Status of CERN M1R2 production LHCb Muon meeting sept.061Thomas Schneider -Beginning of 2006 two visits to Erbicol because of several reasons: -Material supply (PCB’s) -Material quality check -Fine adjustment of production procedure -July M1R2 chamber construction finished -Assembly started end of July … but leak problems -Investigation to understand the situation =>panels leak! -How repair the panels? -Conclusion M1R2 Status

Status of CERN M1R2 production LHCb Muon meeting sept.062Thomas Schneider Vistit to Erbicol: -The PCB production in ARTEL was delayed by 6 weeks. The tested circuits had to be shipped to ERBICOL as fast as possible. -This gave me the possibility to check the existing material already at place in ERBICOL. It was also useful to adopt the production procedure. “CERN panels are always a bit different” -Quite some problems appeared during this visit and the need for a second one became clear.

Status of CERN M1R2 production LHCb Muon meeting sept.063Thomas Schneider Material Quality Angular Pieces The design of these pieces was not coherent with the PCB design. They were 10mm outstanding => They has to be cut and re-glued For this kind of application the thickness of the angular pieces (5.6mm+/-0.05) should have been the same as the one for the Honey Comp (5.8mm) =>problem for planarity =>problem for leak tightness

Status of CERN M1R2 production LHCb Muon meeting sept.064Thomas Schneider Material quality Honey-Comp Due to the error of the angular pieces the HC was cut the wrong way (in the corners 10mm to short) A 3mm cell HC would have been quite appropriate: -Better mechanical stability on the border -Less problems to keep the drilled holes clean for the assembly

Status of CERN M1R2 production LHCb Muon meeting sept.065Thomas Schneider Production procedure: Due to the not precise angular pieces the corner areas had to be filled up with more viscous Glue. The out coming glue can be seen as the main source for the pollution on the Cathode surfaces. Different chemical product were used in ERBICOL to get the metallic surfaces “shiny” again. The result is a mixture of Glue and different cleaning products will still be in the grooves in-between the pads (in the gas volume) After a report of this visit to the people concerned we decided at CERN to protect the PCB surfaces with a thin plastic film.

Status of CERN M1R2 production LHCb Muon meeting sept.066Thomas Schneider M1R2 construction and first assembly: Beginning of the year I visited twice Erbicol. A report including concerns and question has been send to the people in charge. M1R2 construction started in April and was finished end of July. Due to delayed material (O-rings etc) and the re-assembly of M3R1 we were not able to assemble M1R2 in parallel. Only end of July we started with the first M1R2 assembly. The bad surprise was that the chambers were not leak tight! After quite some investigation we were able to locate the leaks. They are at the junction of the angular pieces and the PCB sheets in the gas volume (hole).

Status of CERN M1R2 production LHCb Muon meeting sept.067Thomas Schneider How to repair the panels? For the 60 outer panels of M1R2 the leak areas were still accessible. They can easily be repaired by sealing with one of our standard construction glues (Adekit 145A) For the inner panels the situation is much more complicated. The sidebars are glued on top of the leak area. There is no more “easy” access. 3 possible ways of repair have been tested: -Gluing along the side bar with Adekit 145 =>not leak tight - -Milling down the sidebar up to the level of the PCB. =>leak tight + quite destructive procedure - (dust, vibrations and problems to fix the panel) -Sealing the areas with a very liquid epoxy glue =>leak tight + new unknown component -

Status of CERN M1R2 production LHCb Muon meeting sept.068Thomas Schneider Conclusion  1.3 mm to the fracture Repair of M1R2: All Outer panels are repaired. After some discussion we decided to seal the inner panels with the more liquid glue. Already 4 chambers are assembled and tested for leak tightness. During the next 2 weeks the rest of the inner panels will be repaired the same way. For the moment we are working on the grounding scheme of the wire pads and the dressing of this chamber type.

Status of CERN M1R2 production LHCb Muon meeting sept.069Thomas Schneider Conclusion  1.3 mm to the fracture Repair of M1R2: All Outer panels are repaired. After some discussion we decided to seal the inner panels with the more liquid glue. Already 4 chambers are assembled and tested for leak tightness. During the next 2 weeks the rest of the inner panels will be repaired the same way. For the moment we are working on the grounding scheme of the wires and the dressing of this chamber type. We have 2 different problems ! One is the gas leak problem … solved! The other one is a lack of information and communication in the collaboration. People in charge of a sub-project, discovering a problem on this item have to communicate this to the other people/groups concerned !!!! Result:-additional 2 months delay for M1R2 -new component added