Linear Collider Physics List Description
Last modified :
- Modular Physics List and Physics Constructors
- Boson Physics
- Lepton Physics
- Hadron Physics
- Ion Physics
- Decay Physics
Modular Physics List and Physics Constructors
The linear collider physics list contains the best-guess selection
of electromagnetic and hadronic physics processes required to run a
linear collider detector simulation. The processes and models are
organized using a modular physics list
LCPhysicsList.hh ,
LCPhysicsList.cc ,
and a set of physics constructors which allow related physics
processes, models and particles to be grouped together. The
physics constructors handle:
Boson Physics
The boson physics constructor
LCBosonPhysics.hh ,
LCBosonPhysics.cc ,
defines the gamma and two fictitious particles, the Geantino and the
ChargedGeantino.
Four processes are assigned to the gamma:
- conversion to e+ e- pairs
- Compton scattering
- photo-electric effect
- photo-nuclear process
- hadronic models:
- G4GammaNuclearReaction : 0 - 3.5 GeV
- Quark-gluon String with Precompound : 3.0 GeV - 100 TeV
The Geantino is a chargeless, massless, completely non-interacting particle
which can be used for geometry and tracking diagnostics. The ChargedGeantino
is also massless and non-interacting, but has a charge so that it can be
tracked properly in a magnetic field. Aside from the transportation
process, neither of these particles can be assigned an interaction process.
Two hadronic models are required to describe photon interactions with nuclei
and nucleons. Hadronic models are discussed further in
Hadron Physics.
Lepton Physics
The lepton physics constructor
LCLeptonPhysics.hh ,
LCLeptonPhysics.cc ,
defines electrons, muons and taus along with their corresponding neutrinos.
The following processes are assigned to each particle:
- electron:
- multiple scattering
- electron ionization
- electron bremsstrahlung
- electron-nuclear process
- hadronic model:
- electro-nuclear reaction : all energies
- positron:
- multiple scattering
- electron ionization
- electron bremsstrahlung
- positron annihilation
- positron-nuclear process
- hadronic model:
- electro-nuclear reaction : all energies
- mu- :
- multiple scattering
- muon ionization
- muon bremsstrahlung
- e+ e- pair production by muon
- mu+ :
- multiple scattering
- muon ionization
- muon bremsstrahlung
- e+ e- pair production by muon
- tau- :
- multiple scattering
- hadron ionization
- tau+ :
- multiple scattering
- hadron ionization
Note that the ionization and bremsstrahlung processes for e+/e- are
different from those for mu+/mu-. They are specially tuned for the
mass difference and other effects. The hadron ionization process is
used for the tau because of its large mass.
One hadronic model is required to describe electron- and positron-induced
nuclear reactions. The electro-nuclear reaction model relies on the
method of equivalent photons to calculate a virtual photon spectrum, which
in turn is interacted with the nucleus and nucleons using a photo-nuclear
model similar to that in Boson Physics.
The ordering in the above list reflects the process ordering integers used
in the phyiscs list (see code). This ordering is important due to the
coupling between multiple scattering and energy loss processes.
No processes, except transportation, currently exist for the neutrinos.
Caution: Multiple scattering, ionization
and bremsstrahlung processes should always be used together, and in the proper
order. Removing one or more of them from their assigned particles will cause
a crash or at least unpredictable behavior.
Hadron Physics
The hadron physics constructor
LCHadronPhysics.hh ,
LCHadronPhysics.cc ,
defines all stable and long-lived baryons, and all long-lived mesons.
These are the particles that Geant4 can track and therefore require
processes to be assigned. Short-lived particles are not tracked, but
they appear in some hadronic models, so a large list of resonances, quarks
and diquarks is also defined.
In this physics constructor electromagnetic and hadronic processes are
assigned to the long-lived hadrons. For the hadronic processes an extra
level of detail must be addressed. Cross sections and physics models must
be assigned to the various processes before the processes are assigned to
the particles. Default cross sections are provided by Geant4 and will be
used unless otherwise indicated.
