ATLAS upgrade mechanics

Barrel strip stave assembly

The Silicon strip sensors (10×10cm2) are supported on local supports called "staves". These staves are built on a carbon fibre sandwich structure consisting of facesheets made from ultra-high-modulus (UHM) carbon fibre (CF) and a core, which comprises thin-walled titanium cooling pipes embedded in a carbon foam of high thermal conductivity and carbon fiber honeycomb material. This results in a very stiff, low material support structure. A series of full-size stave prototypes for the future ATLAS strip tracker have been manufactured at Oxford.

To save material the Kapton/Copper tapes are co-cured with the CF prepreg to make the facesheets. This technology has been pioneered by our group.
ATLAS strip stave core.
Kapton/Copper low mass tapes co-cured with UHM CF. Front (bottom) and back (top) of the facesheet.

Global barrel support structure

The barrel strip staves are supported by five concentric CF support cylinders. We are participating in the design and FEA studies of these structures, in particular in the interlinks connecting the support cylinders at their end.

Barrel strip stave mounting

We have developed a mount system for the strip staves to the support cylinders, which allows for the insertion of the staves from the barrel end. The support system consists of injection-molded PEEK support points along the inner edge of each stave. To demonstrate the proper functioning of this design we have built a 3-stave sector and studied insertion and locking of the support points in all orientations.
Barrel strip stave mount scheme

We are also studying the deformation of the local supports under vibration and thermal loads using Electronic Speckle Pattern Interferometry (ESPI) and a capacitive sensor system.
Node shapes of strip staves in edge-mounting supports. Comparison of FEA calculations (top) with experimental results from ESPI (bottom) for the first three modes.

Further reading

ATLAS phase II upgrade LOI


Georg Viehhauser