FACET: A new long-lived particle detector in the very forward region of the CMS experiment

TL;DR

FACET is a proposed detector extension for the CMS experiment designed to detect long-lived particles in the very forward region, enhancing the search for beyond standard model physics at the LHC.

Contribution

This paper introduces FACET, a novel detector subsystem for CMS, specifically targeting long-lived particles in the high-luminosity LHC era.

Findings

Design of FACET detector with 50 m penetration capability

Sensitivity to various long-lived particles like dark photons and axion-like particles

Integration with CMS Phase-2 upgrade technology

Abstract

We describe a proposal to add a set of very forward detectors to the CMS experiment for the high-luminosity era of the Large Hadron Collider to search for beyond the standard model long-lived particles, such as dark photons, heavy neutral leptons, axion-like particles, and dark Higgs bosons. The proposed subsystem is called FACET for Forward-Aperture CMS ExTension, and will be sensitive to any particles that can penetrate at least 50 m of magnetized iron and decay in an 18 m long, 1 m diameter vacuum pipe. The decay products will be measured in detectors using identical technology to the planned CMS Phase-2 upgrade.