1. 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

2. 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

3. 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

4. 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

5. 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

6. The Production chain

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

26. Final Gas mixture test
After oiling another V-A scan but with ATLAS gas mixture is done.
Gas Gap with less than
Reject
Suspend
Accept
(Volt)
VIII Workshop on RPC, Oct 2005, Seul - RPC Production at GT - D. della Volpe

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

28. 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

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

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

31. 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

32. 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

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

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

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

36. What for?
In 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

37. 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

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

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

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

41. 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

42. 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

43. 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