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Question structure of GEANT4 data files (cold neutrons on LH2 target) 

Forum: Hadronic Processes
Date: 16 Dec, 2011
From: Emil Frlez <Emil Frlez>

 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

geant4.9.4/data/G4NDL3.14/Elastic/CrossSection/1_1_Hydrogen

 (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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1 None: Re: structure of GEANT4 data files (cold neutrons on LH2 target)   (Koi, Tatsumi - 16 Dec, 2011)
(_ Question: Re: structure of GEANT4 data files (cold neutrons on LH2 target)   (Cristian Bungau - 03 Dec, 2013)
(_ None: Re: structure of GEANT4 data files (cold neutrons on LH2 target)   (michel maire - 04 Dec, 2013)
(_ More: Re: structure of GEANT4 data files (cold neutrons on LH2 target)   (Cristian Bungau - 04 Dec, 2013)
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