This is the home page of the X-ray Integral Field Unit (X-IFU) proposed for the Athena X-ray Observatory; the second large mission of the European Space Agency science program, to be launched in 2028. The Athena mission is designed to implement the Hot and Energetic Universe science theme.

The X-IFU is a cryogenic X-ray spectrometer, based on a large array of Transition Edge Sensors (TES), offering 2.5 eV spectral resolution, with 5’’ pixels, over a field of view of 5 arc minutes in equivalent diameter.