[Ifeffit] programming error in Hephaestus??

I.Reitz I.Reitz at dkfz-heidelberg.de
Fri Jun 1 03:10:51 CDT 2007


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 at dkfz.de

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