Design of an ultra-thin, radiation thickness minimized, metallic cryostat for a 2T/4m free bore detector solenoid

A 2T, 6m long, 4m free bore superconducting solenoid is being designed for the so- called IDEA detector for probing electron-positron collisions at the proposed Future Circular Collider at CERN. In order to drive the cost of the magnet down, the solenoid is positioned around the inner tracking detector for which presence of the magnetic field is mandatory. This approach reduces the dimensions of the magnet roughly to half bore size, and therefore significantly the cost. However, the new position adds a new and demanding requirement solenoid and cryostat designs as they need to be as thin and radiation transparent as possible. A full mechanical analysis of the cryostat including all the mechanical loads is performed to the minimum effective wall thicknesses while respecting structural design norms. We present a novel design of a cryostat using alternative approaches such as corrugated walls honeycomb-like structures and compare to a classical solution of using solid uniform plate.