Mac Mestayer

DC12 Status: as of Feb., 2008

• Decide on endplate, feedthrough, wire material– guidance from small prototype chambers

• mainly electrical stand-off and noise issues

• Decide on frame designs– guidance from Reg. 2 prototype– constructability and accuracy of pre-bowed

endplates

• Large prototype tests– improve procedures, look for unknown problems

• Proceed with drawings, vendor qualification, …

Feb. 21, 2008 CLAS12 Drift Chambers: Status Report

Mac Mestayer

Prototype tests

• Wire-test chamber at ODU, Idaho St.– smaller diameter field wire ok; no extra noise– metal-tipped feedthroughs less noisy than all

plastic

• Full-scale Reg. 1 prototype– long wires ok; small electrostatic deflections– large temperature variation of wire tensions– many procedures to fine-tune– small modifications to electronics boards– no new problems

May. 29, 2008 CLAS12 Drift Chambers: Status Report

Mac Mestayer

Decide on endplate, feedthrough and wires

• Endplate materialaluminum (reg. 1): minimize dead area G10 (reg. 2): no eddy current if torus quenches steel-foam (reg. 3): very stiff structure

• Feedthrough materialglass-loaded Noryl with metal “trumpet” inserts

• Wire choices 30 m W, 80 m Cu-Be, 140 m Cu-Be for s, g, gless wire tension, thinner endplates

May 29, 2008 CLAS12 Drift Chambers: Status

Report

Mac Mestayer

Decide on frame designs pre-bowed endplate-in-a-frame

May. 29, 2008 CLAS12 Drift Chambers: Status Report

Mac Mestayer

Status: drawings, vendor qualifications

• drawings for Reg. 2 ~ 90% done• Reg. 2 endplate prototype – this summer• procurement strategy:

– feedthroughs: main vendor can help choose “inserts”

– wire: specifications known, ready for procurement– endplates/frames: reg. 1&2 – ready at end of

summer– assembly fixtures: ready at end of summer– Reg. 3: stay with standard “steel/foam” design?

(or go to a “reg2-type” design?)

May. 29, 2008 CLAS12 Drift Chambers: Status Report