TRD Collaboration meeting GSIClemens Adler First TRD Production Chambers Production Tests Results Documentation

TRD Collaboration meeting GSIClemens Adler Production of first Chambers Nov/Dec: Vist from Oleg and Sasha (Dubna): Parallel production of 2 chambers at Heidelberg Test of chambers: Christmas January 2004 New(s) (Challenges): -Glueing of Padplane-panel- assembly (100 cables have to be fed trough holes) -Wacosit Profile extruded in final shape (easier to use than standard G10 parts) -Winding machine after modifications

TRD Collaboration meeting GSIClemens Adler Padplane glueing Feeding cables trough Backpanel cutouts worked well Glueing of Padplane to Honeycomb works, but can still be improved

TRD Collaboration meeting GSIClemens Adler Wacosit profiles Wacosit is behaving good, minor quality improvements are discussed with Manufacturer

TRD Collaboration meeting GSIClemens Adler Wiring Oleg glueing Anode wires

TRD Collaboration meeting GSIClemens Adler What we learned: All current materials behave well. Tooling needed: –Positioning of wire ledges, –Distance ledges –Crane for lifting of winding frame (installed in January) –New winding frames (arrived)

TRD Collaboration meeting GSIClemens Adler Tests Dark current: (Was a Problem with Prototype chambers) At first dark current started at ~ V. After some conditioning (over night at <50 nA) Dark Currents <1 nA Leak Rate Xe-cost driven Gain uniformity Electronics driven

TRD Collaboration meeting GSIClemens Adler Preparation for tests Grounding of Padplane: –Adhesive copper tape: not reliable –Foldback clips, w. conductive foam: Complicated to use ->use of PCB with real connectors to ensure reliable grounding of Padpane while testing (in devel.) Gas filling: Issue: time Procedure: flush Chamber with l/h Ar/CO2 with open Gas-in-outlets ppm O2 level after 2-3 h. Connect outlet etc. and flush at 20 l/h overnight ->few ppm level next morning

TRD Collaboration meeting GSIClemens Adler Gain Uniformity Chamber1 Left: copper tape grounding Below: foldback clips grounding Low areas where foldback clip was not connected to ground Gain uniformity <+-10%

TRD Collaboration meeting GSIClemens Adler Gain Uniformity Chamber 2 Looks „flat“ Source collimation is not sufficient for detailed study ->X-Ray test stand should give better results

TRD Collaboration meeting GSIClemens Adler Leak rate Determined by measureing O2 concentration (and assuming diffusion leaks) Upper limit: 1,5-3 mbar*l/h Test chamber performance: <0,5 mbar*l/h (last year chamber: <0,2 mbar*l/h, with greased gas inlets)

TRD Collaboration meeting GSIClemens Adler Leak rate cont. I Solution : –Check that gas exits chamber down to low flow rates (1l/h). But: 1 l/h leak diffusion dominated? ->O2 conc. method fails –Use sniffer to detect leaks –??? Problem: very large leaks (some l/h) will also show „reasonable“ leak rates (<3mbar*l/h) with O2 method.

TRD Collaboration meeting GSIClemens Adler Leak rate cont. II Leakage of two connected chambers: Sniffer could detect leaks at gas connections. ->grease should be used to improve leak rate

TRD Collaboration meeting GSIClemens Adler Test parameter suggestions Leak Rate: upper limit: 1 mbar*l/h Gain Uniformity: ±15% limit (electronics limited) Reasonable goal: <0,5 mbar*l/h. Higher leak rates can be detected with a sniffer Reasonable goal: <± 10% ? Currently limited by the source. (pressure dependant) Absolute Gain Common Set of expected anode current values at defined parameters (Anode-,Drift- voltage)

TRD Collaboration meeting GSIClemens Adler Documentation of common standards Chamber building HowTo needed –Information is mostly there. Format?Format? Document with all Dimensions and allowable tolerancesDocument Document with Test limits (somewhat more explicit than in this presentation)