The focal plane assembly for the ATHENA x-ray integral field unit instrument (Conference Presentation)

The X-ray Integral Field Unit (X-IFU) is an imaging microcalorimeter being developed for ESA's Athena X-ray observatory to providing high spectral resolution imaging between 0.2-12 keV, with moderate count-rate capability and a large field-of-view. The X-IFU focal plane assembly (FPA) will contain the instrument's large-format transition edge sensor (TES) microcalorimeter array and its superconducting readout electronics, plus a second TES detector, located behind the main sensor array, is used to detect high-energy cosmic rays and secondary particles passing through the sensor array and enable the rejection of false events that they generate in the sensor array's event list. A Kevlar thermal suspension is used to isolate the detectors at 55 mK from the 2 K environment of the X-IFU instrument cryostat's cold stage, while three layers of shielding are used to allow the detector's to achieve their low-noise performance in the expected on-ground and in-flight electromagnetic and microvibration environment. This paper will describe the preliminary design concept of the X-IFU focal plane assembly and its critical technology building blocks.