Improving the Spatial Resolution of Silicon Pixel Detectors through Sub-pixel Cross-coupling

TL;DR

This paper proposes a sub-pixel cross-coupling method to enhance the spatial resolution of silicon pixel detectors by enabling directional charge sharing, achieving up to 30% improvement in resolution.

Contribution

The paper introduces a novel sub-pixel coupling scheme for silicon pixel detectors, evaluated through simulations to improve spatial resolution by up to 30%.

Findings

Up to 30% improvement in spatial resolution achieved.

Coupling strength influences charge collection efficiency.

Simulation results validate the effectiveness of the proposed method.

Abstract

We present a concept to improve the spatial resolution of silicon pixel-detectors via the implementation of a sub-pixel cross-coupling, which introduces directional charge sharing between pixels. The charge-collection electrode is segmented into sub-pixels and each sub-pixel is coupled to the closest sub-pixel of the neighboring pixel. Such coupling schema is evaluated for a model sensor design with $50 \mu m \times 50 \mu m$ pixels and AC-coupled sub-pixels. A first-order SPICE simulation is used, to determine feasible coupling strengths and assess the influence on the charge-collection efficiency. The impact of the coupling strength on spatial resolution is studied with a dedicated simulation, taking into account charge-cloud evolution, energy-loss straggling, electronic noise, and the charge detection-threshold. Using simplifying assumptions, such as perpendicular tracks and no gaps between charge-collection electrodes, an improvement of the spatial resolution by up to approximately $30\%$ is obtained in comparison to the standard planar pixel layout.