M roll
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Development of GEM sensitive layer
Absorber strong back
Gas inlet/outlet (example)
Cathode layer
3 mm
Non-porous, double-sided adhesive strips
1 mm
1 mm
9-layer readout pc-board
Anode(pad) layer
Fishing-line spacer schematic
(NOT TO SCALE)
GEM foils
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3mm side walls and spacers installed
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T2K large GEM foil design
(Close to COMPASS(CERN) foil design)
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3M GEM foil new layout
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Readout Electronics

• Working with ANL/RPC Group on common front-end
  readout ASIC
• Selectable gain high for GEM, low for RPC.
• Circuit evaluation using SPICE at UTA
• Common PC board/anode pad layer with RPC
• Digital design complete, Analog design
  following BTeV chip. DHCAL specific final
  development in early 2005.

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Test Beam
(details are subject of separate presentation)
1m3 stack 40 layers, steel absorber, (shared with
RPC group) GEM active gaps,
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Personnel
New collaborators on GEM/DHCAL -
University of Washington, T. Zhou - Tsinghua
University, Beijing, China, Prof. Jin Li,
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Conclusions

• Development of a new type of digital calorimeter
• Prototype development sources/new gas mixtures.
• Mechanical tests for large area active layers
• Exploring using 305mmx 305mm foils in
  multi-layer cosmic stack as intermediate step to
  test beam.
• Ongoing discussions with 3M 4 other groups on
  foil development.
• Working towards a test beam stackfor 2006 beam
  tests at Fermilab