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The LP-TPC Fieldcage ProjectThe LP-TPC Fieldcage Project

Goal:

design, develop and build a field cage for a “Large Prototype” (LP)to be used for studies and development work towards a TPC at the ILC.

Members of the fieldcage group:

DESY, University Hamburg

as part of EUDET

Ties Behnke, DESY

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The fieldcageThe fieldcage

Size and boundary conditions:

defined through availablity of magnet (PCMAG)

Main parameters:

Length: 60 cm driftRadius: 80 cm (to allow external Si detectors, if wanted)

Lightweight, stable, flexible support more than one endplate with different readout technologies and ideas.

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The PrototypeThe Prototype

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LayoutLayout

Anode: Interface will be defined to allow easily interchangable endplates

Studies are needed to verify gas tightness etcStudies are needed to understand the HV distributionStudies are needed to understand the Gas supply at the anode

Cathode: At the moment no realistic design is planned. (no lightweightcathode at least in the first iteration)

Construction of the field cage will be done in close cooperation with industry

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Material StudiesMaterial Studies

Field cage wall:

composite structure, HV insulation through Kapton layersmechanical strength through GFK – NOMEX – GFK structure

Plans:

HV studies of the wall material this fall

investigate several “new” materials in place of Kapton

discussion with industry on ways how to wind the LP field cage are ongoing

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Optimization of LayoutOptimization of Layout

Work by Peter Schade, DESY

Configurations of different field strips:

Inside chamber cathodeanodeField strips

Mirror strips

Questions: mirror strips, yes or no? Arrangements of mirror strips

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Layout of Field StripsLayout of Field Strips

Field strips (front side)

Mirror strips (backside)

Divider for mirror stripsmounted inside the chamber

Divider for field strips, mounted inside the chamber

Not to scale

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Field OptimzationField Optimzation

No mirror strips

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ength

Large field distortions, particularly at cathode(>5%)

Inhomogeneous field for main drift regionof O(1.5%)

Anode Cathode

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With optimised mirror stripsWith optimised mirror strips

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5Mirror strips, at intermediate potential

Deviations in field volumesmall (< 0.5%)

Some residue deviationsat anode of O(<1%)(need optimization ofinterface endplate - drift volume)

Anode Cathode

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Plans:Plans:

Field cage design has started in earnest,

negotiations with industry to build the field cage have started

End 2006: freeze the final design, including all interface questions and material questions

mid 2007: have the fieldcage available

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Endplate PlansEndplate Plans

The “German” groups within LC-TPC have applied for a grant to design, build and operate an endplate for the LP

(members of this grant request are Aachen, Hamburg, Rostock, Siegen; external member is Cornell)

The idea:

design, construct and test an endplate for GEM readout

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The GEM Endplate The GEM Endplate

Some first ideas:

Light composite structure for the endplate

Use fairly “large” GEM modules

Main point is development of GEM modules, and ways to minimise material and (large) dead areas

Provide readout structure optimised for large number of points on track Pad geometries optimised for large field operations Readout electronics etc as defined by the EUDET Readout project

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Outlook and ScheduleOutlook and Schedule

Funding situation:

expect serious work on the endplate can only start in 2007

This will be “second generation” endplate compared to the Cornell one

The German groups are committed to this project, but we are very open to collaboration and sharing of tasks and responsibilities with other groups