Test-beam characterisation of the CLICTD technology demonstrator - a small collection electrode High-Resistivity CMOS pixel sensor with simultaneous time and energy measurement

TL;DR

This paper reports on the beam test characterization of the CLICTD monolithic CMOS pixel sensor, demonstrating high spatial and temporal resolution, high efficiency, and potential for particle tracking in collider experiments.

Contribution

It introduces a novel CMOS pixel sensor with simultaneous time and energy measurement, showing promising performance metrics for high-energy physics tracking detectors.

Findings

Time resolution of 5.8 ns achieved

Spatial resolution of 4.6 microns achieved

Hit detection efficiency exceeds 99.7%

Abstract

The CLIC Tracker Detector (CLICTD) is a monolithic pixel sensor. It is fabricated in a 180 nm CMOS imaging process, modified with an additional deep low-dose n-type implant to obtain full lateral depletion. The sensor features a small collection diode, which is essential for achieving a low input capacitance. The CLICTD sensor was designed as a technology demonstrator in the context of the tracking detector studies for the Compact Linear Collider (CLIC). Its design characteristics are of broad interest beyond CLIC, for HL-LHC tracking detector upgrades. It is produced in two different pixel flavours: one with a continuous deep n-type implant, and one with a segmented n-type implant to ensure fast charge collection. The pixel matrix consists of $16\times128$ detection channels measuring $300 \times 30$ microns. Each detection channel is segmented into eight sub-pixels to reduce the amount of digital circuity while maintaining a small collection electrode pitch. This paper presents the characterisation results of the CLICTD sendor in a particle beam. The different pixel flavours are compared in detail by using the simultaneous time-over-threshold and time-of-arrival measurement functionalities. Most notably, a time resolution down to $(5.8 \pm 0.1)$ ns and a spatial resolution down to $(4.6 \pm 0.2)$ microns are measured. The hit detection efficiency is found to be well above 99.7% for thresholds of the order of several hundred electrons.