Production Readiness Review at PNPI Chamber assembling: Main production and quality control steps 30 January 2004 – G.Alkhazov 1.Input components control and preparation for assembling 2.Gluing the bars, control of the results of gluing 3.Wire winding, pitch control 4.Wire gluing, pitch control 5.Wire soldering, tension control 6.Soldering the HV capacitors, resistors, connectors 7.Assembling with O-rings, HV tests with air and working gas 8.Gluing the assembled chamber 9.Gas leakage test 10.Final HV test (current and noise) 11.γ-Ray test (checking gas gain uniformity)

Input components control and preparation 1.Panel thickness and flatness control is done by the production firm. Provisional thickness control at PNPI: d = 9.0+/-0.2 mm 2.Processing the anode panel edges for precise comb fixation. 2 man* hours per chamber 3. Panel surfaces polishing with special abrasive sponges 4 man*hours per chamber Panels

Input components control and preparation Control of the bar thickness d=2.40 μm (+50, -150) μm This thickness should be provided after processing the bars (2.4±0.15 mm ) at CERN 2.Processing the “noses” on the anode bars at PNPI It is a big job – about 5000 bars in total. It would be better to do this work at the company 3.Polishing the side bars and cathode bars for better sticking to the suction cups. It is a time consuming work. Would it be possible to receive the bars with better surface quality? Bars

4. Washing bars with alcohol 5.Visual checking of the printed circuit boards on the bars All these operations take about 4 m*hours per chamber ( not including bar “noses”) Input components control and preparation Bars

Gluing the bars Precision gluing with a gluing machine First, the bars are put on the gluing machine frame and fixed with the suction cups. Then, the glue (Adekit 140A) is put on the bars, and the frame is turned over and pressed to the panel. The distance between the surface of the frame and the panel is determined by the spacers. Glue polymerization requires at least 6 hours 1 chamber needs gluing of 8 panel sides. With 4 gluing tables operating in two shifts one can prepare 4 anode panels per day needed to produce one chamber per day. It takes 8 m*hours in 2 shifts. Critical procedure in the production scheme

Check of the thickness of the glued bars The distance H from the surface of the bar to the surface of the panel is measured in 24 points along the panel perimeter with a micrometer. The values, Hmin, Hmax are presented in the following table. This measurement takes about 2 m*hours per chamber.

MCPanelGapResult UP Down Panel_IDPanel PositionHmean,[mm]Hmin,[mm]Hmax,[mm]delta_H,[mkm]Hmean,[mm]Hmin,[mm]Hmax,[mm]delta_H,[mkm]Date_Tested. 13Pos 1/ DEC Pos 1/ DEC Pos DEC Pos DEC Pos DEC Pos 1/ DEC Pos 1/ DEC Pos DEC Pos DEC Pos 1/ DEC Pos DEC Pos JAN Pos 1/ JAN Pos 1/ JAN Pos 1/ JAN Pos JAN Pos JAN Pos JAN Pos JAN Pos JAN Gap Measurement Results

All panelsLast panels

Wire winding Wire winding is performed with the winding machine. Proper fixation of the combs is crucial for obtaining small pitch jitter and for putting the wires in the right positions on the printed circuit boards. The combs are adjusted in the longitudinal and transverse directions For the moment this procedure takes about 2 m*hours/panel Before winding the wires (of 30 μm diam.), the anode panels are washed with alcohol, and the guard wires of 100 μm are soldered at the edges of the winding zone. Winding is performed with the speed of 5 turns per minute. It takes about 2 hours for winding one panel By now, 9 anode panels have been wound.

Wire gluing Wire winding has been done, the wire pitch measuring is performed (with a wire pitch measuring machine). At this stage the wire positions may be corrected manually. If the results are O.K., then the wires are glued to the anode bars (Adekit 145A). This operation is done manually: first, the glue is put on a mylar tape, then this tape with the glue is put on the anode bar with the wires. The hardening of the glue takes about 1 day. After hardening the glue, the tape can be easily removed The pitch is checked again.

Wire soldering Before soldering the wires, the wires (excepting the zone of soldering) are covered with a protective shielding. Soldering the wires is performed with a soldering machine. Including the time for preliminary soldering machine adjustment, it takes about 3 hours per panel (2 sides). The quality of soldering is checked by visual control and by measuring pad capacities. Wires on 2 panels for 1 chamber are soldered in 1 day.

Measuring of the wire pitch

Soldering of the anode wires

Wire pitch distribution Anode plane 22, side UP

Wire pitch distribution Anode plane 22, side DOWN

Wire pitch distribution Anode 22 UP

ANODE 22 Wire pitch distribution Anode 22, Down

Results of pitch measurements For the first 12 wound planes, 98.8% of the pitches are around 2.0 mm within +/- 50 μm; 1.2% of the pitches are within +/- 80 μm. In 2 planes from 12, all pitches are within +/- 50 μm. Pitch jitter may be further decreased. Pitch measurement is rather quick: about 15 min. per plane.

Wire tension measurements

Wire tension measurement is performed with the tension measuring machine. From the stability consideration, the wire tension should be >50 g. Elasticity limit: 130 g. Average wire tension is from 63 to 67 g. (for 99% of wires). For 90-95% of wires the tensions are within +/- 8% (5 g.) from the average value. For about 1% of the wires (at the comb ends) in the wound panels the wire tension is smaller than the average value down to 20%.This effect should be eliminated in future. It takes 6-8 hours to measure wire tensions in 4 planes (!). We have 6 pairs of combs, it is desirable to have more.

Preparation of the panels for assembling The wire ends (protruding outside of the soldering spots) are removed. A careful check is performed to be sure that no wire ends have been left. The wires are covered with a protective shielding. Then the HV capacitors, the resistors, the connecters, and the HV and ground wires are soldered. (This procedure takes about 3 hours per panel). Before the chamber assembling, the wires are cleaned with ionized nitrogen. For these operations we need 2 operators to produce 1 chamber per day.

Gas leakage tests

Chamber assembling and HV tests First, the chamber is assembled with O-rings. A HV test is performed, the chamber being filled with air. We had current of nA at U=2-2.4 kV. (The air humidity was 25%). If the HV test is O.K., the chamber is filled with the working gas (Ar/CO 2 /CF 4 ; 40/50/10%). After 1 day of operation of the chamber kept at HV, we had current of nA at U=2.9 kV (air hum. 25%). The HV test having been done, the O-rings are removed, and the chamber is glued (Araldite 2011).

Final gluing of the chamber

Final HV test (current and noise)

Current from one double gap vs HV with Gamma source HV nom = 2.7 kV

Scan with gamma source middle left right

Scan with gamma source Separate pads

Scan with gamma source Separate pads

Scan with gamma source

Some conclusions All assembling technology has been tested. The required production rate would be possible after some additional actions: ◊ Tuning of the wire winding and wire tension machines ◊ Fixing the final gluing procedure ◊ Multiplying some tooling : * 6 sets of comb fixtures ( in addition to 6 available) * 5 sets of vices for O- ring assembling ( one is available) * more HV supplier lines etc. This tooling can be provided continuously during Feb-March The full production rate of one chamber per day can be planned for the end of April.