Wide band transmission response of X-IFU thermal filters

The paper titled “Wide Band Transmission Response of the Filters for the X-IFU Detector of the Athena Observatory”, presented at ICSO 2024, investigates the optical blocking filters used in the X-ray Integral Field Unit (X-IFU) aboard the Athena space observatory. These filters, composed of polyimide films coated with aluminum, are designed to block out-of-band radiation—such as UV, optical, and IR light—while allowing high transmission in the X-ray range (0.2–12 keV). The study evaluates 45 nm thick polyimide filters, either bare or coated with ~30 nm of aluminum, using multiple spectroscopy techniques over a broad spectral range, including X-ray, VUV, NUV-Vis-NIR, and IR. 

Some of the experimental data were collected at leading facilities like BESSY II (Germany) and SOLEIL (France). Results showed that bare polyimide films are transparent in the soft X-ray region but transmit undesirable radiation at other wavelengths, while aluminum-coated filters significantly reduce this out-of-band transmission without compromising X-ray performance. Notably, strong absorption features were observed in the UV and visible range, with absorption edges related to the chemical elements involved in the materials evident between 73 eV and 1560 eV. This work marks the first comprehensive measurement of the full spectral response of the baseline X-IFU filters, providing essential input for filter design, detector calibration, and mission performance optimization. Further investigations are planned in the far-IR region to complete the filter characterization.

Scientific paper

• Wide-band transmission response of the filters for the X-IFU detector of the Athena Observatory, by Todaro M. et al., International Conference on Space Optics, Antibes – Juan les Pins, France, 24-25 octobre 2024. OA Link: http://hdl.handle.net/10447/689553