2. ATLAS 1 Beam Pipe Support SCT TRT Side CSide A Services and Beampipe Support Frame Services and Beampipe Support Frame Pixel Detector Composite support tube with integrated rails LBNL responsible for support tube and services structures

3. ATLAS 2 Beam Pipe Integration Service and Beampipe Support Pixel Detector Beam pipe is integrated with pixel detector on surface building. All then lowered. Design requirements from CERN for beam pipe support have evolved over last year but now appear to be nearly final. Design of support and adjustment mechanism being done by E. Anderssen, N. Hartman and D. Uken at LBNL

4. ATLAS 3 Beampipe Support Frame Wires at Z=-800,+800 Fixed Adjustors (no spring) Top and Side Sprung Adjustors Side and bottom (tension limiters) Wire Adjustors Cruciform supports Longerons Service panel Attachment points Reinforcing Longerons

5. ATLAS 4 Geometry at Pixel Detector End No BP Collar Shown Cruciform Support Longerons Beampipe Wire Guide Beampipe shown in extreme off-center position

6. ATLAS 5 Adjustor/Tension Limiter Preload Adjustor Barrel Limiter Spring Wire Adjustor Screw Wire Adjustor Nut Wire Collet & Nut Wire Tension Limiter Plunger Wire Guide

7. ATLAS 6 Assembly of Adjustor/Limiter Unit Tension Limiter Assembled, Spring Compressed Wire Fed Through, Clamped into Collet Wire Adjustor Seated in Tension Limiter Max “IN” Adjustment Max “OUT” Adjustment

8. ATLAS 7 Tension Limiter During Operation, Spring Holds Limiter Plunger Against Preload Adjustment Barrel When Tension Limit is Exceeded, Plunger Moves, Allowing Wire to Extend Under Reduced Stiffness of Spring Electrical Contact Between Plunger and Adjustment Barrel (not shown) signals when Tension Limit is Exceeded.

9. ATLAS 8 Next Steps Design will be reviewed internally by CERN next month. Assuming this is OK, immediate next step is to make prototype of adjustment mechanism that would include short version of support frame. Test out adjustment After that would proceed to final design and then fabrication of the composite support frame and multiple adjustment mechanisms.