# Efficient Charge Collection in Coplanar Grid Radiation Detectors

## TL;DR

This paper models and simulates laser-induced transient currents in coplanar grid radiation detectors, demonstrating improved spectral resolution and analyzing factors affecting detector performance.

## Contribution

It introduces a comprehensive numerical model combining finite element analysis and Monte Carlo simulations to optimize coplanar grid detector design.

## Key findings

- 10× improved spectral resolution using differential signal sensing
- Space charge and non-uniform electric fields significantly affect transient current waveforms
- Model successfully matches experimental data and suggests design simplifications

## Abstract

We have modeled laser-induced transient current waveforms in radiation coplanar grid detectors. Poisson's equation has been solved by finite element method and currents induced by photo-generated charge were obtained using Shockley-Ramo theorem. The spectral response on a radiation flux has been modeled by Monte-Carlo simulations. We show 10$\times$ improved spectral resolution of coplanar grid detector using differential signal sensing. We model the current waveform dependence on doping, depletion width, diffusion and detector shielding and their mutual dependence is discussed in terms of detector optimization. The numerical simulations are successfully compared to experimental data and further model simplifications are proposed. The space charge below electrodes and a non-homogeneous electric field on a coplanar grid anode are found to be the dominant contributions to laser-induced transient current waveforms.