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

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

3. 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

4. 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

5. 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!

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

7. Length and Tension Measured During Production

8. 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

9. 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.

10. 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…

11. Leak found in tube wall during dark current / leak checking

12. 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

13. 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…

14. 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

15. 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.

16. 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.

17. 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.