ATLAS (A Toroidal Lhc ApparatuS)

The ATLAS Silicon Trackers lie in the centre of the ATLAS experiment. They use silicon solid state detectors to determine the properties of the charged particles produced by the colliding beams. The following highlights some of the areas where STFC Mechanical engineering was used;

Structure: There are very demanding requirements:

• Stiff and extremely stable structures to accurately position the detectors and support power, cooling, and readout services.
• These must be constructed from non-magnetic materials and be radiation tolerant to withstand 10yrs+ of operation.
• The absolute minimum amount of material must be used since it will absorb particles and make the data less accurate.

A stiff and lightweight CFRP sandwich structure was produced giving a positional stability of better than a few 10s of mm over a day with good radiation durability.

Wheels: A set of 9 structural CFRP discs supporting individual silicon detector modules and all the electrical, data and cooling services.

Environmental housing: This enabled the tracker to be a thermally neutral sealed containment for N2 dry gas purge while meeting grounding & shielding requirements.

Services arm: The superconducting ATLAS end cap magnets require copious quantities of cyrogens and other services. These services required a specially designed 18 metre long flexible support arm.