For hadron elastic scattering, the same process, G4HadronElasticProcess,
is assigned to all the long-lived hadrons. The hadronic model
which implements this process is G4LElastic, which has its origins in the
GHEISHA model of Geant3. It is used for all incident particle energies.
For hadron inelastic scattering, each long-lived hadron has its own
process. Each of these processes is typically implemented by the combination
of two or more models.
The following processes are assigned to each particle:
- pi+
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 9.9 GeV
- Low Energy Parameterized : 9.5 - 25 GeV
- Quark-gluon String with Precompound : 12 GeV - 100 TeV
- cross sections: G4PiNuclearCrossSection
- pi-
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 9.9 GeV
- Low Energy Parameterized : 9.5 - 25 GeV
- Quark-gluon String with Precompound : 12 GeV - 100 TeV
- cross sections: G4PiNuclearCrossSection
- absorption at rest
- K+
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade: 0 - 13 GeV
- Quark-gluon String with Precompound : 12 GeV - 100 TeV
- K-
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 13 GeV
- Quark-gluon String with Precompound : 12 GeV - 100 TeV
- absorption at rest
- K0L
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 13 GeV
- Quark-gluon String with Precompound : 12 GeV - 100 TeV
- K0S
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 13 GeV
- Quark-gluon String with Precompound : 12 GeV - 100 TeV
- proton
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 9.9 GeV
- Low Energy Parameterized : 9.5 - 25 GeV
- Quark-gluon String with Precompound : 12 GeV - 100 TeV
- cross sections : G4ProtonInelasticCrossSection
- anti-proton
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : 0 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- annihilation at rest
- neutron
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 9.9 GeV
- Low Energy Parameterized : 9.5 - 25 GeV
- Quark-gluon String with Precompound : 12 GeV - 100 TeV
- cross sections : G4NeutronInelasticCrossSection
- neutron induced fission
- neutron capture
- anti-neutron
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : 0 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- annihilation at rest
- lambda
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 13 GeV
- Low Energy Parameterized : 12 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- anti-lambda
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : 0 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- sigma-
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 13 GeV
- Low Energy Parameterized : 12 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- anti-sigma-
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : 0 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- sigma+
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 13 GeV
- Low Energy Parameterized : 12 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- anti-sigma+
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : 0 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- xi-
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 13 GeV
- Low Energy Parameterized : 12 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- anti-xi-
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : 0 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- xi0
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Bertini cascade : 0 - 13 GeV
- Low Energy Parameterized : 12 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- anti-xi0
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : 0 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- omega-
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : 0 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
- anti-omega-
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : 0 - 25 GeV
- High Energy Parameterized : 20 GeV - 10 TeV
Hadronic Models Chosen for this Physics List
The backbone of this, and most, hadronic physics lists consists of the
high energy and low energy parameterized models. They cover all the
long-lived particles at all incident energies. These models are fast
but usually not very detailed. Better models exist, but they do not
apply to all particles at all energies. Where they apply, the better
models are used. For instance, the Bertini cascade model is clearly
better in the energy range 0 - 10 GeV. It is valid for protons,
neutrons, pions, kaons, and hyperons. It is not valid for anti-baryons.
For energies above 12 GeV, the Quark-Gluon String model is best, but it
is only valid for pions, kaons, protons and neutrons.
Ion Physics
The ion physics constructor
LCIonPhysics.hh ,
LCIonPhysics.cc ,
defines deuterons, tritons, 3He and alphas, as well as a generic ion.
The following processes are assigned to each particle:
- deuteron:
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : all energies
- triton:
- multiple scattering
- hadron ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : all energies
- 3He:
- multiple scattering
- ion ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- alpha:
- multiple scattering
- ion ionization
- hadron elastic scattering
- hadronic model:
- G4LElastic : all energies
- hadron inelastic scattering
- hadronic models:
- Low Energy Parameterized : all energies
- generic ion:
- multiple scattering
- ion ionization
Decay Physics
The decay physics constructor
LCDecayPhysics.hh ,
LCDecayPhysics.cc , handles
the decay channels for all unstable particles defined in the physics list.
The same process is assigned to all unstable particles.
Dennis Wright