Cross section table file format


Common file header is as follows:
   !filetype    xs <ia>
   !fileversion <yyyymmdd>
   !filedate    <dow> <mmm> <dd> <hh>:<mm>:<ss> <yyyy> 
   #
   # comment
   #
where <ia> is the type of interaction, see following sections.
The usual file name extension is: .<ia>.xs.

The !fileversion tag specifies a particular format version for the respective cross section. Its purpose is to allow future format extensions and to inform the reader routines that such extensions are to be expected. yyyymmdd specifies an integer representing year, month and day, respectively. For example, the basic format designed in 20080825 might receive an upgrade in 20130131, so all files using the additional features will/should have this new file version.
Nevertheless the regular TRAX readers are able to skip unknown keywords and associated data sections. One or several warning messages will be issued in this case.

The !filedate tag merely gives the file creation date and time, as output by the ctime() function.

Comment lines start with # and can appear anywhere.

Electromagnetic (EM) interactions

EM interactions comprise elastic scattering, excitation, and ionization. Cross sections can be total (TCS), single differential in energy (or angle) (SDCS), and double differential in both energy and angle.
The common cross section file header is followed by:
!target      <material>
where <material> specifies a generic material name or chemical composition. Targets can be atomic or molecular.

Total Cross Sections (TCS)

Interactions <ia>={'l,t' | 'x,t' | 'i,t' } are foreseen for total elastic scattering, excitation, and ionization, respectively.
The common EM interaction file header is followed by:
!projectile   <projectile>
!shell      <shell-number_1>
<E_proj> <sigma_xx/cm**2> [<E_loss>] 
...
!shell      <shell-number_n>
<E_proj> <sigma_xx/cm**2> [<E_loss>] 
Partial cross sections for the different atomic or molecular electronic shells of the target may be given. Use !shell 0 for the sum of all shells.
The projectile energy <E_proj> is given in MeV/u for ionic projectiles and in keV for the others.
The energy loss <E_loss> is the potential energy needed for the respective interaction. It is optional and makes sense for excitations and for the sum of all shells (!shell 0). It is expected in keV.

Single Differential Cross Sections (SDCS)

Ionization

Interaction <ia>={ 'i,s' } is foreseen for single (energy) differential ionization, i.e. secondary electron energy spectra.
The common EM cross section file header is followed by:
!projectile   <projectile>
!shell      <shell-number_1>
!eproj      <E_proj_1> [<E_loss>]  
<E_e-/keV> <dsigma_si/dE/cm**2/keV>  
...
!eproj      <E_proj_2> [<E_loss>]
<E_e-/keV> <dsigma_si/dE/cm**2/keV>  
...
!shell      <shell-number_n>
!eproj      <E_proj_1> [<E_loss>]
<E_e-/keV> <dsigma_si/dE/cm**2/keV>  
... 
Partial cross sections for the different atomic or molecular electronic shells of the target may be given. Use !shell 0 if the sum of all shells is given.
The projectile energy <E_proj> is given in MeV/u for ionic projectiles and in keV for the others.

Elastic Scattering

Interaction <ia>={ 'l,s' } is foreseen for elastic scattering angular distributions.
The common EM cross section file header is followed by:
!projectile   <projectile>
!shell      <shell-number_1>
!eproj      <E_proj_1>
<cos(theta)> <dsigma_sl/dOmega/cm**2/sr>  
...
!eproj      <E_proj_2>
<cos(theta)> <dsigma_sl/dOmega/cm**2/sr>  
...
!shell      <shell-number_n>
!eproj      <E_proj_1>
<cos(theta)> <dsigma_sl/dOmega/cm**2/sr>  
... 
Partial cross sections for the different atomic or molecular electronic shells of the target may be given. Use !shell 0 if the sum of all shells is given.
The projectile energy <E_proj> is given in MeV/u for ionic projectiles and in keV for the others.

