件名 : RE: SCT GeoModel (Mon, 18 Sep 2006 16:41:20 +0900 (JST)) 送信者: kondo@post.kek.jp 宛先 : Pat　Ward [cpw1@hep.phy.cam.ac.uk] Tricoli,　A　(Alessandro) [A.Tricoli@rl.ac.uk] Cc : S.Haywood@rl.ac.uk Taka.Kondo@kek.jp --------------------------------------------------- Dear Alessandro, Pat and Stephen, Thank you for your mails from Alessandro on 4 Aug and 12 Sep, as well as from Pat on 21 Aug and 14 Sep. Let me apologize all of you for my slow response. Took time for me to digest Alessando's great work and also to trace back what I have done a year ago (I was younger!). I noticed and felt a bit shame that my work last year was far from completion. I have to express my deep appreciation to Alessandro for finishing up with comprehensive spreadsheets! It must have been a lot of work with pain in the neck! Also it was a surprise of my joy to receive a mail from Pat with very detailed numbers of comparisons with constructive and useful proposals. I agree with Pat and Alessandro that changes should be made after we all agree. Below are my comments after my agony of a few days in understanding the spreadsheets of Alessandro and recovering my dim memory on my past works. Notes for discussion on new barrel services geometry. CPW 18/8/06 ==================================================== Dogleg ====== Current Alessandro ------- ---------- Thickness/mm (r) 1.0 0.34 Length/mm (phi) 36.0 76.8 Width/mm (z) 30.0 26.0 Volume/cc 1.08 0.78 Mass/g 6.9552 5.71 Density/(g/cc) 6.44 8.41 * Propose to keep current dimensions and position but update mass and composition. Length cannot be extended without overlapping cooling pipe. -A.T.: the thickness value I chose (0.34mm) includes only the power tape layers, does not take into account the opto- package, fibers etc. for which I could not find dimension information. So I am happy to have it extended to 1 mm in r. The length in phi in the current simulation seems rather short to me but this value has probably been chosen as the maximum allowed to avoid clashes. So that's fine. -T.K.: The dogleg length in phi of the current simulation was determined by watching page 1/20 of http://atlas.kek.jp/si-soft/geometry/SCTBarrelMount.pdf, in which you see most of dogleg parts are within 30mm in phi. (BTW, the current length (phi) is 30.0mm and width(z) is 36mm.) We can make phi length longer without clashes, though. * Why is new mass lower? This is 'dogleg+top bracket' option. -A.T.: the lower mass in my computation is due to the placement of the "module clips" and "dogleg clips" into the "cooling block" model, the placement of the "lmt i/f board" and "redundancy arms" in the "straight harness" model and the addition of the opto-fibres in the "dogleg", not present before. -T.K.: I agree with AT. It is better to move both clips to the cooling block. Thank you for adding opto-fibers which was missing from my work. Cooling Block ============= Current Alessandro ------- ---------- Thickness/mm (r) 1.5 5.0 Width/mm (phi) 8.0 8.0 Length/mm (z) 62.0 62.0 Volume/cc 0.74 2.48 Mass/g 2.418 3.62 Density/(g/cc) 3.25 1.46 * Suspect mass difference because Alessandro has included solder, clips, etc. and current value only include block (current material = Al). Is this so? -A.T.: Yes, I think so too. I cannot find any Taka's spread sheet with the list of items that enter the cooling block, but from the composition (only Al) and the weight it seems so. In fact in my calculation, the cooling block itself weighs 2.24g the rest is due to solder (most of the weight), shunt shield, screws and clips. -T.K.: Again, thanks to Alessandro, my incomplete work was completed by adding solder, screws etc. * Propose to keep current dimensions and position but update mass and composition. There is no room to increase thickness. -A.T.: the thickness value I quote is what I found in drawings, but I guess in the simulation has been reduced to avoid clashes. So that's fine. -T.K.: Yes, in the simulation I had to separate the cooling block (attached to each module) from the cooling pipe which is one in row, the reason why the cooling block is made to be thinner in simulation. Cooling Pipe ============ Current Alessandro Drawing ------- ---------- ------- Radius/mm 2.0 2.1 Length/mm 1571.76 1471.6 Radial position/mm (3) 304.8 306.9 307.1/309.7 (4) 375.7 377.9 378.0/380.6 (5) 447.4 