Gas Monitoring Chamber Production Status 27 June 2006 Curtis Weaverdyck, Alan Wilson, Micheal Kiesel

Outline Design Production Preparation for gluing Further work... Process & methods Statistics & complications Number of tubes produced (~100 usable) Preparation for gluing Further work...

Design Mini chamber to fit within standard half-rack – 50cm x 90cm Triggered by pair of scintillator paddles 50cm x 50cm Read out through standalone DAQ monitor run conditions Temperature Pressure Operate as 2 six-layer chambers

Design Parameters 3x8 electronics Separate gas systems right/left, but common feed to 2 MultiLayers Enclosed, insulated chamber box with fans for temperature stability Use of a single cut up gas bar dictates rotational symmetry instead of mirror symmetry Stand alone trigger paddles with fold-over light guides

Production: Stringing wire in tube Vacuum clamp tube to jig, thread wire through tube and endplug, crimp wire, and swage endplug. Flip around and repeat. Pins in end stop keep endplug holes aligned Threading wire through endplug was the most difficult part!

Tensioning & Measuring Tube Tensioned by pulling wire by hand until stable around 355 grams then… Clamped, crimped, and swaged. Measured length of finished tube

Length and Tension Measured During Production

Leak checking endplugs Used 3 bar He, required leak < 5x10-6 std ml/min Clamped o-rings on tube ends with pressurized air No nitrogen flushing One endplug possibly leaky ~10-5 std ml/min

Dark Current Checked in four groups of 24 (could have done up to 40, but some hardware was leaky), and one group of 8. Using premixed 93/7% Ar/CO2 Gas static during test. Dark currents for each group: 40, 25, 30, 15, 60nA (not much flushing of last). Ran overnight without 800nA current-limit tripping, current stable.

Leak Rate Gas sealed during dark current test. Monitored pressure with mechanical gauge. Precision ~0.1 PSI; could see significant leaks in ~10 minutes. Found at least one of these grey gas-jumpers had a large leak Also found one tube with a hole in the tube wall…

Leak found in tube wall during dark current / leak checking

Leak Rate # of Tubes ΔT (hrs) ΔP (PSI) Leak (ml/min) EML4 equiv. (mbar/day) 24 16.4 5.1 2.79 3.21 21.0 2.1 0.90 1.03 22.33 1.8 0.72 0.83 21.33 2.25 0.95 1.09 8 6.5 1.1 0.50 0.58

Tube Production Accounting 118 Tubes cut and cleaned 10 turned out to have incorrect wall thickness (0.11” instead of 0.16”) 1 wire broke during tensioning 1 tube was cut too short 1 tube end wasn’t deburred 105 Fully wired and OK 1 showed an endcap leak 104 Passed endcap leak test 1 had leak in tube wall (found during dark current/leak test) 103 Ready to be glued 2 have questionable tension 1 is short by at least 0.7mm 100 from which to choose 96 for gluing How? Some have known kinks in wire, questionable tension, outliers in tension and length…

Preparations for Gluing Moved three combs in center to accommodate our short tubes. Aligned combs, but then.. Had some suction leaks, so had to readjust. Need to get more epoxy mixing nozzles Old mixing nozzles wrong diameter to plug into 3-way nozzle. Gluing test done June 27

Glue Operations Use pneumatic cartridge gun to feed a large mixing nozzle into 3 way splitter, directly to Atlas nozzles on Gantry Move gantry by hand while dispensing Takes 10 minutes to glue a layer.

Gas System Have 8 small gas bars (8x3 section each) Slanting only in one direction, so each multilayer will have one gas bars sandwiched in the middle. Still need to be capped off Have enough steel tubelets of #1 and #3 type, but short on #2 bending the required direction. Should be able to fill in with “good brass,” but still need to check stock. Gas bar is type 2, without retaining groove for snap in black plastic pieces. Will use the black plastic o-ring retainers, but keep them in place with an aluminum bar.

Spacer Frame The Multilayers will nest in these frame pieces. The two MLs can be separated if necessary for work on the gas bars which are tucked between the two layers. Two small muffin fans will also be mounted between the MultiLayers to circulate air within the box and maintain uniform temperature.