Minutes of FT upgrade meeting held on 26/11/98 ============================================== Present: Steve Burke, Tim Greenshaw, Rob Henderson, Derrick Hill, Graham Hough, Gary Markey, Dave Sankey, Terry Sloan. Actions from previous meeting ----------------------------- Tim Greenshaw ------------- Tim explained that the magnet support situation has been cleared up. Karsten Gadow's torque constant, used in the calculations, was too small and the amount of free space contained a safety margin of 8mm. Correcting these two figures in the calculation makes it possible to support GO. There is no need to have methanol in the proposed planar test gas (Ar:CO2, 90:10). Derrick has brought some flow meters with him to Daresbury. Scott Kolya has indicated he would be interested in helping the upgrade by producing a VME based readout system for the planar tests. The drawings of the radial front field formers cannot be located and are to be re-created from spare front field formers. The front field former assembly will be constructed as far as is possible before the HERA upgrade, minimising the work that must be done during the shutdown. Eram Rizvi has expressed interest in working on the Upgrade software. However, it is possible that he will be asked to join a different project by John Dainton. Tim went through the finances. One potential major cost, the preparation of the premises for the construction of the planars, was not accurately known at the meeting, but figures were expected within a few days (see Gary Markey's comments below). An up to date summary will be given at the next meeting at which point a decision will be made on whether to purchase walls (Nomex + PCBs) for two extra chambers. Action Tim - Produce new budget summary when figures from Gary Markey available. Graham Hough ------------ Graham showed the latest schedules, which will soon be available on the web. There was some discussion as to whether the time allowed for building the planar chambers could be shortened, but it was stressed that this includes time for testing. Tests necessitate gassing up the chamber, getting HV on it and (for the first chamber) debugging the test system itself. These are all time-consuming activites! The time required during the HERA upgrade appears to be somewhat more than is available to us working 5 day weeks. Ray Thompson says that experience from previous rounds of chamber construction suggests one in ten cells will fail and need repair work. Derrick will provide materials (wire, pins etc) for a dummy construction run so that the construction team are ``up to speed'' when the genuine article is to be built. An additional set of PCBs and Nomex panels has been foreseen for this purpose. The test PCBs have yet to be closely examined (microscope/magnifying glass) and HV tested. Tim will get this done at Liverpool. The space originally foreseen for the planar construction is not available and this means that the SLAC tent cannot be used. Alternative premises were inspected during the course of the meeting. Action Tim - Organise inspection/HV testing of PCB test piece. Derrick Hill ------------ Derrick explained his latest attempts at getting pins out of Medelec. (The stones to which he has applied this procedure are all now bleeding profusely.) Two (2) pins have now been promised ``immediately''. Further enquiries are concerning possible alternative manufacturers are being made. There was some discussion about the dimensions of the pins and the reasons for their complicated shape. The feeling was that this arose because it was necessary to ensure that the pins could be pushed into the noryl end pieces without exerting too great a force (implying that the length of the pin with diameter matching the internal diameter of the hole in the noryl could not be too great; the rest of the pin which must go into the noryl must have a smaller diameter). There must also be a collar to prevent the entire pin slipping into the noryl. The ends are bevelled to make insertion of the wires easier. The diameter of the end which enters the plugs attached to the sense/field wire HV cables must match the diameter of the plugs and also there must be small diameter section at which the crimping is done. This gives rise to a structure as follows: |--------| |------------| | |--------------| |------------| | |------------------| \--------------------------------------------------------------------/ /--------------------------------------------------------------------\ | |------------------| |--------------| |------------| |------------| | |--------| drift noryl noryl collar plug crimp volume loose fit tight fit None of the diameters have to be the same, though the construction of the pins would be much simpler if they could be made to be so. If anyone can give more information on the reason for the structure of the pins, please do so! The drawings of the sense wire pins at Daresbury were found to be incorrect. Derrick reported that accumulation and construction of the test equipment was proceeding. The wire tension testing equipment used for the construction of the ZEUS CTD can be used for our tests. The ``testing documents'', detailing the tests made on the original planars, are to be sent to Daresbury. Action Derrick/Graham - Ensure drawings of pins correct. Dave Sankey and Derrick ----------------------- Dave and Derrick reported that five pre-amps have arrived and have been tested by hand. As far as can be seen thet are functioning, but it cannot be checked whether they are within spec. until the automatic test procedure can be got working. At the moment this is still proving difficult. Action Dave/Derrick Continue working on test software. Support of FT ------------- Graham showed drawings of the current FTD support feet. The alternatives available allowing a forward shift of 6cm were discussed. These are: 1) Move the current feet to the central U channel. This may work, but leaves a large proportion of the FT's weight ``hanging'' in front of the foremost support. 2) Construct an extension which can be bolted onto the front U channel onto which the front feet can be attached which shifts the feet back by the necessary 6cm (plus a little for safety?). The problem here is that it must be ensured that the extension does not obstruct cables coming out via the feedthroughs. Both of these options require further study, 1) to determine if the FT is left sufficiently stable and whether the load on the central U channel and feet is acceptable, 2) to check that the space for the extensions is available. Note that both sides of the tank must be investigated as the feedthrough positions and wiring are not symmetrical. Action Graham - Examine above support options. New construction site --------------------- Gary Markey showed us the room in which it is now proposed the planars be built. It was agreed that the room required a thorough clean, new flooring, re-painting and the installation of a filtered air supply. The actual wiring will be done in a small tented area within the room. Gary will e-mail costs of the proposed work to Tim for circulation with the updated budget. Action Gary - Cost work on construction space. Six or eight wires ------------------ HV/Readout ---------- Dave reported that there are no problems with going to 8 wire cells as far as HV and readout hardware are concerned. In particular, there are enough FADCs and enough spaces in crates for them to go into. Mechanical problems ------------------- Graham explained that carrying the additional load in going from 4 to 6 wire planars had required an increase in the thickness of the Noryl end pieces from 10mm to 15mm to ensure the distortion with 6 wires was not larger than that with 4. Going to 8 wires requires the thickness of the Noryl to be 20mm. There should be no incidental problems arising from this in the operation of the chamber (the space for gas flow should be adequate, for example). Care must be taken with the design of the pins. They must be lengthened, but we must make sure that they can still be inserted in the Noryl without exerting undue force. The length of the section which fits tightly into the Noryl should probably stay about the same. An alternative is to machine the Noryl end pieces to ensure easy insertion of the pins. During the discussion, the problem of whether the dowels which pin the Noryl in position are strong enough to carry the additional load due to eight wires was raised. It was decided some tests/calculations were necessary to clarify this. Graham showed some FE calculations of the distortion of the Nomex panels under the load of eight wires. This makes it desirable to increase the thickness of the thinner panel from 3 to 5mm. As this has no significant ill effects and allows the panel flatness tolerance to be more easily met, the decision was taken to use 5mm for either 6 or 8 wire planars. Action Graham - Do dowel tests and calculations Software considerations ----------------------- There are no major obstacles associated with using 8 instead of 6 wires. The warning was given that wire numbering schemes should be chosen to allow 8 wires, and also that the radials eventually be replaced by planar chambers. Next meeting 10/12/98, 11:00, Darebury.