Comparing simulations and test data of a radiation damaged charge-couple device for the Euclid mission

TL;DR

This paper presents a Monte Carlo simulation model for radiation damage in CCDs used in the Euclid mission, enabling comparison with test data to better understand trap properties affecting weak-lensing measurements.

Contribution

The paper introduces a detailed, device-specific Monte Carlo model for radiation damage in CCDs, incorporating physical trap properties and electron density simulations for improved accuracy.

Findings

Model accurately reproduces test data trends

Enhanced understanding of trap positions and properties

Supports correction of radiation damage effects in CCDs

Abstract

The VIS instrument on board the Euclid mission is a weak-lensing experiment that depends on very precise shape measurements of distant galaxies obtained by a large CCD array. Due to the harsh radiative environment outside the Earth's atmosphere, it is anticipated that the CCDs over the mission lifetime will be degraded to an extent that these measurements will only be possible through the correction of radiation damage effects. We have therefore created a Monte Carlo model that simulates the physical processes taking place when transferring signal through a radiation-damaged CCD. The software is based on Shockley-Read-Hall theory, and is made to mimic the physical properties in the CCD as closely as possible. The code runs on a single electrode level and takes three dimensional trap position, potential structure of the pixel, and multi-level clocking into account. A key element of the model is that it also takes device specific simulations of electron density as a direct input, thereby avoiding to make any analytical assumptions about the size and density of the charge cloud. This paper illustrates how test data and simulated data can be compared in order to further our understanding of the positions and properties of the individual radiation-induced traps.