RPC Production at GT A Mass scale RPC Production VIII Workshop on Resistive Plate Chambers 10-12 Oct, Seul - South Korea Domenico della Volpe - INFN Naples

Outline The Production Chain The Quality Assurance The Production Planning Efficiences of Production Stages Summary VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Where we start In the late 90’ several INFN experiment decided to use RPC technology form their detector They were: ATLAS, CMS, ARGO, OPERA, LHCb, ALICE. Each of them had milestones and the risk of clashes was high In the meanwhile the Babar crisis, pointed out some the critical item in the RPC Production INFN management had two main worries: The Gap Quality The Production Rate VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

The Creation of CCRPC In 2001 the INFN put together a Committee for Control of RPC Production (CCRPC), involving expert from each experiment with the goal of test the maximum production rate at GT to set-up new QC & QA procedures. Between September and December 2001 a first test was accomplish proving that 15 gap/per day was achievable and a set of QA & QC was set-up. VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

The beginning In 2002 the need of detailed planning was clear. It was started a planning agreed by experiment and a supervisor for this coordination between them was hired In the last 3 year this activity had a deep impact on the GT in terms of performances and quality. Here I will report the actual status, the production procedures, and QC & QA introduced VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

The Production chain

The Production Chain Bakelite preparation Selection Cleaning Graphite coating PET Film Gluing Gap Assembly Gap Finishing Frame Sealing Gas Inlet PET Frame Leak Test Gap Oiling Experiment QA & Test Quality Controls VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Bakelite Preparation Selection (by eye) MEK Wasking (Washing machine) Plate masking (manual) Graphite coating (automatic) R measurement (QC) PET Film Gluing La figura e’ sbagliata questa e’ la resistivita’ delle lastre. VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Gas Gap Assembly The Gluing Machine 2 table (2 gas gap at cycle) 18 slot “Pizzeria” 12 spacer per row 5 minute for spacer positioning 10 for frame and corner-pieces positioning and gluing VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Gas Gap Finishing - Hot Melt Frame sealing with an hot melt. The sealing is a crucial operation: important for gas tightness prevent HV leak. The smoothness of this operation has impact on HV leak Needs this special tool to handle big gap like OPERA or ARGO VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Gas Gap Finishing - Gas Inlet Positioned after the sealing In the past years drilled in. The drilling powder very dangerous: start local sparks Policarbonate corner pieces used where gas inlet are inserted later on. ATLAS VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Gas Gap Finishing - PET Frame Soon after the mass electric test started, was clear that a big amount of gas gap didn’t pass the experiment QA becase of current leak through lateral frame ATLAS proposed to reinforce the HV tightness adding a C-shape PET Frame This was tested to be very effective but the realization of such profile needs to be done automatically A tool for the realization of the PET frame and a press cut to cut the hole for gas inlet was realised Soon after the mass electric started, was clear that a hige amount of gas gap didn’t pass the experiment QA becase of current leak through lateral frame ATLAS proposed to reinforce the HV tightness adding a C-shape PET Frame This was tested to be very effective but the realization of such profile needs to be done automatically A tool for the realization of the PET frame and a press cut to cut the hole for gas inlet was realised VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Gas Gap Oiling Fast leak test is performed by GT 5 mbar is applied Less that 0.2 mbar leak in 20 minutes Oiling facility temperature: 30 °C 8-12 hrs to thermalize. 3 hrs for oil filling 36-73 hrs of purified air. VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Oiling QC Quality Control for the oiling are made: Oil viscosity (every tank filling up) Oil Sample Chemical analysis for checking polimerization Sacrificial gas gap Gap visual inspection Surface analysis of sacrificial gap with FTIR using ATR VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Oiling QC - Visual Inspection For each oiling cycle a sacrificial volume is chosen and open for a visual inspection Also a sample of the gap is taken to undergo a surface analysis VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Oiling QC - Lineseed analysis Good Oiling Line seed oil peaks Bad Oiling No line seed oil peaks VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Experiment QA VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Experiment QA Each experiment has specific requirements and then its own Quality Assurance. Anyway even if with different criteria, basically the QA check can be grouped in two classes: Spacer gluing (Push Test) Gap Current VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Spacer Gluing Each experiment has a maximum number of unglued spacer that can tolerate depending on their mechanics or overpressure supposed to be present on gas gap on installation site. CMS needs gas gap that can stand an overpressure of 20 mbar without unglued spacer The over pressure is so high that unglued spacer can be seen by eyes. In order to check unglued button the Babar people set-up a test method (Push-Test) used also by Atlas and OPERA VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Push test The gap is positioned on the table An overpressure of 5 mbar is applied to the gas gap. A weight of 600 grams is applied on each button in a single row by mean of a bar. In case of unglued button the weight can press the gap reducing the volumes a causing an increase in measured overpressure. The procedures is then repeated row by row VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Push Test GOOD GAP BAD GAP In case a bad row is found, the bad buttons can be found by lifting each weight until a depression in the shape is found. VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Push Test OPERA can accept just gaps without unglued button, so decided to setup an automatic test pushing all their chamber VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Current test Almost every experiment does a gas gap current measurement. Here I will report about the one done by ATLAS, because is the one a know better. The test is performed in two phase: a test with pure Argon before gap oiling (to check construction characteristic such as ohmic resistance, bulk resistivity, etc.) a test with the final gas mixture after the gap oiling (to check gap performances using the V-A characteristic) VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Argon Test Bulk Ohmic dominates Bad Chamber (early ignition) Ignition point Linear slope (or slowly logarothmic) VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Argon test What for? .. but also to check.. find patological gap to reject .. but also to check.. Bulk resistance Plate resistance VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Final Gas mixture test After oiling another V-A scan but with ATLAS gas mixture is done. Gas Gap with less than 2A/m2 (@9kV, @20°C) Reject Suspend Accept (Volt) VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Production Planning VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

