Conceptual Design of CEPC Detector Magnet

The circular electron positron collider will measure the Higgs boson properties in great detail. The detector needs a three Tesla superconducting solenoid followed by a muon detector embedded in a flux return yoke. This article introduces the conceptual design of the superconducting solenoid includes two schemes based on Large Hadron Collider and HTS technology. The fundamental parameters and structures of magnets are discussed, and the advancements in electromagnetic design, quench calculation, cryogenic system design, and conductor development are outlined. The conductors used in the two schemes, the aluminum stabilized NbTi/Cu Rutherford cable and the aluminum stabilized stacked REBCO tape cable, are also under development. The viability of the first-ever HTS aluminum stabilized cable proposal is confirmed, and the technology of coextrusion aluminum coating has been preliminary mastered.