The iEBE-VISHNU code package for relativistic heavy-ion collisions

Abstract

The iEBE-VISHNU code package performs event-by-event simulations for relativistic heavy-ion collisions using a hybrid approach based on (2+1)-dimensional viscous hydrodynamics coupled to a hadronic cascade model. We present the detailed model implementation, accompanied by some numerical code tests for the package. iEBE-VISHNU forms the core of a general theoretical framework for model-data comparisons through large scale Monte-Carlo simulations. A numerical interface between the hydrodynamically evolving medium and thermal photon radiation is also discussed. This interface is more generally designed for calculations of all kinds of rare probes that are coupled to the temperature and flow velocity evolution of the bulk medium, such as jet energy loss and heavy quark diffusion. Program summaryProgram title: iEBE-VISHNUCatalogue identifier: AEYA_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEYA_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 5257939No. of bytes in distributed program, including test data, etc.: 262822421Distribution format: tar.gzProgramming language: Fortran, C++, python, bash, SQLite.Computer: Laptop, desktop, cluster.Operating system: Tested on GNU/Linux Ubuntu 12.04 x64, Red Hat Linux 6, Mac OS X 10.8+.RAM: 2G bytesClassification: 17.11, 17.16, 17.20.External routines: GNU Scientific Library (GSL), HDF5 (Fortran and C++ enabled), NumpyNature of problem: Relativistic heavy-ion collisions are tiny in size (V≈10−42m3) and live in a flash (∼5×10−23s). It is impossible to use external probes to study the properties of the quark-gluon plasma (QGP), a novel state of matter created during the collisions. Experiments can only measure the momentum information of stable hadrons, who are the remnants of the collisions. In order to extract the thermal and transport properties of the QGP one needs to rely on Monte-Carlo event-by-event model simulations, which reverse-engineer the experimental measurements to the early time dynamics of the relativistic heavy-ion collisions.Solution method: Relativistic heavy-ion collisions contain multiple stages of evolution. The physics that governs each stage is implemented into individual code components. A general driver script glues all the modular packages as a whole to perform large-scale Monte-Carlo simulations. The final results are stored into SQLite database, which supports standard querying for massive data analysis. By tuning transport coefficients of the QGP as free parameters, e.g. the specific shear viscosity η/s, we can constrain various transport properties of the QGP through model-data comparisons.Additional comments: !!!!! The distribution file for this program is over 260 Mbytes and therefore is not delivered directly when download or Email is requested. Instead a html file giving details of how the program can be obtained is sent. !!!!!Running time: The following running time is tested on a laptop computer with a 2.4 GHz Intel Core i5 CPU, 4 GB memory. All the C++ and Fortran codes are compiled with the GNU Compiler Collection (GCC) 4.9.2 and -O3 optimization (Table 1).