The Plans Every Year a plan of the daily GT production has been done in order to optimize the speed, material procurement and experiment Milestone. On 3 month basis the plan has been revisited and re-arranged To do this a continuos monitoring of the production chain and of the material procurement was done VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

The Plan VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

The Production Status Last Update 1/10/05 VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Overall GT Production Something like 10000 gaps produced in 42 months Even if with several stop due to material shortage a mean value of 12 gaps/day was achieved VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Monthly GT Production The production was supposed to halve by the end of 2004 and finish by the middle of 2005 Still on and is supposed to finish by the beginning of next year VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

The Production Rate VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

The Production Rate VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Production rejection factor A Preliminary and incomplete look at the ATLAS production data

What for? In 2003 both ATLAS and CMS needed to revise their cost to completion of gas gaps Two main cause Gap improvements (PET-frame, QA) Big number of gap rejected At that stage not to much coherent data were available, so a guess was done 5% bad assembly by GT 20% by collaboration QA This means that 125% must be produced in order to have the 100% of layout VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

GT rejection factor The 5% estimation was correct (1721) (740) (648) (1030) (241) (4380) The 5% estimation was correct VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Current test Rejection Factor VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Current test Rejection Factor Condtioned room Winter Effect VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Current test Rejection Factor VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Current test rejection factor A significant improvement over the time Improvement of stability test condition Chamber reconditioning VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Conclusion - I A deep re-organization of the production chain was needed to go from hand made to mass scale production Big effort to organize production plan, material procurement, manage the milestone conflict Substancial revisitation of QC and QA procedure Delays were mainly due to material procurement (Bakelite) Panpla attitude can represent a real threat for future RPC production VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

Conclusion - II A first look at production efficiency was given This is a critical issue for future experiment mass scale production An a posteriori analysis shows that our guess in term of production efficiency were conservative The INFN goals were achieved VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe