Lecture bolométrique à haute sensibilité pour la cosmologie observationnelle et l'exploration de l'univers lointain

Après le succès des missions spatiales infrarouge de l'ESA Planck et Herschel (2009), le développement des détecteurs submillimétriques pixellisés en matrices de plusieurs milliers d'éléments ayant une très haute sensibilité est l'un des grands défis auxquels nous devons apporter des solutions pour répondre aux be- soins des missions scientifiques de l'astrophysique spatiale du futur comme SPICA (JAXA/ESA lancement 2020) ou COrE (ESA lancement > 2025). Dans le cadre du programme " Cosmic Vision " de l'ESA, l'instrument SAFARI a été sélectionné pour une phase de pré-étude qui a débuté avec ce travail de thèse en 2007. SAFARI est un instrument européen pour le futur télescope spatial japonais SPICA dédié à l'observation dans le domaine infrarouge et submillimétrique. L'IRAP développe l'électronique de lecture des matrices de détecteurs de type supraconducteurs pour SAFARI. Le travail que j'ai réalisé dans le cadre de cette thèse concerne la chaîne de lecture en multiplexage fréquentiel d'une matrice de bolomètres supraconducteurs Transi- tion Edge Sensor (TES). Dans ce système, plusieurs détecteurs sont alimentés et lus avec la même paire de fils électrique, chacun étant associé à un résonateur qui lui est spécifique et qui le couple à la composante fréquentielle qui lui est propre. Ce travail s'est développé sur deux axes complémentaires. Un premier axe a consisté à dimensionner et fabriquer une maquette pour un sys- tème de lecture numérique spatialisable. J'ai défini et validé la totalité de la chaîne de lecture de l'instrument SAFARI en partant de la partie froide (détecteurs TES et amplificateur SQUID) jusqu'à l'électronique chaude de lecture (traitement numé- rique du signal). Après des tests de co-simulation analogique-numérique, les algo- rithmes numériques ont été implémentés sur une carte FPGA bas bruit et validés avec un simulateur de SQUID analogique qui fonctionne à température ambiante. Le deuxième axe du travail concerne la mise en place d'un banc de test démons- trateur de SAFARI à l'université de Cardiff. J'ai participé au dimensionnement de la chaîne de mesure complète qui comprend d'une part l'interfaçage TES, SQUID, Ampli bas bruit et l'électronique de lecture, et d'autre part la gestion du logiciel de polarisation, de mesure et d'acquisition des données. Le fruit de cette collaboration (toujours en cours depuis environ un an) a permis de caractériser électriquement et optiquement les bolomètres TES prototypes avec le système que j'ai développé. Après calibration, nous avons mesuré une sensibilité de 2 × 10-18 W racine de Hertz que ce soit en utilisant notre électronique avec multiplexage fréquentiel ou une lecture directe. Cette sensibilité présente un gain d'un facteur 10 à 100 par rapport à la sensibilité des bolomètres utilisés actuellement, par exemple à bord des instruments des missions Herschel ou Planck. Les calculs et les premiers tests faits par ailleurs par nos collaborateurs à Cambridge, Cardiff et SRON montrent que l'objectif de 2 - 3 × 10-19 W racine de Hertz est atteignable. Les détecteurs TES et leurs électronique de lecture et d'asservissement multiplexée en fréquence ont donc été sélectionnés comme chaîne de détection pour l'instrument SAFARI à bord de SPICA lors de la revue de sélection des détecteurs qui s'est tenue vi au SRON à Groningen en Juin 2010 et qui mettait en compétition les systèmes de détecteurs proposés par quatre équipes différentes.We present the design and performance of a digital circuit developed for frequency domain multiplexed (FDM) readout of arrays of high sensitivity su- perconducting Transition Edge Sensors (TES) in the SAFARI spectro-imager on the SPICA infrared telescope. SPICA is a collaborative JAXA-ESA mission due to be launched around 2020. SPICA detectors are organized in 24 readout channels. Each channel consists of up to 160 TES detectors coupled to a single Superconducting Quantum Interference Device (SQUID) amplifier through individual LC filters which determine the AC readout frequency of each detector. The standard procedure to readout a SQUID current amplifier is by using negative feedback, thereby nulling its flux from which it derives its name : flux-locked loop (FLL). This circuit linearizes the sinusoidal SQUID response and enhances its rather limited dynamic range. The gain-bandwidth of a FLL is limited by the cable delay between SQUID amplifier and the warm electronics, which generates output and feedback for the FLL. The long cables on SPICA make a standard FLL unsuitable for for the feedback of signals modulated onto AC-carriers in the 1 - 3 MHz range. In our system, the required high gain at each carrier frequency is achieved by the correction for this delay using a digital Baseband feedback (BBFB) readout which monitors the amplitude of each carrier and synthesizes the correct wave phase to the SQUID feedback coil. The maximum achievable gain-bandwidth for BBFB depends on the spacing between the 160 carriers in each channel and has been designed such that it is sufficient for the rather slow detectors on SAFARI. We have integrated and tested BBFB with prototype of TES detectors and resonators. We have demonstrated a successful operation of BBFB with a single resonator and TES operating in its transition, the noise measurements are consistent with the expectation of 2 × 10-18 W root Hertz. The design has been made such that the sky backgrounds and telescope baffle dominate the sensitivity. The detector NEP requirement is set to 2 - 3 × 10-19 W root Hertz. Till now, the SAFARI TES team, led by the university of Cardiff and SRON have demonstrated a NEP of about 3 × 10-19 W root Hertz. Our readout system demonstrated the performances required to allow its selection for the SAFARI instrument

