Production Readiness Review of Frascati MWPC Production Site December 4 th, 2003 – P. Campana

Scope and Goals of the PRR Verify / assess : Readiness of the chamber design and of the construction procedures Readiness of the tooling and of the production site Quality controls and assurance tests Material procurement and its flow Interface and integration issues Chamber logistics Manpower availability Production and installation schedule

Status of LNF production site In August, the set up of the clean room (transfer and set up of tooling) In September-November startup of M3R3 (pre)production: 4 final chambers done (two more under construction) 2 chambers tested under beam : choice between double and single cathode readout test ASDQ vs Carioca Several upgrades of the tooling done and to be done (automatic gluing, more HV bar gluing tables, etc...) A lot of effort in finalizing QA/QC tests and in optimizing the work flow (this has still to improve) The production speed was limited by material availability and to several operations we plan to do in outside company (e.g. components on HV bars)

EDR recommendations 1.A small ‘pre-production’ series should be constructed and tested for each chamber type… The goal was to build and test 4 final chambers: we succeeded in building them, but due to time shortage, and many other commitments (…and a small accident…), only 2 were (nearly) fully tested 2. At least one of these pre-production chambers of each type should have undergone a successful ageing test … This has been done with LNF prototypes in Casaccia. This item has been discussed at length in CERN PRR and will be not treated here 3. The opening of the chambers should be exercised. In fact, the reviewers are mostly worried about the proposal to close two of the three chamber types by gluing… This will be discussed later

4.A wire replacement procedure should be defined and tested for each chamber type. This happened several times and will be explained in the afternoon 5. At nominal gas flow rate, the eventual formation of ‘pockets’ should be checked by efficiency mapping, especially in the case of the longest chamber type. We did uniformity checks and no particular problems appeared 6. As the gap size is probably the most critical parameter for pulse height uniformity, an effort should be made to produce panels of best possible flatness. This will be reported later 7. The sagitta of the panels due to wire tension should be measured, for those panels carrying wires only on one side. Calculations and direct measurements show no sizeable effect

8.The precision of the wiring should be checked on all pre-production chambers. This has been done for the pre-production 9. Gluing should be handled with the utmost attention, with well tested, constant procedures, in particular under <50% humidity … Does not represent a problem and its automatisation is under way 10. Chamber materials and components (panels, bars, wires, glue, resistors and capacities…) should be identical as much as possible for all chamber types. Largely achieved (already discussed at CERN PRR) 11. A well-defined testing procedure during production should be established with the pre-series, including some final two weeks of operation at nominal voltage with final gas mixture and flow. Fully done for 2 chambers, under way for the remaining On the basis of the experience gained with the pre-production series, the production schedule should be re-evaluated … This item will be discussed later

Chamber gluing and its reliability In the period , 11 MWPC chambers were built in Frascati of various dimensions (1.5/2.0 mm pitch, 6 of final size) and all the chambers have been glued and built with similar techniques None of the 960 wire pads of 9 chambers (some 15,000 wires), tested under HV showed problems so important to need a reopening of the chamber In these chambers we observed that after few weeks of constant gas flowing also the wire pads that initially were “more sensitive” to HV, recovered and could be operated at the same HV as the others In the overall design we considered of utmost importance the availability of the access to single pads: we believe this is mandatory for a detailed tracking of problems (especially before chamber closing) and even afterwards, in case a single pad shows some HV-weakness, it can be re-routed on a lower-HV line (the so called “hospital channel”, which we foresee in our layout), without spoiling the overall chamber efficiency and without the need of reopening (or worst) throwing away a full chamber

A stressing HV test should not be performed in the presence of humid gas, such as open air during their construction in the clean room We experienced that only after a very long (several weeks) training with increasing steps in HV and maintaining always a low current limit (in the range of nA for a gap of a big chamber), the chamber can reach operating voltage well beyond its working point The first two final M3R3 chambers (C001-C002) were kept for 3 weeks at 2.75 kV (200 V inside efficiency plateau) with currents of few nA/gap We observed that a resonably fast and simple HV test (few hours, current limited to 200 nA per wire layer) during the production in the clean room is able to spot problems (see Carlo’s talk) On the experience gained in two years of MWPC construction, we believe that, once reasonable HV QC tests have been performed, the chambers can be safely closed with a definitive gluing

Status of panel production It is going on (300 for PNPI for INFN) at a rate of 25-30/week for a single mould (yesterday, 130 done, 6 discarded) See Carlo’s talk for details on planarity measurements Rome 2 is setting up the automatic measuring device at the company New moulds (M2-3, M4-5) under construction (one ready by Christmas) The final set up (with 3 moulds) foresees 20 panels/day (total no. of panels 5360 >> 270 working days + spare) A detailed production plan for panels has to be setup to ensure continuity for various production centers We are planning also a clever scheme for expedition of panels to CERN/PNPI to minimize the number of transports and the number of boxes

Program outline Carlo – Construction procedures, travellers and QC/QA Davide – Source and cosmic ray test stands Gaia – Test beam on M3R3 chambers >>> break Alessio – Access to chamber construction information Adalberto - Interface and integration issues Pierluigi – Material procurement, logistics, manpower, production schedule >>> lunch Visit to production site