Euclid preparation: LXXX. Overview of Euclid infrared detector performance from ground tests

Abstract

This paper describes the objectives, design, and findings of the pre-launch ground characterisation campaigns of the Euclid infrared detectors. The aim of the ground characterisations is to evaluate the performance of the detectors, to calibrate the pixel response, and to derive the pixel response correction methods. The detectors have been tested and characterised in the facilities set up for this purpose. The pixel properties, including baseline, bad pixels, quantum efficiency, inter pixel capacitance, quantum efficiency, dark current, readout noise, conversion gain, response non-linearity, and image persistence were measured and characterised for each pixel. We describe in detail the test flow definition that allows us to derive the pixel properties and we present the data acquisition and data quality check software implemented for this purpose. We also outline the measurement protocols of all the pixel properties presented and we provide a comprehensive overview of the performance of the Euclid infrared detectors as derived after tuning the operating parameters of the detectors. The main conclusion of this work is that the performance of the infrared detectors Euclid meets the requirements. Pixels classified as non-functioning accounted for less than 0.2% of all science pixels. The interpixel capacitance (IPC) coupling is minimal, the cross-talk between adjacent pixels is less than 1% between adjacent pixels, and 95% of the pixels show a quantum efficienty (QE) greater than 80% across the entire spectral range of the Euclid mission. The conversion gain is approximately 0.52 ADU/e-, with a variation of less than 1% between channels of the same detector. The reset noise is approximately equal to 23 ADU rms after reference pixel correction. The readout noise of a single frame is approximately 13 e- rms while the signal estimator noise is measured at 7 e- rms in photometric mode and 9 e- rms in spectroscopic acquisition mode. The deviation from linear response at signal levels up to 80 ke- is less than 5% for 95% of the pixels. Median persistence amplitudes are less than 0.3% of the signal, though persistence exhibits significant spatial variation and differences between detectors.