Version: SMASH-1.8
Changelog

All notable changes to this project will be documented in this file. The format is inspired by Keep a Changelog. This project does not adhere to Semantic Versioning, but it uses versioning inspired by it. Given a version number X.Y.Z,

  • X is incremented for major changes in particular large backwards incompatible updates,
  • Y is incremented for minor changes like an external pull-request that adds one feature and
  • Z for the indication of a bug fix or other very small changes that are not backwards incompatible.

The major categories to group changes in this log are:

  • Input / Output for all, in particular breaking, changes, fixes and additions to the in- and output files.
  • Added for new features.
  • Changed for changes in existing functionality.
  • Fixed for any bug fixes.
  • Removed for now removed features.

Also possible, but for this project less relevant, is Deprecated for soon-to-be removed features.

<a href="https://github.com/smash-transport/smash-devel/compare/SMASH-1.7...SMASH-1.8">SMASH-1.8</a>

Date: 2020-04-07

Input / Output

  • Some column names in the extended ROOT output have changed to be agreement with those in the extended OSCAR output:
    • coll_per_part -> ncoll
    • formation_time -> form_time
    • xsec_factor -> xsecfac
  • Add strangeness and baryon number to VTK particles output.
  • The Only_Final option for the Particles output has the new possibility if IfNotEmpty is entered. Then only output is written if the event is not empty i.e. there was a collision between projectile and target to save disk space. The other two options are now Yes or No (previously True or False).
  • Restructure photon configuration:
    • Add new Photon subsection to Collision_Term section, with options 2to2_Scatterings: True/False, Bremsstrahlung: True/False and Fractional_Photons: Nfrac, where Nfrac is an arbitrary integer
    • Add new Dilepton subsection to Collision_Term, with option Decays: True/False
    • From now on, only the format and whether or not it shall be extended, can be set in the Output subsection Photons.

Added

  • Photon production from pion-pion bremsstrahlung
  • Option to randomize the reaction plane (rotate all particles by a random angle around the z axis).
  • Test to verify that cross sections do not depend on particle order.
  • Various tests for deformed nuclei
  • Various tests for string processes
  • Proper CHANGELOG.md file
  • Option to set up an equilibration time for the box modus, after which the output is written.
  • Most resonance integrals are now cached on disk, reducing the time until the simulation starts.

Changed

  • Extend box examples in user guide to directly run.

Fixed

  • Fix user guide for baryon density dependent symmetry potential.
  • ASCII initial conditions output:
    • Bugfix: write PDG ID instead of unique particle ID.
    • Exclude spectators.
  • Add lower bound for initial conditions proper time.
  • Fix floating point exceptions that were raised if initial conditions output is enabled
  • Fix light nuclei not being affected by potentials

<a href="https://github.com/smash-transport/smash/compare/SMASH-1.6...SMASH-1.7">SMASH-1.7</a>

Date: 2019-10-14

Input / Output

  • New output content: Initial conditions output in ASCII, Oscar, Binary and ROOT format
  • New option to explicitly specify the output times in terms of a list
  • Input option Included_2to2 now has a new possible value NNbar. This is a breaking change since this value now has to be in the included list of 2to2 reactions in order to use the resonances option for NNbar_treatment.
  • Input configuration of deformed nuclei has changed. Additional level of Orientation provided where the angles or a random rotation can be specified. This change is backwards incompatible to config files for SMASH-1.6 or older.
  • Most outputs now specify whether the projectile collided with the target
  • ROOT output now includes charge and optionally the extended output
  • Added particle ID and number of collisions to VTK particles output
  • Thermodynamic output can now also output electric, baryonic and strange currents

Added

  • New stochastic collision criterion (as in A. Lang, H. Babovsky, W. Cassing, U. Mosel, H. G. Reusch, and K. Weber, J. Comp. Phys. 106, 391 (1993)) for 2-to-2 reactions of one particle species with a fixed elastic cross-section.
  • Initial conditions for hydrodynamic simulations can be extracted and are provided in the initial conditions output. The proper time of the produced hypersurface can, if desired, be specified in the configuration file
  • Fermi motion for deformed nuclei
  • Random rotation of custom nuclei
  • Automatic deformation parameters for ruthenium and zirconium
  • Option to add net-baryon density dependence to symmetry potential
  • Option to add high momentum particle into a box calculation

Changed

  • Changed the NN transition region to 3.5-4.5 GeV to better describe the experimental data
  • Box now has minimum length given by the grid size
  • The final-state cross-section output provided by smash -S pdgID1,pdgID2 no longer includes resonances

Fixed

  • Collision finding with frozen Fermi motion: Use beam momentum for collision finding if nuclei have not interacted
  • Fix output time for output at the event end on the command line to always be correct.

<a href="https://github.com/smash-transport/smash/compare/SMASH-1.5.2...SMASH-1.6">SMASH-1.6</a>

Date: 2019-05-24

In- and Output

  • Fix thermodynamic VTK output of the Landau velocity

Added

  • Particle properties updated to use PDG 2018 data (this includes 5 new N* and a new Delta*)
  • Lund fragmentation function for leading baryons in soft non-diffractive string processes
  • Support for customized nuclei: optionally reading in initial nucleon positions in collider modus
  • New density type for charge/isospin and possibility to output the charge currents without smearing
  • Option to place a single high-momentum particle in the center of the sphere modus (~jet)
  • SMASH compiles now also with GCC >= 9, Clang >= 7

Changed

  • No debug output in the default build type, which results in much better performance

Fixed

  • Documentation of formation time
  • Correct declaration of Woods-Saxon distribution for deformed nuclei

<a href="https://github.com/smash-transport/smash/compare/SMASH-1.5.1...SMASH-1.5.2">SMASH-1.5.2</a>

Date: 2019-03-07

Version for JETSCAPE run

Added

  • New tests for density and potential
  • New density type for charge/isospin
  • Added option to propagate a high momentum hadron through the sphere

Changed

  • Exact Pythia version is now required
  • Improve third party infrastructure
  • Default build type amended with one flag
  • Unify functions for EM and hadronic widths of resonances

Fixed

  • Bug fixes related to formation of particles including
    • Correcting the boost
    • Adjust resonance decay times
    • Add unformed particles to grid for collision finding, if they form during the time step

<a href="https://github.com/smash-transport/smash/compare/SMASH-1.5...SMASH-1.5.1">SMASH-1.5.1</a>

Date: 2018-12-04

Changed

  • Documentation of formation time
  • Continuous particle formation for unformed particles from string fragmentation processes

Fixed

  • Correct generic radius for nuclei with A > 16, except for Au, Pb, U, Cu as they are/were exactly specified

<a href="https://github.com/smash-transport/smash/releases/tag/SMASH-1.5">SMASH-1.5</a>

Date: 2018-11-27

First public version of SMASH

Known issues:

  • Simulations at high √sNN above ~30 GeV are slow due to the initialization of Pythia for hard scatterings
  • Strangeness production at intermediate energies is off due to the string excitation and fragmentation (only tuned to pp elementary data)
  • No Coulomb potential is available