Dear listmembers, I´m a student at the very beginning with synchrotron radiation and we use Hephaestus to calculate the flux through an ionisation chamber. I have some questions (sorry about my bad english): To make it short, I think I have found an error in the tool. In the tool "formulas" I took Kr, 30000 eV and get: the Absorbtion length: 15.031 cm (Resources Henke) : 14.431 cm (Resources Elam) which I also found in NIST Database then use the tool "Ion Chamber" put in Kr (only one gas), 10cm pathlength, 760 Torr, 30000 eV I got for Percentage absorbed: 48.58% (Resources Henke) which is correct I think : 39.22% (Resources Elam) which is wrong I think In my eyes the correct result for 14.431 cm Absorbtion length has to be: 49.99% absorbed photons. It is critical for me, since the correct flux measured with the ionisation chamber goes directly in my results. We investigated the detector response on monochromatic X-rays at HASYLAB of a widely used flat-panel detector in medicine. And I have also a question to you: Why do you use 30 eV/e- as ionization energy for the gases? Is there a reference for that? In addition, don´t we have to take the room temperature into account not only the pressure, that means: Density(Temperature) = (273,15K/293,15K)*0.003749g/cm^3(at 273,15K) Any help and hint is highly appreciated since I am a student at the very beginning. Thanks a lot and warm greetings from Germany Irmi Reitz -- ********************************************* I. Reitz German Cancer Research Center DKFZ, E0401 Dept. of Medical Physics in Radiation Therapy Im Neuenheimer Feld 280 D – 69120 Heidelberg Phone: +49 - 6221 42-2455 Fax: +49 - 6221 42-2572 Email: I.Reitz@dkfz.de *********************************************