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