449.9 449.7/452.4 (6) 518.1 520.9 520.4/523.1 * Current positions (estimated from entry points of particles) are 2-3mm inside values suggested by Alessandro and drawings. Propose to leave them there - moving likely to cause huge problems. -A.T.: I don't understand the values in the first two rows under "current" and the "radius/mm" value under "Alessandro". (?) * Length will be updated to 'whatever is convenient'. I think the radius can be increased, but am not sure it is worth it. Mass and composition will be updated. - T.K.: If the radius is increased to 2.1mm, the pipe edge becomes closer to the cooling block for the lower case. Let not change it. As I said, in order to separate the cooling pipe from the cooling blocks safely, I had to move the cooling pipe about 1.5 mm farther. I got 305.8mm instead of 304.8mm (B3 case) from my drawing of http://atlas.kek.jp/si-soft/geometry/rphiView-B3lower.pdf. Can Pat check it again though it is a tiny difference? Bottom Bracket ============== Current Alessandro ------- ---------- Thickness/mm (r) 4.0 3.2 Width/mm (phi) 8.0 7.5 Length/mm (z) 51.0 54.0 Volume/cc 1.63 1.30 Mass/g 4.94496 2.68 Density/(g/cc) 3.03 2.07 * Why the mass difference? Think Taka includes an 'interface PCB' and Alessandro does not (I think this is in Alessandro's harness). This needs checking. -A.T.: it is true that the "interface PCB" is placed in the harness in my model, but this accounts for only 1.43g extra, which added to 2.68 g gives 4.11 g. That means that 0.84g are missing. I notice that in Taka's excel sheet in http://atlas.kek.jp/si-soft/geometry.html the "bottom bracket" is actually 4.36g. The difference wrt my estimate is only 0.25 g in this case. Going through Taka's calculations I notice that he used both THIRD MOUNTING POINT UPPER and LOWER, whereas I only used an average between the two, since (if I understand correctly) either the lower or upper third mounting point is on each bracket assembly, depending whether the module is in the upper or lower position. Furthermore, I have one more screw (M1x4=0.027g) than Taka. In conclusion the differences between my description and taka's description are minor, whereas I do not know where the current value in the simulation (4.945g) comes from. Any idea Pat? -T.K.: (1) The interface PCB is actually on the cylinder attached to the power tape. Thus Alessandro's model of including it to the Harness is better. I accept this change. (2) It is my mistake. I double counted THIRD MOUNTING POINT. Thank you for pointing it. About the screws, I do not find Alessandro's additional screw of Third Point Peek Finger Screw (M1x4) (<- material is Stainless Steel??) Please take a look of page 18/20 of http://atlas.kek.jp/si-soft/geometry/SCTBarrelMount.pdf in which I find one SS screw of M1x4 and one Al screw of M1.6x6. Can Alessandro check the related drawings? (3) There was a mismatch between my drawing and my spreadsheet of http://atlas.kek.jp/si-soft/geometry/topView-B3.pdf ->51x8x4 http://atlas.kek.jp/si- soft/geometry/BracketDoglegPowerTape.xls --> 60x15x1.6 As you pointed, they are inconsistent. Let us stick to 51x8x4 and change density. * Propose to keep current dimensions and position, update mass and composition. -A.T.: that's fine with me. -T.K.: But after we identify Third Point Peek Finger Screw (M1x4). -T.K.: Now this may be new. As I remember correctly, two sets of screws and nuts for each bracket were added in the middle of cylinder assembly around Spring of 2004. These sets of screws and nuts (imbeded into the Cylinder) were added because some of the brackets were not fully glued on the cylinder. These screws and nuts must not be written in the original drawings. I would be happy if Alessandro could ask this matter. If I can find these sets at KEK, I make a weight measurement and let you inform the results. Harness (Power Tapes) ===================== Contained within a volume: Current Alessandro ------- ---------- Thickness/mm (r) 1.221 1.97 Width/mm (phi) 21.0 24.66 Length/mm (z) 1571.76 1423.1 Mass/g 33.5025 93.4 * Within this volume are 2*6 tapes (each thickness 1.221/6mm) stacked in r, running from the interlink to each dogleg. Propose to keep this structure, but increase tape thickness (to ?) and reduce length to make end at end of cylinder. -A.T.: I agree. The thickness is