Shielding

It is recommended for simulation of deep shielding. Neutrons of 20 MeV and lower use the High Precision neutron models and cross sections to describe elastic and inelastic scattering, capture and fission. The G4NDL database is required for this physics list.

Hadronic Component

The purely hadronic part of this physics list consists of elastic, inelastic, capture and fission processes. Each process is built from a set of cross section sets and interaction models which provide the detailed physics implementation.

Inelastic models

The inelastic hadron-nucleus processes are implemented by the Fritiof parton model (FTF), Bertini and Precompound models. The Bertini intranuclear cascade is responsible for \(p, n, \pi ^+,\ \pi ^-,\ K^+,\ K^-,\ K_L,\ K_S,\ \Lambda ,\ \Sigma ^+,\ \Sigma ^-,\ \Sigma ^0,\ \Xi ^-,\ \Xi ^0\) and \(\Omega ^-\) interactions between 0 to 6 GeV. The FTF model handles these same particles, but over the range 3 GeV to 100 TeV. It also handles anti-protons, anti-neutrons, anti-deuterons, anti-tritons, anti-3He, anti-alphas and anti-hyperons from 0 to 100 TeV/n.

Where Bertini and FTF overlap in particle type and energy range, Bertini is invoked with a probability that decreases linearly from 1.0 to 0.0, and FTF is invoked with the complementary probability.

When the FTF model is used, the Precompound model (P) is also invoked to de-excite the remnant nucleus after the initial high energy interaction. The precompound model in turn calls the Fermi breakup, neutron and light ion evaporation and photon evaporation models as needed. When the Bertini model is used, its own, simpler precompound and de-excitation models are invoked.

Inelastic nucleus-nucleus scattering for all incident A is handled by the Binary Light Ion Cascade (BIC) between 0 and 6 GeV/n, and by the FTF model between 3 GeV/n and 100 TeV/n. The scheme for choosing models in overlapping energy regions is the same as that for FTFP and BERT.

The hadronic interaction of gammas is handled by the photo-nuclear process in which gammas below 6 GeV are interacted using the Bertini cascade, and above 3 GeV by the Quark-gluon String (QGS) model. Muons, electrons and positrons also interact via transfer of virtual photons. These interactions are handled by G4MuonVDNuclearModel and G4ElectroVDNuclearModel which are applied at all energies.

Inelastic cross sections

G4BGGNucleonInelasticXS is used for protons, G4NeutronInelasticXS for neutrons, and G4BGGPionInelasticXS for pions. In these cross sections Barashenkov parameterisation is used below 91 GeV and Glauber-Gribov above.

For kaons, hyperons and anti-hyperons the Glauber-Gribov set (G4ComponentGGHadronNucleusXsc) is used at all energies.

All nucleus-nucleus cross sections are provided by G4ComponentGGNuclNuclXsc at all projectile energies. This class is the Glauber-Gribov nucleus-nucleus cross section parameterisation. When the projectile is an anti-proton, anti-neutron, anti-deuteron, anti-triton, anti-3He or anti-alpha, the G4ComponentAntiNuclNuclearXS class provides the cross sections using the Glauber-Gribov parameterisation.

Hadronic gamma interaction cross sections are supplied by G4PhotoNuclearCrossSection which is used at all gamma energies. G4ElectroNuclearCrossSection is used at all energies for \(e ^+\) and \(e ^-\), while G4KokoulinMuonNuclearXS is used for \(\mu ^+\) and \(\mu ^-\) at all energies.

Elastic models

Elastic scattering of protons and neutrons use G4ChipsElasticModel from 0 to 100 TeV. This model uses the Kossov parameterised cross sections.

For almost all other hadrons the G4HadronElastic model is used for some or all of the energy range. This model is a two-exponential momentum transfer model updated from the old Gheisha code. It is used at all energies by kaons, hyperons, deuterons, tritons, \(^3\)He, alphas and anti-neutrons.

Elastic \(\pi ^+\) and \(\pi ^-\) scattering is implemented by the G4ElasticHadrNucleusHE coherent scattering model for all energies.

For anti-protons, anti-neutrons, anti-deuterons, anti-tritons, anti-\(^3\)He and anti-alphas, G4HadronElastic is used from 0 to 100 MeV/n. Above 100 MeV/n these particles are handled by the G4AntiNuclElastic model.

There is currently no elastic scattering model for nuclear projectiles with \(A > 4\).

Elastic cross sections

G4BGGNucleonElasticXS is used for protons, G4NeutronElasticXS for neutrons, and G4BGGPionElasticXS for pions. In these cross sections Barashenkov parameterisation is used below 91 GeV and Glauber-Gribov above.

For kaons, hyperons, anti-hyperons and light ions the G4ComponentGGNuclNuclXsc elastic cross section is used.

For all ions the G4ComponentGGNuclNuclXsc elastic cross section is used. anti-p, anti-d, anti-t, anti-3He and anti-alpha use the Glauber model cross section in G4ComponentAntiNuclNuclearXS at all energies.

Capture and stopping

Neutron capture uses the G4NeutronRadCapture model with the G4NeutronCaptureXS cross sections. Muon capture or decay at rest is handled by the G4MuonMinusCapture process.

The capture of negative pions and kaons once they have stopped is handled by the BertiniCaptureAtRest model which uses the Bertini cascade. The capture of anti-p, anti-d, anti-t, anti-3He, anti-alpha is handled by the FritiofCaptureAtRest model which uses the Fritiof string model.

Electromagnetic Component

This physics list uses “standard” Geant4 electromagnetic physics as built by the G4EmStandardPhysics constructor. It is implemented for \( \gamma ,\ e^-,\ e^+,\ \mu ^-,\ \mu ^+,\ \tau ^-,\ \tau ^+,\) and all stable charged hadrons/ion (see details in EM physics constructors).

There is no treatment of optical photons in this physics list, optical physics should be added on top of any reference or user custom physics.

Decay Component

The decay of all long-lived hadrons and leptons is handled by the G4Decay process. It does not handle the decay of hadronic resonances like deltas, heavy-flavor particles like D and B mesons or charmed hyperons.

This physics list does invoke the G4RadioactiveDecay process, so unstable ions will be decayed.

Muon capture is handled by the G4MuonMinusCapture process.