Environment: For assembly, installation, operation and maintenance we need a temperature stabilised, humidity controlled environment. Might want to flush the surfaces/containment with dry nitrogen. Temperature gradient towards final installtion and running should be kept small (this might be an issue if parts of the detector are close to the cooled ECAL or magnet, or if we want to run colled detection devices ourselves. Thermal expansion coefficients for all our materials need to be check (esp. holding structure with respect to radiator materials.)) That means we might have to think about temperature control as well. The real power consumption and heat load needs still to be investigated.

Maintenance: This subject is devided into two parts, regular maintenance operation and replacements and repairs. I figure, we do not need to shedule regular maintenance intervals, servicable parts (e.g. filters for a dry nitrogen system) can be arranged on the outside (either On-Detector o Off-Detector). Replacing parts will be more difficult as they most likely are In-Detector. If the readout is inside the yoke of the magnet (as in the current desing options), repairs require opening the magnet and retracting the endcap ECAL. The endcap DIRC might have to slide out as well before it becomes accessible. Given an average amount of failures, this probably means that the endcap DIRC has to be moved out during the detector downtime for minor repairs and replacements.

Space requirements:

Storage: After assembly only minor space is needed for storage of tools, replacements etc.

Mounting area: detector of about 2m diameter, accessible from all sides during assembly -> 40 m^2 for about 3 months, dust free area. Ideally, this should be done at GSI to reduce transport riscs. Smaller parts (e.g. focussing light guides, PMT boxes ...) will be tested be assmebled outside (Glasgow, Edinburgh)

Electronics: digitisation takes place In-Detector, receiver and LV/HV crates outside (probably 1 19" rack, at least 2-3 9U crates). As we are dealing with digitised signals outside of the box, distance of the receiver crates is less critical. Might need some On-Detector repeaters.

Utilities: only necessary for dry nitrogen (may be centralised system with Barrel DIRC), cooling should also come from central supply.

Mounting: self contained vessel assembled outside (lying flat, then turned upowards for installation), slide insde detector from upstream part on rail system. This should already provide coarse alignment. Fine adjustment by optical marks on the surface which in then in turn are referenced to the interior (this require survey during assembly). Otherwise, 'just' cabling up. This will require a 1t crane to move the detector to the rail system. Number of support points can be just a few, depnding on the design of the box

Ressources: dry nitrogen supply lines (?), cooling

Cables: HV supply lines for ~250 photon detection devices (might be much less for semiconductor readout), 250 flat ribbon cables for digitised signals, LV supply lines for In-Detector electronics (I would like to avoid having power supplies in the In-Detector Area), probably some cooling lines or vents to get rid of the processor heat. If the readout and digitisation is inside light tight box, some kind of cooling will be needed. This could come from the central cryo system or placed on the outside of the box. Probably a good solution would be to have a limited number of extrusion points symmetric around the detector (4-8).

Support: The endcap dirc will weigh about 750 kg (200 kg for a fused silica disc, similar amount for support structure, plus light guides and readout). It should be a self supporting frame which needs to be attached to probably the magnect housing and aligned with respect to the beam line. The whole support probably should move out on some kind of rail system for maintenance work. Any veto areas will depend on the design of the support structure. As this will be a light tight box with rather thin walls in the active area of the detector, it is to be expected that only the rim will allow for sufficent rigidity to hold anything of subtantial weight or force. For the moment: central area, 1.20 m diameter
Topic revision: r2 - 18 Jul 2006, BjoernSeitz
 
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