LAUSR

With the discovery of the Higgs boson at around 125 GeV, a circular Higgs factory design with high luminosity [Formula: see text] is becoming more popular in the accelerator world. The Circular Electron and Positron Collider (CEPC) project in China is one of them. Machine Detector Interface (MDI) is the key research area in electron–positron colliders, especially in CEPC. Since the [Formula: see text] beams collide at the Interaction Point (IP) with a horizontal angle of 33 mrad, the horizontal trajectory will couple to the vertical. Due to the solenoid and anti-solenoid combined field strength quite high, the maximum could be up to 4.2 T, the transverse magnetic field component is also quite high. Thus synchrotron radiation (SR) from vertical trajectory in combined field should be taken into account. And also synchrotron radiation is an important influential factor in the collimator design of CEPC MDI. These two effects are analyzed in this paper.