Double Differential Cross Sections (DDCS)

Interaction <ia>={ 'l,d' | 'x,d' | 'i,d' } is foreseen for double differential (energy,angle) cross sections.
The common EM cross section file header is followed by:
!projectile   <projectile>

!shell      <shell-number_1>
!eproj      <E_proj_1_1> [<E_loss>]
!esec       <E_sec_1_1_1>
<cos(theta)> <dsigma_di/dE/dOmega/cm**2/keV/sr>  
...
!esec       <E_sec_1_1_2>
<cos(theta)> <dsigma_di/dE/dOmega/cm**2/keV/sr>  
...
!eproj      <E_proj_1_2> [<E_loss>]
!esec       <E_sec_1_2_1>
<cos(theta)> <dsigma_di/dE/dOmega/cm**2/keV/sr>  
...
!esec       <E_sec_1_2_2>
<cos(theta)> <dsigma_di/dE/dOmega/cm**2/keV/sr>  
...

!shell      <shell-number_2>
!eproj      <E_proj_2_1> [<E_loss>]
!esec       <E_sec_2_1_1>
<cos(theta)> <dsigma_di/dE/dOmega/cm**2/keV/sr>  
...
!esec       <E_sec_2_1_2>
<cos(theta)> <dsigma_di/dE/dOmega/cm**2/keV/sr>  
...
!eproj      <E_proj_2_2> [<E_loss>]
!esec       <E_sec_2_2_1>
<cos(theta)> <dsigma_di/dE/dOmega/cm**2/keV/sr>  
...
!esec       <E_sec_2_2_2>
<cos(theta)> <dsigma_di/dE/dOmega/cm**2/keV/sr>  
...
Partial cross sections for the different atomic or molecular electronic shells of the target may be given. Use !shell 0 for the sum of all shells.
The projectile energy <E_proj> is given in MeV/u for ionic projectiles and in keV for the others.
The secondary electron energy <E_sec> is given in keV.
The usual file name extension is .<ia>.xs. Some formal examples for total, single and double differential cross sections.

Nuclear interactions

Not yet implemented, draft only, subject to change

Supported from !fileversion 20130131 onwards.

Nuclear reaction cross section

These describe the total cross section for interactions leading to the "loss" of the projectile. The interaction type <ia> is specified as nr,t. The common file header is followed by:
   !target      <nuclide>
   #
   # optional comment
   #

   !projectile   <projectile_1>
   !sigtot     [<expression>]
   # E [MeV/u]  sigma_nf [mbarn] 
   <E/(MeV/u)> <sigma_nf [mbarn]> 
   ...
   !sigtot     [<expression>]
   # E [MeV/u]  sigma_nf [mbarn] 
   <E/(MeV/u)> <sigma_nf [mbarn]> 
   ...

   !projectile   <projectile_2>  
   !sigtot     [<expression>]
   # E [MeV/u]  sigma_nf [mbarn] 
   <E/(MeV/u)> <sigma_nf [mbarn]> 
   ...

   !projectile   <projectile_n>  
   ...
<projectile> is specified as a nuclide. <expression> allows simple modification of the respective cross section, but currently only a single factor (e.g. '*1.55') is supported.

Nuclear fragmentation

The common file header is followed by:
   !target      <nuclide>
   #
   # optional comment
   #

   !projectile   <projectile_1>
   !fragment     <fragment_1_1> [<expression>]
   # E [MeV/u]  sigma_nf [mbarn] 
   <E/(MeV/u)> <sigma_nf [mbarn]> 
   ...
   !fragment     <fragment_1_2> [<expression>]
   # E [MeV/u]  sigma_nf [mbarn] 
   <E/(MeV/u)> <sigma_nf [mbarn]> 
   ...

   !projectile   <projectile_2>  
   !fragment     <fragment_2_1> [<expression>]
   # E [MeV/u]  sigma_nf [mbarn] 
   <E/(MeV/u)> <sigma_nf [mbarn]> 
   ...

   !projectile   <projectile_n>  
   ...
The interaction type <ia> is specified as nf,t. <projectile> and <fragment> are specified as nuclides. <expression> allows simple modification of the respective fragmentation cross section, but currently only a single factor (e.g. '*1.55') is supported.

Last updated: M.Kraemer,
$Id: traxfmtxs.html,v 1.3 2015/04/23 15:23:07 kraemer Exp $