4D Tracking: Present Status and Perspective

Abstract

The past ten years have seen the advent of silicon-based precise timing detectors for charged particle tracking. The underlying reason for this evolution is a design innovation: the Low-Gain Avalanche Diode (LGAD). In its simplicity, the LGAD design is an obvious step with momentous consequences: low gain leads to large signals maintaining sensors stability and low noise, allowing sensor segmentation. Albeit introduced for a different reason, to compensate for charge trapping in irradiated silicon sensors, LGAD found fertile ground in the design of silicon-based timing detectors. Spurred by this design innovation, solid-statebased timing detectors for charged particles are going through an intense phase of R&D, and hybrid and monolithic sensors, with or without internal gain, are being explored. This contribution offers a review of this booming field.

Testbeam results of irradiated SiGe BiCMOS monolithic silicon pixel detector without internal gain layer

“…The particle-physics community is presently attempting to develop a new generation of silicon sensors able to achieve both high spatial granularity and excellent timing capabilities [4,5], although the radiation tolerance of the gain layer still constitutes a problem to place these sensors at small radii in present and future high-energy hadron colliders, where radiation will be very high. Studies to overcome the limited radiation tolerance of the gain layer are ongoing [6][7][8].…”