This paper details the development of the Adiabatic Demagnetization Refrigerator (ADR) control electronics for X-IFU instrument, of ESA’s newAthena observatory. The ADR operates in a closed loop using a PID system, where the voltage bias is regulated based on the temperature measurements. The core of this work details the design and development of two electronics board prototypes, a differential low noise amplifier and a power supply board, addressing the unique space constraints and operational requirements. The ultra-low noise amplifier is designed to readout a 50mK resistive sensor. We have achieved a noise level of 2nV/√Hz which is critical for addressing the challenges of thermal stability (0.8μK RMS at 50mK), essential to achieve the instrument’s target resolution of 2.5eV. Preliminary results of the ADR cooler’s performance and its control electronics will be presented, emphasizing the temperature regulation achievements during the observation phase.
The goal of the SPID/IQSENS project is the development of SNSPD for specific applications, requiring wavelength sensitivity longer than the communication window of 1550 nm. In this paper, the status of the research and development of SNSPD within the SPID/IQSENS is presented.
Absolute Quantum Efficiency (QE) measurements are very demanding. To measure the QE of detectors from 0.8μm to 12.5μm a dedicated test bench has been built. The Quantix test bench relies on an optical design ensuring a uniform flat-field illumination of the detector. The illumination uniformity was measured with photodiodes built and calibrated at CEA/LETI. While performing QE measurements, the calibrated photodiode is placed in the vicinity of the detector to measure the incident flux. The Quantix test bench has been validated with a detector whose QE has been measured at the European Space Agency. In this paper, the test bench will be described in details and QE measurements performed on near infrared, MCT-based detectors will be presented. The intra-pixel response is also an important parameter to know as it can affect the accuracy of photometric and shape measurements. The Intrapix test bench has been specifically designed for this measurement, using the Talbot effect to simultaneously measure the intra-pixel response in a large number of subareas of a given detector, from 0.5 μm to 12 μm. The paper will give a brief status of the test bench development.
The program Astronomy European Infrared Detector (ASTEROID), funded by the European Union through H2020 (under Grant Agreement n°730161), aims at enabling Europe to acquire the technology and knowledge necessary to manufacture 2k² high performance IR detectors. To reach these goals 9 detectors have been manufactured at Lynred and characterized at the Astrophysics Department of CEA. ASTEROID detectors are 640×512 pixels arrays with a pixel pitch of 15 μm. The detectors are p-on-n technology, with 15 μm pixel pitch, with a cut-off wavelength of 2.1 μm. In the detector architecture, the MCT light-sensitive layer is hybridized on a Source Follower Detector (SFD) Read Out Integrated Circuit (ROIC) via indium bumps. In this paper, the characterization results of ASTEROID detectors will be presented. The best detectors show extremely low dark current around 0.001 e-/s/pix, which is equivalent to standard H2RG IR detector (widely used in the IR domain for astrophysics applications). The quantum efficiency (QE) of these detectors has also been measured on a dedicated test bench and will be presented. ASTEROID detectors demonstrated a QE of 70 %.
The Athena observatory is the second large class ESA mission to be launched in early 2030's. One of its two instruments on board is the X-ray Integral Field Unit (X-IFU). X-IFU will provide a high energy resolution of 2.5eV at 7keV thanks to cryogenic micro-calorimeter of Transition Edge Sensor (TES). In this paper, we will describe the architecture of the ADR control electronics designed following space constraint rules. In particular, two prototypes have been developed. The first one is a differential low noise amplifier with an equivalent input noise density close to 2nV/√Hz at 1kHz. Together with ruthenium oxide thermometer from Lakeshore are dedicated to 50mK measurement. A goal of a noise below 0.4μK/√(Hz) RMS, twice thermal stability requirement is targeted. The second board uses DC/DC converter followed by a fully integrated low dropout voltage regulator (LDO) to supply the ADR superconducting coil. It will control precisely the voltage applied to the ADR cooler during regulation phase and provide up to 2A current during the recycling phase. Complementary approach regarding ADR regulation using simulation with a simplified model of the ADR in Matlab-Simulink will be presented herein.
We 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.
In this paper, we present our developments on micro-calorimeter arrays, based on High Impedance Silicon sensors (MIS or resistive TES) micro-calorimeters and GaAS-GaAlAs HEMTs / SiGe cryo-electronics, started 5 years ago. We show the pixel design, the main steps to build a 32x32 array. We are presently developing two kinds of high impedance sensors: Metal-Insulator-Sensors and High Resistivity Transition Edge Sensors. We described our associated FrontEnd electronics and detailed system level analysis of the foreseen camera. We discuss why we will be able to handle a camera with a large number of pixels (thanks to excellent thermal insulation and no electronic power consuming at the 50mK stage). We discuss the main technological building blocks (Absorber, Sensor) and their present status.
Bolometers cooled to very low temperature are currently the most sensitive detectors for low spectral resolution
detection of millimetre and sub-millimetre wavelengths. The best performances of the state-of-the-art bolometers allow
to reach sensitivities below the photon noise of the Cosmic Microwave Background for example. Since 2003, a french
R&D effort called DCMB ("Developpement Concerte de Matrices de Bolometres") has been organised between different
laboratories to develop large bolometers arrays for astrophysics observations. Funded by CNES and CNRS, it is intended
to get a coherent set of competences and equipments to develop very cold bolometers arrays by microfabrication. Two
parallel developments have been made in this collaboration based on the NbSi alloy either semi-conductive or
superconducting depending on the proportion of Nb. Multiplexing schemes have been developed and demonstrated for
these two options. I will present the latest developments made in the DCMB collaboration and future prospects.
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