Beam Pipe Support ATLAS Composite support tube with

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

Beam Pipe Integration ATLAS • • • 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 d n ea p am e B ipe ort p p Su e ip mp ort p p Su a e d. B n a ice rv Se Pixel Detector ic rv Se 2

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

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

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

ATLAS 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

ATLAS 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.

Next Steps ATLAS • • 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. 8