Defocussing of the Athena optics is now a requirement and can be considered in evaluating the count rate performance of the X-IFU. Defocussing spreads the source counts over a large number of pixels (1000). Each pixel can sustain a count rate of the order of 40-50 cps. A Crab like source would produce about 90 000 cps over the full TES array. Therefore it is obvious that with defocussing, the X-IFU is capable of observing bright point sources. [caption id="attachment_770" align="aligncenter" width="300"] Broad band (0.2-12 keV) high resolution and total throughputs[/caption] High throughput for mid and high resolution events (spectral resolution less than 10 eV) is certainly required around the Iron like between 5 and 8 keV. The use of Be filters would remove a large fraction of the soft photons and therefore reduce the overall count rate of point sources while preserving the interesting events above 5 keV. The X-IFU can achieve throughputs as high as 70% with maximum defocussing and the use of Be filter. The above number will reduce (by a few 10% at 1 Crab) if events affected by cross talk are removed. [caption id="attachment_771" align="aligncenter" width="300"] The high+mid resolution event fraction in the 5-8 keV band.[/caption] The figures shown above are courtesy of Philippe Peille (December 2016), on behalf of the end-to-end simulator team.
Thanks to Françoise Douchin, on behalf of the editorial team, I am please to announce the release of the January 2017 issue of the X-IFU Gazette. Enjoy the reading. Don't hesitate to provide feedback to Françoise on the content of the X-IFU Gazette. Best regards, Françoise and Didier
On behalf of the X-IFU consortium, we would like to wish you a happy, healthy and peaceful New Year.We are clearly living through difficult times, so developing education, promoting culture and improving human knowledge should remain priorities for those intending to make our Earth a better place to live in. This is why your contribution to the development of the X-IFU is also important, as it will eventually lead to breakthroughs in our understanding of the whole Universe. All the best and best regards,Didier and Thien