UrQMD for BRAHMS

General Information
The input file
The output file
More information

General Information

The URQMD model is a transport model for simulating heavy ion collisions in the energy range from 50 MeV/nucleon up 200 to GeV/nucleon. It runs of various UNIX-based computing platforms. Current implementations include GNU G77 (Linux, AIX). This version has been adapted for BRAHMS_CVS.
RQMD is designed as multipurpose tool for studying a wide variety of heavy ion related effects ranging from multifragmentation and collective effects up to particle production and correla tions.
This document is an introduction to use of URQMD in the frame of BRAHMS Collaborations.
Its purpose is to serve as a short guide to the experienced heavy ion physicist on how to run the program.
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The input file

The figure shows a typical input-file for URQMD . The general format of the inputfile is 1A3,1IA77. This means that every input line consists of two sections: First a three character flag followed by a 77 character string, the contents of which varies according to the flag specified. Input file is located in $(URQMD_HOME)/lib and is named "inputfile"

# this is a sample input file for uqmd

# projectile

# Ap Zp

pro 197 79

# optional: special projectile: ityp, iso3

# PRO 101 2

# target

# At Zt

tar 197 79

# number of events

nev 100

# time to propagate and output time-interval (in fm/c)

tim 40 40

# incident beam energy in AGEV

ecm  200.

imp  3.0

#equation of state

eos  0        # CASCADE mode

# some options and parameters

cto  4 1        output of initialization

ctp  I I.dO       scaling for decay width of Resonances

fl5 # no output to filel5

# end of file

xxx

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The output file

The output file of UrQMD adapted for BRAHMS is the OSC1997A format.

The file-header look like:

OSC1997A

final_id_p_x

UrQMD 1.0 (197, 79)+(197, 79) eqsp 2.00E+02 1

The event line lists:

event npart b phi

event = the number of event;
npart = the number of particles in the event;
b = the impact parameter;
phi = the azimuthal angle

The particle line lists:

nrcrt id px py pz E m xf yf zf tf

id = ID of particle
px,py,pz,E = 4-momentum vector of particle [GeV]
m = mass of particle [GeV]
xf,yf,zf = freeze-out coordinate location [fm]
tf = freeze-out time of particle [fm/c]

You can select from the next id particle specificatins.
Example:

particle	ID
pi-	-211
pi+	211
k+	321
k-	-321
p	2212
pbar	-2212
n	2112

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