Radio Frequency attenuation of thin aluminized plastic filters investigated for the ATHENA X-IFU detector

Athena will be an X-ray space observatory addressing the Cosmic Vision programme theme "Hot and Energetic Universe". Its aim is to provide both spatially resolved ultra high-resolution spectroscopy, through the X-ray Integral Field Unit (X-IFU) instrument, and wide field spectral imaging, through the Wide Field Imager (WFI) instrument. The X-IFU will employ highly sensitive transition edge sensors (TES) operating at 50 mK. The thermal shields (Fig. 1) of its cryostat will have windows, consisting in thin filters (Fig. 2), allowing the X-rays to cross through while rejecting the unwanted radiation.