UPDATE ON GEM/DHCAL DEVELOPMENT AT UTA

Andy White

U.Texas at Arlington

(for J.Yu, J.Li, M.Sosebee, S.Habib, V.Kaushik)

9/15/03

Recent developments

Moving to multi-channel prototypes

GEM foil production

Electronics – prototypes

Module design concepts

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

Multichannel prototype

- Next step: a 3 x 3 array of 1 cm2 pads.

- Allows one central pad with neighbors for cross-talk tests.

- Use a single layer board for simplicity.

- Anode board built, prototype reworked.

- First results.

Nine Cell GEM Prototype Readout

Landau Distribution from Cs137 Source

Signal Amplitude (mV)

Readout electronics for DHCAL/GEM

- Single channel electronics for first tests

(high gain charge preamp + x10 voltage amp.)

- Useful for initial development, but not cost effective for larger scale, multi-channel prototypes.

GEM Prototype with preamp/voltage amp

Amptek charge pre-amplifier

Readout electronics for DHCAL/GEM

- Discussions with Fermilab/PPD (Ray Yarema)

- Short-term use of electronics developed for silicon readout. (T.Zimmerman)

- 32 channel boards. Now at UTA.

- Gain within factor of 3 of present single channel system.

- Investigating DHCAL/GEM specific design

- Coherence with DHCAL/RPC – VME/daughter?

Fermilab preamp

for multi-channel tests

GEM Foil Production

- Original production at CERN – but slow, low volume, manpower intensive and expensive.

- Interest in U.S. domestic foil production by LC tracking developers and GEM/DHCAL.

- 3M Corporation (Microinterconnect Systems Division), Austin, Texas has tried additive and subtractive approaches.

- Foil production on 16 inch wide, 500 feet long roll.

Our Motivation: Micro Pattern Gas Detectors (MPGD) in Particle & Astro-Particle PhysicsTPC readout for LC (GEM or MICROMEGAS)Tracking device at SLHC or VLHCLow-background applications (e.g. coherent neutrino scattering) & WIMP searches

Chicago-Purdue-3M

P.S. Barbeau J.I. Collar J. Miyamoto I.P.J. Shipsey

+ DHCAL/GEM developments

+ Medical imaging potential

+ ?

GEM Foil Production

• 3M Microinterconnect

Systems Division Reel-to-reel

process, rolls of 16”’x16” templates of detachable GEMs in any pattern. Optional processes possible.

• First batch of 1,980 GEMs recently

produced. Low cost per unit! (~2 USD/GEM not counting R&D)

• Two fabrication techniques (additive,

substractive) tested.

Singleroll of~1,000GEMS

Reel to reelflex circuitmanufacturein clean roomconditions

hep-ex/0304013

Mass Production is based on a 3M ProprietaryFlex Circuit Manufacturing Technique

Subtractive (etching) (similar to CERN made GEMs)

Additive Cu added to patterned photo resiston Kapton

Two fabrication techniques

Subtractive Additive

1. Subtractive: Clean hole structure, microcrystals, a small part of the batch have problems with adhesion of Cu on Kapton

2. Additive: Some holes not perfectly round create hole to hole gain variation, a small part of the batch have problems with adhesion of Cu on Kapton

hep-ex/0304013

Cumicrocrystal

Additivemethodneeds improvementto be useful

3M Process Quality

ChicagoPurdue3M GEM

SEMCourtesyFabioSauli

Subtractive 3M Mass Produced GEM

ChicagoPurdue3M GEM

SEMCourtesyFabioSauli

Hole Profile

GEM Performance

Typical 55Fe spectrum uncolllimated source. Ar + 5% CH4 Lower GEM electrode. E/E = 16% typical energy resolution as goodas 14% observed.

hep-ex/0304013

So far characterization focused on subtractive GEMs

3M GEM and CERN GEMHave comparable E/E = 16%

3M GEmE/E = 16%

CERN GEME/E = 18%

http://gdd.web.cern.ch/GDD/

Ar/DME 9:1

Ar/CO2 7:3

Gain measuredon lower GEM electrode

Gain measuredon PCB below GEM

Gains of 5,000 in Ar/CO2 7:3 & Ar/DME 9:1

Gain almost identical to CERN made GEMS in same gas

xx

CERN GEM *

(*) S. Bachmann et al.NIM A479 (2002) 294

Gas Gain

hep-ex/0304013

CERN

GEM Foil Production

- Latest production 2 x 2 pattern of 10x10 cm2 foils.

- Use for DHCAL small prototypes and module development

- 3M can make any pattern within the roll parameters (~$2K for artwork)

TESLA – HCAL Layout

Development of module concepts

DHCAL/GEM Module concepts

Use half-size modules w.r.t. TESLA design

DHCAL/GEM Module concepts

Bottom view

Side view

End view

DHCAL/GEM Module concepts

GEM layer slides into gap between absorber sheets

DHCAL-GEM Layer structure

- GEM layer -> 6mm

- Electronics layer ~3mm

- Absorber thickness 16mm x 40 layers

-> ~ 4 interaction lengths for HCAL

- 10x10 mm2 cell size -> ~1.5 x 107 channels for DHCAL-GEM

DHCAL/GEM active layer

- Basic layer structure is clear

- Practical issues:

- minimizing thickness, readout layer, ground plane(s) ??

- stretching foils, foil separators, wall thickness

- gas in/outlets, electrical services

DHCAL/GEM active layer

- Exploring using the absorber steel gap to provide active layer rigidity.

- Build jig to construct active layer with stretch foil layers, thin side walls.

- Test transfer/sliding of non-rigid active layer into steel gap.

- Start with available width foils from 3M

Design concept for sensitive layer

3mm ionization

layer

CONCLUSIONS

Further prototype development

Exploring electronics solutions with Fermilab/PPD

Availability of U.S. domestic GEM foils

Investigating active layer construction techniques