CAGIRE: a wide-field NIR imager for the COLIBRI 1.3 meter robotic telescope

The use of high energy transients such as Gamma Ray Bursts (GRBs) as probes of the distant universe relies on the close collaboration between space and ground facilities. In this context, the Sino-French mission SVOM has been designed to combine a space and a ground segment and to make the most of their synergy. On the ground, the 1.3 meter robotic telescope COLIBRI, jointly developed by France and Mexico, will quickly point the sources detected by the space hard X-ray imager ECLAIRs, in order to detect and localise their visible/NIR counterpart and alert large telescopes in minutes. COLIBRI is equipped with two visible cameras, called DDRAGO-blue and DDRAGO-red, and an infrared camera, called CAGIRE, designed for the study of high redshift GRBs candidates. Being a low-noise NIR camera mounted at the focus of an alt-azimutal robotic telescope imposes specific requirements on CAGIRE. We describe here the main characteristics of the camera: its optical, mechanical and electronics architecture, the ALFA detector, and the operation of the camera on the telescope. The instrument description is completed by three sections presenting the calibration strategy, an image simulator incorporating known detector effects, and the automatic reduction software for the ramps acquired by the detector. This paper aims at providing an overview of the instrument before its installation on the telescope.Comment: Accepted by Experimental Astronom

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. (abridged).Comment: 48 pages, 29 figures, Accepted for publication in Experimental Astronomy with minor editin

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over a hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. The X-IFU will be provided by an international consortium led by France, The Netherlands and Italy, with ESA member state contributions from Belgium, Czech Republic, Finland, Germany, Poland, Spain, Switzerland, with additional contributions from the United States and Japan.The French contribution to X-IFU is funded by CNES, CNRS and CEA. This work has been also supported by ASI (Italian Space Agency) through the Contract 2019-27-HH.0, and by the ESA (European Space Agency) Core Technology Program (CTP) Contract No. 4000114932/15/NL/BW and the AREMBES - ESA CTP No.4000116655/16/NL/BW. This publication is part of grant RTI2018-096686-B-C21 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. This publication is part of grant RTI2018-096686-B-C21 and PID2020-115325GB-C31 funded by MCIN/AEI/10.13039/501100011033

LWIR quantum efficiency measurements using a calibrated MCT photodiode read by a cryo-HEMT-based amplifier

International audienceWe present a new development for the measurement of the Quantum Efficiency (QE) of a Mercury Cadmium Telluride (HgCdTe or MCT) detector array in the long wave infrared (LWIR) spectral band. To measure the incident photon flux on the detector, CEA-LETI has designed and produced a calibrated MCT photodiode which, under the test setup conditions used for the QE measurement, delivers a total (dark plus photonic) current of 1nA at 60K. The readout of such a low level of current makes a standard room temperature amplifier inconvenient due to the length of the wires between the focal plane (FP) at cold and the outside of the cryostat (>2m in the current cryostat). A much better approach is to use High Electron Mobility Transistors (Cryo-HEMTs), optimized by CNRS/C2N laboratory for ultra-low noise at very low temperatures (<1K). We have developed a Cryo-HEMT-based transimpedance amplifier to readout the photonic current of the calibrated MCT chip. The paper describes the calibrated photodiode, the Cryo-HEMT amplifier and the test setup, and shows the results of the QE measurements of the LWIR detector

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

48 pages, 29 figures, submitted for publication in Experimental AstronomyThe Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. It is expected that thanks to the studies conducted so far on X-IFU, along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained (abridged)

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

48 pages, 29 figures, submitted for publication in Experimental AstronomyThe Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. It is expected that thanks to the studies conducted so far on X-IFU, along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained (abridged)