Reference Physics Lists

A web page recommending physics lists according to the use case is under construction.

String model based physics lists

These Physics lists apply a string model for the modeling of interactions of high energy hadrons, i.e. for protons, neutrons, pions and kaons above ~(5-25) GeV depending on the exact physics list. Interactions at lower energies are handled by one of the intranuclear cascade models or the precompound model. Nuclear capture of negative particles and neutrons at rest is handled using either the Chiral Invariant Phase Space (CHIPS) model or the Bertini intranuclear cascade. Hadronic inelastic interactions use:

  • a tabulation of the Barashenkov pion cross sections
  • the Axen-Wellisch parameterization of the proton and neutron cross sections

The physics lists are:

  • QGSP and QGSP_EMV
    QGSP is the basic physics list applying the quark gluon string model for high energy interactions of protons, neutrons, pions, and Kaons and nuclei. The high energy interaction creates an exited nucleus, which is passed to the precompound model modeling the nuclear de-excitation.

    QGSP_EMV is identical to QGSP, but parameters of electromagnetic processes tuned to yield better cpu performance with only slightly less precision.

  • QGSC and QGSC_EMV
    As QGSP except applying CHIPS modeling for the nuclear de-excitation. In comparison to thin target experiments, this improves simulation of the nuclear de-excitation part of the interaction, resulting in slightly increased production of relatively low energy secondary protons (and neutrons).

    QGSC_EMV is identical to QGSC, but parameters of electromagnetic processes tuned to yield better cpu performance with only slightly less precision.

  • QGSP_EFLOW
    This variant of QGSC uses a different algorithm setting up the excited nucleus created by the high energy interaction resulting in a good description of target fragmentation products; comparisons to thin target data well reproduce the proton production rate in the nuclear fragmentation region.
  • QGSP_BERT and QGSP_BERT_EMV
    Like QGSP, but using Geant4 Bertini cascade for primary protons, neutrons, pions and Kaons below ~10GeV. In comparison to experimental data we find improved agreement to data compared to QGSP which uses the low energy parameterised (LEP) model for all particles at these energies. The Bertini model produces more secondary neutrons and protons than the LEP model, yielding a better agreement to experimental data.

    QGSP_BERT_EMV is like QGSP_BERT, but parameters of electromagnetic processes tuned to yield better cpu performance with only slightly less precision.

    Both QGSP_BERT and QGSP_BERT_EMV are less CPU performant as QGSP.

  • QGSP_BERT_HP
    This list is similar to QGSP_BERT and in addition uses the data driven high precision neutron package (NeutronHP) to transport neutrons below 20 MeV down to thermal energies.
  • QGSP_BERT_TRV
    This is a variant of QGSP_BERT where the Geant4 Bertini cascade is only used for particles below ~5.5 GeV.
  • QGSP_BIC and QGSP_BIC_HP
    Like QGSP, but using Geant4 Binary cascade for primary protons and neutrons with energies below ~10GeV, thus replacing the use of the LEP model for protons and neutrons In comparison to the LEP model, Binary cascade better describes production of secondary particles produced in interactions of protons and neutrons with nuclei.

    Both lists, QGSP_BIC and QGSP_BIC_HP, also use the binary light ion cascade to model inelastic interaction of ions up to few GeV/nucleon with matter.

    The list QGSP_BIC_HP is like QGSP_BIC with the addition to use the data driven high precision neutron package (NeutronHP) to transport neutrons below 20 MeV down to thermal energies.

  • QGSP_NEQ, QGSP_EMV_NQE, and QGSP_BERT_NQE
    These lists correspond to the lists without the trailing _NQE, except that here the quasi-elastic channel for high energy inelastic reactions is ignored. This quasi-elastic channel was missing from string model based physics lists prior to release 8.3. To allow comparison to results obtained with older releases of Geant4, i.e. 8.2 and before, these lists are provided for a transisition period.
     
  • QGSP_INCLXX
    This is an experimental physics list that uses the Liege Intranuclear Cascade model (INCL++) for proton-, neutron- and pion-induced reactions below ~3 GeV, instead of BERT or BIC. INCL++ is also used for reactions induced by light nuclei (up to A=18).
     
  • FTFP_BERT, FTFP, FTFP_EMV
    In FTF physics lists, a different string model is used. The FTF model is based on the FRITIOF description of string excitation and fragmentation.