THERMINATOR 2: THERMal heavy IoN generATOR 2

Abstract

We present an extended version of THERMINATOR, a Monte Carlo event generator dedicated to studies of the statistical production of particles in relativistic heavyion 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 √ s N N = 200 GeV for various centralities, as well as those anticipated for the LHC Pb+Pb collisions at √ s N N = 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.

Multipion Bose-Einstein correlations inpp,p-Pb, and Pb-Pb collisions at energies available at the CERN Large Hadron Collider

“…(10) The two-pion FSI factor of pair (i,j ) is given by K 2 (q ij ) and is calculated by averaging the modulus squared of the Coulomb and strong wave function over an assumed freeze-out distribution. We use the THERMINATOR model of particle production as an estimate for the freeze-out distribution [37,38]. The pair-product approach to three-pion FSI correlations was shown to be a good approximation to the full asymptotic wave function calculation [19,24].…”

Recent progress in anisotropic hydrodynamics

“…From each of these results, a freeze-out hypersurface corresponding to a fixed effective temperature was extracted. The microscopic parameters α, u, and λ on the hypersurface were then fed to a version of THERMINATOR 2 which had been modified to account for an ellipsoidal distribution function [30]. THERMINATOR 2 produces sampled event-by-event hadronic production from the exported freezeout hypersurface and also performs hadronic feed down (resonance decays) for each sampled event.…”

Study of Hyperon Interaction from Heavy-Ion Collisions using STAR Detector at RHIC

“…The feed down contribution from Σ hyperon is difficult to estimate as its reconstruction is not possible in our experiment. Studies based on THERMINATOR2 [23] model show that 20% of the Λ hyperons in the sample are from Σ 0 decays, 26% from Σ * decays and Ξ decays contribute roughly 25%. For the spectra analysis of the Λ hyperon, contributions from Ξ decays are generally corrected using the experimentally measured Ξ − , Ξ 0 (1530) spectra [24].…”