Andy White
U.Texas at Arlington(for J.Yu, C.Han, J.Li, D.Jenkins, J.Smith, K.Parmer, A.Nozawa,
V.Kaushik)
10/18/04 IEEE/NSS
Digital Hadron Calorimetry for the Linear Collider Using Gas Electron
Multiplier Technology
Linear Collider Physics
A program of e+e- discovery and precision physics at 1TeV
Understanding the Electroweak sector
- Origin of mass – Higgs physics…couplings
- 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 -> hence the need for a new approach to hadronic calorimetry.
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 !
Simulation of W, Z reconstructed masses in hadronic mode.
(from CALICE studies, H.Videau,
shown at ALCPG/Cornell: M. Schumacher)
Importance of good jet energy resolution
60%/E
30%/E
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.
Digital calorimetry – counting cells
Digital Calorimeter Implementation
-There are a number of possible ways to implement digital hadron calorimetry:
- small scintillator tiles/SiPM (> 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
From CERN-open-2000-344, A. Sharma
GEM foil/operation
GEM field and multiplication
70m140m
Invented by Fabio Sauli/CERN
Double GEM schematic
From S.Bachmann et al. CERN-EP/2000-151
Create ionization
Multiplication
Signal induction
Design for DHCAL using Triple GEM
Ground to avoid cross-talk
Embeded onboard readout
Nine Cell GEM Prototype Readout
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Double-GEM prototype results: Gas mix
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Typical crosstalk signal (prototype)
Crosstalk studies
Sr90 (beta) source
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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.
(10 x 10) – 4 active area
Trace edge connector -> Fermilab 32 ch board
305mm x 305mm layer
GEM strip from 3M roll
305mm
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.
Development of GEM sensitive layer
9-layer readout pc-board
3 mm
1 mm
1 mm
Non-porous, double-sided
adhesive strips
GEM foils
Gas inlet/outlet (example)
Cathode layer
Absorber strong back
Fishing-line spacer schematic
Anode(pad) layer
(NOT TO SCALE)
3mm side walls and spacers installed
T2K large GEM foil design
(Close to COMPASS(CERN) foil design)
3M GEM foil – new layout
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.
Personnel
New collaborators on GEM/DHCAL:
- University of Washington, T. Zhou
- Tsinghua University, Beijing, China,
Prof. Jin Li,
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 stack…for 2006 beam tests at Fermilab