THERMINATOR 2: THERMal heavy IoN generATOR 2
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文摘
We present an extended version of THERMINATOR, a Monte Carlo event generator dedicated to studies of the statistical production of particles in relativistic heavy-ion collisions. The package is written in C++ and uses the CERN ROOT data-analysis environment. The largely increased functionality of the code contains the following main features: 1) The possibility of input of any shape of the freeze-out hypersurface and the expansion velocity field, including the -dimensional profiles, in particular those generated externally with various hydrodynamic codes. 2) The hypersurfaces may have variable thermal parameters, which allow studies departing significantly from the mid-rapidity region where the baryon chemical potential becomes large. 3) We include a library of standard sets of hypersurfaces and velocity profiles describing the RHIC Au + Au data at for various centralities, as well as those anticipated for the LHC Pb + Pb collisions at . 4) A separate code, FEMTO-THERMINATOR, is provided to carry out the analysis of the pion-pion femtoscopic correlations which are an important source of information concerning the size and expansion of the system. 5) We also include several useful scripts that carry out auxiliary tasks, such as obtaining an estimate of the number of elastic collisions after the freeze-out, counting of particles flowing back into the fireball and violating causality (typically very few), or visualizing various results: the particle -spectra, the elliptic flow coefficients, and the HBT correlation radii.

Program summary

Program title: THERMINATOR 2

Catalogue identifier: ADXL_v2_0

Program summary URL:

Program obtainable from: CPC Program Library, Queen?s University, Belfast, N. Ireland

Licensing provisions: Standard CPC licence,

No. of lines in distributed program, including test data, etc.: 423?44

No. of bytes in distributed program, including test data, etc.: 2?54?02

Distribution format: tar.gz

Programming language: C++ with the CERN ROOT libraries, BASH shell

Computer: Any with a C++ compiler and the CERN ROOT environment, ver. 5.26 or later, tested with Intel Core2 Duo CPU E8400 @ 3 GHz, 4 GB RAM

Operating system:

Linux Ubuntu 10.10 x64 (gcc 4.4.5) ROOT 5.26

Linux Ubuntu 11.04 x64 (gcc Ubuntu/Linaro 4.5.2-8ubuntu4) ROOT 5.30/00 (compiled from source)

Linux CentOS 5.2 (gcc Red Hat 4.1.2-42) ROOT 5.30/00 (compiled from source)

Mac OS X 10.6.8 (i686-apple-darwin10-g++-4.2.1) ROOT 5.30/00 (for Mac OS X 10.6 x86-64 with gcc 4.2.1)

cygwin-1.7.9-1 (gcc gcc4-g++-4.3.4-4) ROOT 5.30/00 (for cygwin gcc 4.3)

RAM:

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30 MB therm2 events

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150 MB therm2 femto

Classification: 11.2

Catalogue identifier of previous version: ADXL_v1_0

Journal reference of previous version: Comput. Phys. Comm. 174 (2006) 669

External routines: CERN ROOT ()

Does the new version supersede the previous version?: Yes

Nature of problem: Particle production via statistical hadronization in relativistic heavy-ion collisions.

Solution method: Monte Carlo simulation, analyzed with ROOT.

Reasons for new version: The increased functionality of the code contains the following important features. The input of any shape of the freeze-out hypersurface and the expansion velocity field, including the -dimensional profiles, in particular those generated externally with the various popular hydrodynamic codes. The hypersurfaces may have variable thermal parameters, which allows for studies departing significantly from the mid-rapidity region. We include a library of standard sets of hypersurfaces and velocity profiles describing the RHIC Au + Au and the LHC data. A separate code, FEMTO-THERMINATOR, is provided to carry out the analysis of femtoscopic correlations.

Summary of revisions: THERMINATOR 2 incorporates major revisions to encompass the enhanced functionality.

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Classes: The Integrator class has been expanded and a new subgroup of classes defined.

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Model and abstract class: These classes are responsible for the physical models of the freeze-out process. The functionality and readability of the code has been substantially increased by implementing each freeze-out model in a different class.

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The Hypersurface class was added to handle the input form hydrodynamic codes. The hydro input is passed to the program as a lattice of the freeze-out hypersurface. That information is stored in the .xml files.

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Input: THERMINATOR 2 programs are now controlled by *.ini type files. The programs parameters and the freeze-out model parameters are now in separate ini files.

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Output:

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The event files generated by the therm2_events program are not backward compatible with the previous version. The event*.root file structure was expanded with two new TTree structures. From the particle entry it is possible to back-trace the whole cascade.

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Event text output is now optional.

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The ROOT macros produce the *.eps figures with physics results, e.g. the pT-spectra, the elliptic-flow coefficient, rapidity distributions, etc.

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The THERMINATOR HBT package creates the ROOT files femto*.root (therm2_femto) and hbtfit*.root (therm2_hbtfit).

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Directory structure: The directory structure has been reorganized. Source code resides in the build directory. The freeze-out model input files, event files, ROOT macros are stored separately. The THERMINATOR 2 system, after installation, is able to run on a cluster.

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Scripts: The package contains a few BASH scripts helpful when running e.g. on a cluster the whole system can be executed via a single script.

Additional comments: Typical data file size: default configuration.

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45 MB/500 events;

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35 MB/correlation file (one bin);

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45 kB/fit file (projections and fits).

Running time: Default configuration at 3 GHz.

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primordial multiplicities 70 min (calculated only once per case);

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8 min/500 events;

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10 min - draw all figures;

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25 min/one bin in the HBT analysis with 5000 events.

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