|Message: structure of GEANT4 data files (cold neutrons on LH2 target)||Not Logged In (login)|
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Hi - I am trying to understand the structure of GEANT4 data files. Is there any documentation on that?
For example, to make it concrete, I am interested in
(I am studying a few meV neutrons on liquid Hyrdogen target.) The first 59 lines of that file looks like this (the whole file has 168 lines):
2 0 167 .100000E-04 0.2048E+02 .253000E-01 0.2048E+02 .100000E+03 0.2046E+02 .316228E+03 0.2040E+02 .100000E+04 0.2034E+02 .149535E+04 0.2021E+02 .273436E+04 0.2002E+02 .500000E+04 0.1983E+02 .707107E+04 0.1952E+02 .. .. .980000E+08 0.7653E-01 .100000E+09 0.7493E-01
I cannot find anywhere the meaning of first 3 lines: 2, 0, 167. Next, it appears that six column lines give the energy (in eV) and the cross section (in barn)?
Then, the whole patern of the top 59 lines repeats itself 3 more times. So, I surmise that "167" is the number of data lines? (Last line is an empty line.)
I need to understand this structure because I would like to change this data file. I would like to have cross section file for a particular mixture of para- and ortho-hydrogen. If I am interested just in neutrons in 1-100 meV range, should I just replace a few top lines in all 3 sections? Can I add finer sampling of cross sections in energy (increase the number of data lines in the data file)?
The next question: how does the GEANT4 cross section depend on temperature and pressure of material?
For example, I set my target material to be new G4Material("H2Liq" , z= 1, a= 1.01*g/mole, density= 70.8*mg/cm3, kStateLiquid, temperature=20*kelvin, pressure=1.5*atmosphere);
Will changing the temperature and pressure change the cross sections GEANT4 uses? I have tried to study the source code, but the coding was confusing given my (limited ;8-) C++ abilities ... Is there a GEANT4 Class I can use the print/query about the cross sections used as I set a particular material at the particular temperature and pressure?
Thanks in advance, Emil
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