Design, performance and future prospects of vertex detectors at the FCC-ee

TL;DR

This paper reviews the design, current status, and future improvements of vertex detectors at the FCC-ee collider, emphasizing low material budgets and enhanced vertexing for heavy flavor physics.

Contribution

It presents the latest engineered vertex detector designs, integration strategies, simulation results, and introduces a novel ultra-light detector concept using curved wafer-scale MAPS.

Findings

Vertex detectors achieve ~3 μm resolution with 0.3% radiation length material budget.

Simulation indicates predicted high performance for physics measurements.

A new ultra-light detector concept reduces material by nearly three times, enhancing heavy flavor decay detection.

Abstract

The CERN proposed $e^+e^-$ Future Circular Collider (FCC-ee) is an electroweak, flavour, Higgs and top factory with unprecedented luminosities. Many measurements at the FCC-ee will rely on precisely determining the particle production vertices using dedicated vertex detectors. All vertex detector designs use Monolithic Active Pixel Sensors (MAPS) with a single-hit resolution of $\approx$ 3 $\mu$m and a material budget as low as 0.3% of a radiation length per detection layer, which is within specifications for most of the physics analyses. This contribution presents the status of the fully engineered vertex detectors and their integration with the collider beam pipe and discusses their predicted performance using the DD4hep full simulation. A concept for an ultra-light vertex detector using curved wafer-scale MAPS is also presented, which allows reducing the material budget by almost a factor of three. This improves the vertexing capabilities, especially for heavy flavour decays, such as $B^0 \rightarrow K^{*0} \tau^+ \tau^-$.