THERMINATOR 2: THERMal heavy IoN generATOR 2

TL;DR

THERMINATOR 2 is an advanced Monte Carlo event generator for simulating particle production in relativistic heavy-ion collisions, featuring flexible input models, analysis tools, and applications to RHIC and LHC data.

Contribution

It extends the original THERMINATOR by allowing arbitrary freeze-out hypersurfaces, velocity fields, and detailed femtoscopic analysis, enabling more realistic and comprehensive collision simulations.

Findings

Supports 3+1D profiles from hydrodynamic models

Includes standard hypersurface libraries for RHIC and LHC

Provides tools for analyzing femtoscopic correlations

Abstract

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 increased functionality of the code contains the following features: The input of any shape of the freeze-out hypersurface and the expansion velocity field, including the 3+1 dimensional profiles, in particular those generated externally with various hydrodynamic codes. The hypersufraces may have variable thermal parameters, which allows for studies departing significantly from the mid-rapidity region, where the baryon chemical potential becomes large. We include a library of standard sets of hypersurfaces and velocity profiles describing the RHIC Au+Au data at sqrt(s_(NN)) = 200 GeV for various centralities, as well as those anticipated for the LHC Pb+Pb collisions at sqrt(s_(NN)) = 5.5 TeV. A separate code, FEMTO-THERMINATOR, is provided to carry out the analysis of femtoscopic correlations which are an important source of information concerning the size and expansion of the system. 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 p_T-spectra, the elliptic flow coefficients, and the HBT correlation radii. We also investigate the problem of the back-flow of particles into the hydrodynamic region, as well as estimate the elastic rescattering in terms of trajectory crossings. The package is written in C++ and uses the CERN ROOT environment.