Causal Viscous Hydro Code for Non-Central Heavy Ion Collisions

by

Ulrike Romatschke and Paul Romatschke

version beta May 2007

Warning: the code is still being developed. Please check with
us via email whether there has been a new release.


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Compiling the code:


* the hydro-code is in the zipped-tar file named 

UVH2+1.tgz

It uses the gsl-library (version 1.8) obtainable from 

http://www.gnu.org/software/gsl/

The hydro code expects the link "gsl" in the directory to point to 
the gsl directory.

You should then be able to compile the different moduls of the code:

make initE
make vh2
make convert
make extract

* the particle decay routines (adapted from AZHYDRO) are in the
zipped-tar file named 

reso.tgz

Put it into a separate directory where you should be able to compile
it with "make". Then take the executable "reso" and put it into the 
hydro directory 


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Using the code:

* Read the disclaimer in UVH2+1.cpp

* The code is separated into several modules:

 1) initE: this module produces the initial energy-density
distribution in the transverse plane. The current version
lets you play with different versions of the Glauber initial
condition parametrization. 

Output: initE produces the file "inited.dat"

2) vh2: this is the main hydro code. It takes the output
from running initE as an input for the energy density
and then solves the hydro equations until freeze-out is finished.
It puts snapshots of things like the energy-density profile
into the directory "data/snapshots", and 
the eccentricities into "ecc.dat" in "data/"

Output: freezeout.dat

3) convert: this module converts the hydrodynamic 
degrees of freedom (energy density, fluid velocities,...) 
into particle spectra using the Cooper-Frye freeze-out prescription

Output: phipspectra.dat, ptarr.dat

4) reso: this module (adapted from the AZHYDRO code) takes the
particle spectra and calculates decays of unstable particles
using the particle data book values.
Output: spec_ and PT_ files in "data/results"
(see pdg_weak.dat for a clue what the numbers mean)

5) extract: this module finally takes the stable particle
spectra and calculates dN/dy/d^2pt (alias "v0"), "v2" and "v4"
from them. These can then be further manipulated to give
the total multiplicity and integrated/min-bias v2

* The man control-file of the code is called "params.txt"
and can be found in the "data/" subdirectory. It has
most of the adjustable switches in there and a minimal description
to them. The physics parameters should be self-explanatory anyway.

* For convenience, once you've specified the relevant
parameters you're interested in in "params.txt", you can
simply invoke the shell-script "exshell", which should
do the steps 1)-5) for you and you can simply look at the
results in "data/results".

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If something does not work or you think that I forgot to
mention something important, let me know!
Have fun.

31 Oct 2007 --- Paul Romatschke