Preliminary design and simulation for CEPC fast luminosity monitor detector based on 4H-SiC

TL;DR

This paper presents a simulation-based design of a 4H-SiC fast luminosity detector for CEPC, enabling precise real-time luminosity monitoring to improve beam stability in high-luminosity collider operations.

Contribution

It introduces an optimized 4H-SiC detector scheme with picosecond resolution and a software tool for design optimization, advancing luminosity measurement techniques for CEPC.

Findings

Achieved 2% relative precision at 1 kHz sampling rate.

Established linear correlation between Total Sample Current and luminosity.

Demonstrated potential for real-time luminosity monitoring.

Abstract

The Circular Electron-Positron Collider (CEPC), a next-generation high-luminosity collider, employs a crab waist scheme to achieve ultrahigh $5 \times 10^{34} \, \text{cm}^{-2}\text{s}^{-1}$ luminosity at Higgs mode. Owing to the extremely small beam size, the luminosity is highly sensitive to the stability of final focusing elements, where mechanical vibrations (e.g. ground motion) may induce beam offsets and luminosity degradation. To address this, a luminosity-driven dithering system is implemented for horizontal beam stabilization. In this work, we develop an optimized 4H-SiC fast luminosity detector scheme using an array of radiation detectors with picosecond time resolution positioned at critical locations. By using self-development software RAdiation SEmiconductoR (RASER), we optimize the active area of the detector to achieve 2\% relative precision at 1~kHz. Furthermore, the Total Sample Current (TSC) exhibits a near-linear correlation with luminosity attenuation, enabling real-time luminosity monitoring.