difficult to model since on top of the tapes there are the fibres and the clamps. All these items have different volumes along z. Any value of thickness between 1.22 and 2 mm would be fine as long as they don't cause any clash with other volumes. -T.K.: Alessandro's NarnessSplit model with N1 to N6 requires quite a change in programme. For minimum changes, it may be better to keep the current dimensions (except thickness which you can increase without clashes). But as Alesssandro points out below, the biggest contribution is from mass is from the "permanent clamps", and in that case we may better switch from my power-tape model to N1-N6 model for more realistic mass distribution. Let me draw a picture for myself and think it for decision. * Why now so much more mass? Seems to be because the current 'power tapes' include only power tapes, whereas Alessandro's harness includes fibres, interface PCB, connectors as well. The power tape component of this is 33.34g which is similar to current power tapes - is the rest really so much more? I think some of the stuff Alessandro has included in the harness has probably been included by Taka in the dogleg or brackets - they should check, if they haven't already done so. In which case, do we want to move it into the harness, smeared out along z, or keep it in the doglegs and bracket, concentrated in z? -A.T.: Yes, most of the difference between the current value and my value for the harness is due to the absence in the current simulation of the "permanent clamps", 2.1g each (25.82 g per row) the interconnects and the fibres. Furthermore, as already mentioned, some of the connectors and the i/f PCB are placed in the harness in my model, whereas are in the dogleg in the current simulation. So the mass difference is explained. I have no strong arguments to keep the i/f PCB and the connectors on the harness, but I don't see any big impact on the simulation either if we move them into the dogleg: in fact in the simulation the straight part of the harness is split into 12 subsections along z (as you can see in the "HarnesSplit" sheet) so that the masses of these components are smeared only over a small area. However I am happy to follow Taka's approach if you think it is more appropriate. -T.K.: Thank you again to Alessandro to list up all missing items. Just like Pat, I am a bit surprised to hear 25.82g per row by permanent clamps. I am happier if Alessandro can double check it. * Should the interlink volume be at |z| = 765, rather than current position just inside thermal shield? And where should thermal shield be? -A.T.: Stephen and I just started looking into the interlinks and thermal enclosure modeling, so we will get back to you on this soon. Cylinder, Flange, Clamp ======================= * Propose to change geometry here to match Alessandro's dimensions, layout and materials, except that the clamp will start outside the auxilliary layer, i.e. there will be a 2mm gap between the harness and the clamp (in r). -A.T.: OK. -T.K.: OK. Cooling Inlet/OutLets and U-bends ================================= * Propose to implement a simplified model of these in the first instance: a tube with r_min = r_max of clamp r_max = r_min + 10 mm extending in z from the end of the modules (z = 747mm) to the end of the barrel (z = 765 mm). -A.T.: OK. At some future date, it would then be possible to split this tube into segments with alternate segments filled with different materials to simulate the in/outlets separately from the U-bends. And even to put smaller volumes inside the segments if necessary. But the overall envelope would be the same at each end, and the cooling pipe just runs between these envelopes. -A.T. I think it is a good strategy. -T.K.: A agree. ------------------------------------------------------------ In addition, for material composition, Alessandro is proposing to use matter-level breakdown like Al, Cu-Ni, CFRP, Kapton ...... instead of my atomic-level breakdown to H,C,O,Al...... I agree with the poposed matter-level breakdown, because it is more transparent and easy to understand. I would behappy if Pat can think about this change, hopefully easy. I would be happy if I receive further comments from all of you. BTW, I am coming to CERN for nextATLAS Overview week at CERN in the week of October 2. Best regards, Taka