ATLAS Pixel Detector BCM Signal Cable October 13, 2005 E. Anderssen, LBNL

ATLAS Pixel Detector October 2005 E. Anderssen LBNL Cable Model Circle next to cable is ghosted power cable—5.5mm diameter—cable since modified to 4.8mm dia (larger than in figure All Bends are planar—some length could be saved with spiral bends Somewhat complicated shape, less than 270degrees worth of 25mm radius bends Cable spec says 12mm is limit for ‘multiple turn bends’ Modeled Both 19-S01 and R01 SMA Straight Pin connector Current length, ref surface to ref surface of SMA is 1430mm as routed

ATLAS Pixel Detector October 2005 E. Anderssen LBNL Complicated Joggle Bend at BCM End 11mm straight section before first 25mm bend for S01—Bend Starts immediately for R01 (see figs later) 12mm bend required to ‘shorten’ radial incursion of SMA Have also modelled all at 25mm Changing other bends to 12mm bends would move connector out radially another 7mm (see next slide for why), but only possible with S01 (marginal with 190 series, was possible with 120 series) Potentially a spiral bend would save similar radial distance and allow larger radii, but too difficult to model effectively 25mm 12mm

ATLAS Pixel Detector October 2005 E. Anderssen LBNL SMA connector wants to extend into box… This is older figure, have since been given model of Box with SMA What I’m trying to show is that assuming reasonable bend limits, this is where the connector ends up—inside the box The box needs to move along the connector axis to actually work with any straight connector (see later slides) As per previous slide, some distance can be taken up with tighter or more complicated bends (hard to model, but maybe possible to test with actual cable) But likely that only gets you half-there Box also needs to move in for other reasons (later slides) 15mm

ATLAS Pixel Detector October 2005 E. Anderssen LBNL Why the complicated curvature bends at BCM Figure shows original cable model (heliax with simple bend) Old cable without joggle, intersected Service panels—joggle is needed to bring cable closer to centerline of BCM/Longeron to clear service panels Power Cable, though larger in diameter than the Signal Cable, is closer to center, and likely does not need joggle I have not modelled the power cable yet The Red ellipse details the cable running thru the edge of our Inner Service Panel

ATLAS Pixel Detector October 2005 E. Anderssen LBNL Another Good Reason to move in Radially… The object in Red is the Service Panel structure (ISP) The Yellow field bounded by the green part is a routing channel for my environmental services While the BCM Box and Mounts do not directly hit anything in my model… –They are a bit too close for my comfort… –The Accuracy we’ve assumed for their mounting is low, so any deviation risks interference Moving them in radially at least 5mm is required, 12-15mm is conservative, and better for the cable –Direction of move is along axis of BCM Box, root 2 of that radially—see later slides To be clear—box needs to move in radially along its axis at least a few mm. 1mm

ATLAS Pixel Detector October 2005 E. Anderssen LBNL S01 connector requires less inward shift of Box 12mm 7mm 25mm all radii bend, requires 5mm more along box axis Only box moved in illustration, clips should follow 12mm all radii bend, requires only 7mm move along box axis Bends are tighter, and maybe too much for Connector 25mm 12.5mm

ATLAS Pixel Detector October 2005 E. Anderssen LBNL R01 connector requires More inward shift of Box 22mm 17mm 25mm all radii bend, requires 5mm more along box axis 12mm all radii bend, requires 17mm move along box axis 25mm 12.5mm RO1 is essentially 10mm longer, and more rigid than SO1, it takes more space, and might require more drastic bends in cable near the connector to actually reach longeron run.

ATLAS Pixel Detector October 2005 E. Anderssen LBNL Change in Radius as function of Connectors Measured innermost corner of box as currently modelled Would propose to move box 12-15mm (boxed dim), making for mm radial box position Nominal Box Position Beam Axis 59.3mm55.0mm48.0mm 7mm 17mm 12.5mm Bend Radius Box Position Nominal Box Position Beam Axis 59.3mm 51.5mm 44.5mm 12mm 22mm 25mm Bend Radius Box Position S01 R01 S01 R01

ATLAS Pixel Detector October 2005 E. Anderssen LBNL Measured Nearest Edge to Nearest Edge Previous slide—this measurement/2 Shown here is R01 Slide just for ref

ATLAS Pixel Detector October 2005 E. Anderssen LBNL Full 22mm incursion (R01 w/25mm bend radii) Would still prefer S01, but it does show that even 22mm in, there is no chance of Hitting Beampipe BP Bellows here is innermost interference, B-Layer is even closer to BP Limits that I don’t understand have to do with electronics radiation resistance IF 22mm is OK (shoot for 25?) then RO1 can be made to work IF not, and SO1 is not an acceptable option, Then must persue R71 option—next slide for ref RO1, to me is potentially too rigid to know if I can successfully route with any less than this

ATLAS Pixel Detector October 2005 E. Anderssen LBNL GORE connectors for G5 cable SO1 is the most svelte, and can start bending 10mm sooner than RO1 If 22mm movement is not good, and SO1 is unacceptable, then need R71 R71 will let a swooping bend with large radii approach the Longeron As per previous slide, still do need to move in a few mm in radius, even with R71

ATLAS Pixel Detector October 2005 E. Anderssen LBNL Just some pictures

ATLAS Pixel Detector October 2005 E. Anderssen LBNL Cable Ghosted in under Longeron

ATLAS Pixel Detector October 2005 E. Anderssen LBNL This too could be a spiral bend It is easier for me to rigorously model jogs and offsets as parallel joggles than spiral bends, here the cables only need to get around objects 4mm wide (center-line shift of only 3.5mm). If I didn’t put in the shift, the models would interfere, but real trajectory is likely just a lazy spiral along the green arrow… Power line will be on other side of aluminum inserts, rejoining the signal cable just before penetrating the orange panel (PP1 Cruciform). This will allow each of them to be relieved together and potted through the penetration. I have not designed the penetration, but will shortly, after I model the power cable.