Speaker
Description
The Future Circular Collider (FCC) electron-positron version may be the next step towards a next generation of particle colliders. It may include an Experiment for probing ee+ collisions using the IDEA (International Detector for Electron positron Accelerator), or similar, detector requiring a solenoid enclosing the inner tracking detector. An innovative 2 T superconducting solenoid with 4 m bore and 6 m long, has been accepted as baseline. Positioning the solenoid in between tracker and calorimeter requires an ultra-thin and highly radiation transparent cold mass. Likewise, a thin and radiation transparent cryostat is needed. The set value for the solenoid’s maximum radiation length is 1*X0.
The cryostat is designed as a sandwich of thin Aluminum alloy inner and outer shells eventually locally reinforced, for achieving vacuum tightness, and layers of innovative insulation material providing lowest thermal conductivity and sufficient mechanical resistance. Cryogel Z, a composite blanket of silica aerogel and reinforcing fibers, has a density of 160 kg/m3 and would allow a 250 mm cryostat thickness featuring a heat load of 400 W on the cold mass and 10 kW on the thermal shield. As an alternative, glass spheres (e.g. K1 type, manufactured by 3M, with a 65 μm diameter and a 125 kg/m3 density), or similar material, can be dispersed between the vacuum vessel thin-walls providing structural support.
Besides the cryostat conceptual design, we outline the setup developed at CERN to measure the thermal conductivity of the above-mentioned materials, present the test results and provide a design of the solenoid cooling system.
