BCM Overview Placement such that system is sensitive to all types of beam accidents. => 2 independent subsystems Halo losses inside the Pixel volume ie interactions with the Be beampipe section Showering from outside the TK volume Concerns for interference Subsystem 1: One as close as possible to BP Target = same radius as the inner layer of the pixel barrel Target = 8mm from beampipe at final position With no FPix squeeze dist= 14 mm With FPix squeeze dist =23mm Subsystem 2: At larger radius Not at risk of interfence with BP or FPix Support services Placement of frontend electronics and services must be adjusted once rail system agreed upon ( BCM treats this issue as secondary, although limited space between BCM rail and FPix service tube feet) Beam Pipe support wires Must respect envelop around wires. At present the BP group is requesting an envelop of R= 15mm

Concerns Lateral movement of FPix service cylinder toward beampipe “cuts off” space for BCM insertion Cabling FPix should done with FPix in final position and before beampipe hook up BCM and FPix should be independent system There should not be any holes in coverage of the FPix

The problem: BCM and FPix envelopes overlap at rear (z=~2 The problem: BCM and FPix envelopes overlap at rear (z=~2.6m) of FPix service tube

Possible “solution”: Very difficult Kinked BCM rail, straight rail after kink

Rotating hinged on the front foot =» outer edge move ~2.5 mm D = 166mm d=~2.5mm Question of gaps in coverage Rotating hinged on the front foot =» outer edge move ~2.5 mm

Full Squeeze

10mm Squeeze: 1st Layer

10mm Squeeze: 2nd layer

10mm Squeeze: 3rd Layer

Notes from Kurt The reason for the final rotation of the disk structure was of course to get the disk plane perpendicular to the beam. The advantage was also that from the rear face of the barrel service tube to the rear face of the disk cylinder there was some lateral room which facilitates the sorting of cables/pipes going to the patch panel PP0. No (or only partial) final rotation would on the other hand facilitate the mounting of the horizontal beam pipe suspension. No (or only partial) final rotation will of course complicate a lot the software describing the geometry (track reconstruction from hits, alignment....). Also one should check whether there is still overlap of the two half-disks of the most remote disk. My first guess is that it should be possible to omit the final rotation. It would imply a correction of the lengths of cables/pipes from the disk structure's end flange to PP0 which have been determined so far assuming full rotation. For a more educated guess, I should have a layout of the rear face of the disk cylinders as it is foreseen now, in particular the arrangement of cables/pipes exiting the rear end flange of the disk structure.

From Bruno

Comments on the FWD pixel track transversal movement in the rail slot of ~35 mm, hinged on front foot with a lever arm of 2209mm: