Output Configuration

Description of options

To produce a certain output content it is necessary to explicitly configure it in the Output section of the configuration file. This means, that the Output section needs to contain a subsection for the desired output. Aditionally, there are general output configuration parameters.

General output configuration parameters:

Output_Interval (double, optional, default = End_Time):
Defines the period of intermediate output of the status of the simulated system in Standard Output and other output formats which support this functionality.

Output_Times (doubles, optional, no default):
Explicitly defines the the times where output is generated in the form of a list. Cannot be used in combination with Output_Interval. Output times outside the simulation time are ignored. The following example will produce output at event start, event end and at the specified times as long as they are within the simulation time.

Output:
    Output_Times: [-0.1, 0.0, 1.0, 2.0, 10.0]

Density_Type (string, optional, default = "none"):
Determines which kind of density is printed into the headers of the collision files. Possible values:

• "hadron" - Total hadronic density
• "baryon" - Net baryon density
• "baryonic isospin" - Baryonic isospin density
• "pion" - Pion density
• "none" - Do not calculate density, print 0.0

Format configuration independently of the specific output content

Further options are defined for every single output content (see output contents for the list of possible contents). Independently of the content, it is always necessary to provide the format in which the output should be generated.

Format (list of formats, optional, default = [ ]):
List of formats for writing particular content. Possible formats for every content are listed and described in output contents. List of available formats is here.
Besides the universal Format option, there are also content-specific output options that are listed below.

Content-specific output options

• Particles
  Extended (bool, optional, default = false, incompatible with Oscar1999, VTK, HepMC and Root formats):
  
  • true - Print extended information for each particle
    
  • false - Regular output for each particle
  Only_Final (string, optional, default = Yes, incompatible with VTK and HepMC format):
  
  • Yes - Print only final particle list
    
  • IfNotEmpty - Print only final particle list, but only if event is not empty (i.e. any collisions happened between projectile and target). Useful to save disk space.
    
  • No - Particle list at output interval including initial time
    
    
• Collisions (VTK not available)
  Extended (bool, optional, default = false, incompatible with Oscar1999, HepMC and Root formats):
  
  • true - Print extended information for each particle
    
  • false - Regular output for each particle
  Print_Start_End (bool, optional, default = false, incompatible with Root and HepMC format):
  
  • true - Initial and final particle list is printed out
    
  • false - Initial and final particle list is not printed out
    
    
• Dileptons (Only Oscar1999, Oscar2013 and binary formats)
  Extended (bool, optional, default = false, incompatible with Oscar1999 format):
  
  • true - Print extended information for each particle
    
  • false - Regular output for each particle
    
    
• Photons (Only Oscar1999, Oscar2013 and binary formats)
  Extended (bool, optional, default = false, incompatible with Oscar1999 format):
  
  • true - Print extended information for each particle
    
  • false - Regular output for each particle
    
    
• Initial_Conditions (Oscar1999, Oscar2013, binary, ROOT and special ASCII IC (ASCII IC Output) formats)
  Proper_Time (double, optional, default = nuclei passing time, if nuclei passing time > Lower_Bound, else Lower_Bound): Proper time at which hypersurface is created
  Lower_Bound (double, optional, default = 0.5 fm): Lower bound for the IC proper time if Proper_Time is not provided.
  Extended (bool, optional, default = false, incompatible with Oscar1999, ROOT and ASCII format):
  
  • true - Print extended information for each particle
  • false - Regular output for each particle
    
    
• Rivet (Only YODA format)
  See Rivet Output User Guide for more information
  
• Coulomb (Only VTK format)
  No content-specific output options
  
  

• Thermodynamics
  The user can print thermodynamical quantities:

  • On the spatial lattice to vtk output. Note, that this output requires a lattice. This lattice needs to be enabled in the conguration file and is regulated by the options of Lattice. See Thermodynamics VTK Output for further information.
  • On the spatial lattice to ASCII output. Note, that this output requires a lattice. This lattice needs to be enabled in the conguration file and is regulated by the options of Lattice. See Thermodynamics Lattice Output for further information.
  • At a given point to ASCII output. See ASCII Thermodynamics Output for further information.
  • Averaged over all particles to ASCII output. See ASCII Thermodynamics Output for further information.

  Type (string, optional, default = "baryon"):
  Particle type taken into consideration, "baryon" corresponds to "net baryon".

  • "hadron"
  • "baryon"
  • "baryonic isospin"
  • "pion"
  • "none"
  • "total isospin"

  Quantities (list of thermodynamic quantities, optional, default = [ ]):
  List of thermodynamic quantities that are printed to the output. Possible quantities are:

  • "rho_eckart" - Eckart rest frame density
  • "tmn" - Energy-momentum tensor \(T^{\mu\nu}(t,x,y,z) \)
  • "tmn_landau" - Energy-momentum tensor in the Landau rest frame. This tensor is computed by boosting \(T^{\mu\nu}(t,x,y,z) \) to the local rest frame, where \(T^{0i} \) = 0.
  • "landau_velocity" - Velocity of the Landau rest frame. The velocity is obtained from the energy-momentum tensor \(T^{\mu\nu}(t,x,y,z) \) by solving the generalized eigenvalue equation \((T^{\mu\nu} - \lambda g^{\mu\nu})u_{\mu}=0 \).
  • "j_QBS" - Electric (Q), baryonic (B) and strange (S) currents \(j^{\mu}_{QBS}(t,x,y,z) \); note that all currents are given in units of "number of charges"; multiply the electric current by the elementary charge \(\sqrt{4 \pi \alpha_{EM}} \) for charge units.

  Position (list of 3 doubles, optional, default = [0.0, 0.0, 0.0]):
  Point, at which thermodynamic quantities are computed.

  Smearing (bool, optional, default = true):
  Using Gaussian smearing for computing thermodynamic quantities or not. This triggers whether thermodynamic quantities are evaluated at a fixed point (true) or summed over all particles (false).

  • true - smearing applied
  • false - smearing not applied

  Only_Participants (bool, optional, default = false):
  If set to true, only participants are included in the computation of the energy momentum tensor and of the Eckart currents. In this context, a hadron is considered as a participant if it had at least one collision. When using Potentials this option must be either left unset or set to false. The reason behing this limitation is that in this case hadrons can influence the evolution of the system even without collisions.

  The contribution to the energy-momentum tensor and current (be it electric, baryonic or strange) from a single particle in its rest frame is:

  \[\begin{eqnarray} j^{\mu} = B \frac{p_0^{\mu}}{p_0^0} W \\ T^{\mu \nu} = \frac{p_0^{\mu}p_0^{\nu}}{p_0^0} W \end{eqnarray}\]

  with B being the charge of interest and W being the weight given to this particle. Normally, if one computes thermodynamic quantities at a point, smearing should be applied, and then W takes on the following shape:

  \[W = (2 \pi \sigma^2)^{-3/2} exp \left(- \frac{(\mathbf{r} - \mathbf{r_0(t)})^2}{2\sigma^2} \right)\]

  It can however be useful to compute the thermo- dynamic quantities of all particles in a box with W = 1, which would correspond to "Smearing: false". Note that using this option changes the units of the thermodynamic quantities, as they are no longer spatially normalized. One should divide this quantity by by the volume of the box to restore units to the correct ones.