Preparation of the Euclid space mission: study of the correlations, at the pixel level, of the infrared detectors’ response

Stage numéro : Doctorat-2124-RE-03
Laboratoire :Centre de Physique des Particules de Marseille Case 902
 163 avenue de Luminy - 13288 Marseille Cedex 9
Directeur :Cristinel Diaconu - 04.91.82.72.01 - diaconu@cppm.in2p3.fr
Correspondant :William Gillard - 04.91.82.72.67 - gillard@cppm.in2p3.fr
Groupe d'accueil :Renoir
Chef de groupe :Dominique Fouchez - 04.91.82.72.49 - fouchez@cppm.in2p3.fr
Directeur de thèse :Aurélia Secroun - Eric Kajfasz - 0491827215 - secroun@cppm.in2p3.fr

Thématique : Instrumentation

Euclid is an M-class ESA mission due to launch in 2022. It is one of the major observatories dedicated to cosmology and understanding the nature of Dark Energy through the mapping of all visible and infrared sky. The NISP (near-infrared spectrophotometer) instrument aboard Euclid holds the largest infrared focal plane array to fly and is filled with 16 infrared detectors specially designed and fabricated for Euclid by the American company Teledyne, and selected among 60 detectors by NASA as the highest performing detectors.

Those ‘H2RG’ detectors are constituted by a mosaic of 4 million hybrid HgCdTe pixels and make for a major contribution to the acquisition chain with a rather intricate behavior, as already observed during tests. Being able to precisely describe their behavior and extract parameters such as readout noise, conversion gain, or linearity, at the pixel level is an important challenge for reaching a sufficient processing quality and for meeting the 1% accuracy requirement on the final data.

The objective of the thesis is thus to derive a ‘pixel’ analysis of the detector response through a global approach of the various performance parameters (namely, noise, linearity, latency, etc.). This analysis will be based on the on-ground calibration of the flight detectors performed by CPPM in preparation of the Euclid mission with a view to providing reference maps at the pixel level for the correction and data processing of flight data. Two series of data are available (with some 1Po recorded on disk): a first series corresponds to the characterization of detectors carried out on dedicated test benches installed at CPPM, a second series corresponds to tests implemented during the full instrument calibration at LAM with slightly different experimental conditions.


- The pixel analysis will allow to bring out spatial variations and should lead to individual pixel performance.


- A thorough study will require looking further into the finest effects that have been revealed during the tests, and propose original methods to derive the various parameters considering their observed intertwining.


- It should also look into the correlations between pixels, the acquisition history and the experimental specificities.

The PhD student will be a member of the Euclid Consortium, with full access to Euclid data.

Keywords: Instrumentation, Detector, Infrared, Calibration, Spectrometry, Photometry, EUCLID, Data analysis

Applicant profile: The candidate should hold a Master of Sciences or Master of Engineering in instrumentation for space sciences or similar specialty. Good programming skills (python), good knowledge in signal processing and bases in instrumentation and semi-conductor physics are required. Strong motivation and ability to work in team are definitely appreciated.