FCC-ee interaction region backgrounds

Abstract

The FCC-ee machine induced backgrounds on the two proposed detectors (CLD and IDEA) have been studied in detail. Synchrotron Radiation (SR) considerations dictate the Interaction Region (IR) optimization. An asymmetric IR design limits the final bend critical energy to 100 keV. Masks placed before the final focus quadrupole protect the detector from direct hits, and a shield placed around the beam pipe from secondary particles, keeping the effect of SR on the detector to negligible levels. The most important source of background is expected to be the Incoherent Pair Creation (IPC). Its effect has been studied in full simulation and reconstruction, and it was shown that it will not pose a problem for the detector, even if conservative estimations for the time resolution of the detector sensors are assumed. Moreover, the [Formula: see text], radiative Bhabhas and beam-gas interaction induced backgrounds were studied. All were found to have small to negligible effect on the detector. Overall, the FCC–ee interaction region backgrounds are not expected to compromise the detector performance.

IR challenges and the machine detector interface at FCC-ee

“…An efficient SR masking and shielding design used to protect the detectors and produce a sustainable maximum occupancy have been studied and described in the CDR (see also Refs. [12][13][14]). The possible sources of background from SR come from the last bending magnet from the IP.…”

Challenges for the interaction region design of the Future Circular Collider FCC-ee

“…An efficient SR masking and shielding design used to protect the detectors and produce a sustainable maximum occupancy has been studied and described in the CDR (see also Refs. [8][9][10][11]). The SR background has also been initially studied for the smaller central chamber, where it is shown how to modify the SR masks to the new design [12].…”