This folder contains the X-IFU throughput and branched ratios for two different configurations:
- Mission as proposed (2 m^2 at 1 keV effective area): throughput_as_proposed.csv
- CDF version (1.4 m^2 at 1 keV effective area): throuput_CDF.csv
Illustration figures showing the available data are also provided.

Each csv file contains 4 semicolon separated columns:
- Count_rate[mCrab]: incoming flux at the entrance of the Athena telescope in units of mCrab
- high_res_ratio: ratio of high resolution events (nominal 2.5 eV FWHM energy resolution)
- degraded_ratio: ratio of events with degraded energy resolution (taken at a guess value of 10 eV for the purpose of the CDF vs. as proposed assessment exercise)
- pileup_ratio: ratio of pileup events, i.e. events which result from two or more photons hitting the same pixel within the same time bin, and which have an energy equal to the sum of the individual photons energies.
- throughput: sum of the three above ratios, i.e. this is the ratio between the number of detected valid events and the number of photons hitting the sensor array (the throughput decreases below 1 at high count rate because the TES reaches saturation). The throughput assumes a TES fall time of 300 microseconds. 


!!!!!!!! CAVEATS !!!!!!!!

These files were obtained through end-to-end simulations using a linear approximation for the TES behavior. These are rough estimates of the future X-IFU count rate performance and are subject to change in the near future. Emphasis is also put on the fact that the energy resolution degradation proposed here does not account for the true continuous degradation that will occur in the instrument.
For all these reasons, these files are not to be used outside of the Athena Science Impact Exercise.


!!!!!!!!!!!!!!!!!!!!!!!!!

A simple example: You wish to simulate a source spectrum having the Crab spectrum but with an intensity of 100 mCrab, and consider only high-resolution events. The Crab spectrum has a norm of 9.5 photons/s/cm2/keV at 1 keV (Nh=0.4e22 cm-2, modeled with TBABS), and the photon index of 2.1

Step 1: Look at the high-res ratio in the csv files for the as proposed configurations: 0.068204
Step 2: Normalize your model with the high res ratio:  0.068204 * 9.5 * 0.1  
Step 3: Fake your spectrum (using the response file for the high resolution events, available from the X-IFU web site)
Step 4: Look at the degraded-res ratio in the csv files for the as proposed configurations: 0.91165
Step 5: Normalize your model with the degraded-res ratio:  0.91165 * 9.5 * 0.1   
Step 6: Fake your spectrum (using the response file for the degraded resolution events, available from the X-IFU web site)

Redo the same for the CDF version and compare the results.

RMF and ARF files for the high-res are available from here: http://x-ifu.irap.omp.eu/spip.php?article23

In this folder, you find RMF for the degraded-res and the throughput files are available from here: http://x-ifu-resources.irap.omp.eu/PUBLIC/RESPONSES/THROUGHPUT/ (use the ARF files from http://x-ifu.irap.omp.eu/spip.php?article23)

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Further enquiries can be addressed to Philippe Peille (ppeille@irap.omp.eu) and Didier Barret (dbarret@irap.omp.eu).