11 Detector Simulation
489
relies on external packages: GHEISHA [16], GCALOR [17], which uses CALOR89
[18], and GFLUKA, which interfaces to the 1993 version of FLUKA [19].
FLUKA [20], after a major overhaul in the 1990s, offers microscopic models for
60 elementary particles, all types of ions at energies from 1 keV to 10,000 TeV/A. It
has been used for detector simulation by the Opera and ALICE experiments, in radiation assessment, accelerator collimation and target tuning, and many applications
beyond HEP. A key emphasis and strength have been its single, consistent, core
hadronic model, PEANUT, with a Dual Parton Model (DPM) based high energy
cascade above 5 GeV, a generalized intranuclear cascade and suite of models for the
excited nucleus. For nucleus–nucleus interactions above 5 GeV, it utilizes interfaces
to DPMJET-III [21] event generator for interactions. There is an option for the
detailed treatment of neutrons down to thermal energies, which uses the multigroup approach involving energy bins, and weighted averages of cross sections
and interaction production. Physics processes for electromagnetic interactions and
lepto-nuclear interactions are included. FLUKA focuses on a single set of physics
processes, which are curated and validated extensively by its authors. A small set
of optional variations of physics processes are provided, e.g. for the simulation of
low-energy neutrons. The majority of uses in HEP lie outside detector simulation.
Examples include the estimation of radiation backgrounds in experimental areas,
whether in accelerator facilities or underground halls, and the modeling of beam
interactions with collimators in accelerators. Extensive studies of the LHC radiation
environment have been carried out using it over the past decade, and a FLUKA
model of the full LHC collider is the production simulation for radiation studies.
GEANT4 [13] is the basis of the simulations of BaBar, ATLAS, CMS, LHCb
and a large number of smaller experiments. Its standard configuration provides
electromagnetic interactions for charged particles and gammas down to 1 keV,
hadronic processes for nucleons, mesons and ions, models of electro-nuclear,
lepto-nuclear interactions, radioactive decay of nuclei and optical processes for
photons at visible and near-visible energies. A variety of hadronic processes has
been used to span all projectiles at energies up to 1 TeV, with recent extension
to 100 TeV for Future Circular Collider (FCC) applications [22]. An option for
neutron interactions from 20 MeV down to thermal energies is available using
cross-sections for individual elements and isotopes (a technique called ‘pointwise’). GEANT4 takes a toolkit approach, enabling and requiring its users to
choose the parts required for their application area, including the configuration of
physics models. Recommendations of physics model configurations are provided
for several established type of application and for a number of HEP and external
application domains; validations for several HEP applications have been undertaken
in collaboration with experiments. For other application domains users are invited
to undertake the appropriate validation, potentially using their specific data, and
interacting with GEANT4 experts.
A few other codes provide extensive modeling of multiple particle types,
including the PHITS [23] code and MCNP family. The most recent MCNP version
6 [24, 25] was created from the merger of MCNP5, which focused more on
traditional neutron-gamma applications including simulation of nuclear facilities
489
relies on external packages: GHEISHA [16], GCALOR [17], which uses CALOR89
[18], and GFLUKA, which interfaces to the 1993 version of FLUKA [19].
FLUKA [20], after a major overhaul in the 1990s, offers microscopic models for
60 elementary particles, all types of ions at energies from 1 keV to 10,000 TeV/A. It
has been used for detector simulation by the Opera and ALICE experiments, in radiation assessment, accelerator collimation and target tuning, and many applications
beyond HEP. A key emphasis and strength have been its single, consistent, core
hadronic model, PEANUT, with a Dual Parton Model (DPM) based high energy
cascade above 5 GeV, a generalized intranuclear cascade and suite of models for the
excited nucleus. For nucleus–nucleus interactions above 5 GeV, it utilizes interfaces
to DPMJET-III [21] event generator for interactions. There is an option for the
detailed treatment of neutrons down to thermal energies, which uses the multigroup approach involving energy bins, and weighted averages of cross sections
and interaction production. Physics processes for electromagnetic interactions and
lepto-nuclear interactions are included. FLUKA focuses on a single set of physics
processes, which are curated and validated extensively by its authors. A small set
of optional variations of physics processes are provided, e.g. for the simulation of
low-energy neutrons. The majority of uses in HEP lie outside detector simulation.
Examples include the estimation of radiation backgrounds in experimental areas,
whether in accelerator facilities or underground halls, and the modeling of beam
interactions with collimators in accelerators. Extensive studies of the LHC radiation
environment have been carried out using it over the past decade, and a FLUKA
model of the full LHC collider is the production simulation for radiation studies.
GEANT4 [13] is the basis of the simulations of BaBar, ATLAS, CMS, LHCb
and a large number of smaller experiments. Its standard configuration provides
electromagnetic interactions for charged particles and gammas down to 1 keV,
hadronic processes for nucleons, mesons and ions, models of electro-nuclear,
lepto-nuclear interactions, radioactive decay of nuclei and optical processes for
photons at visible and near-visible energies. A variety of hadronic processes has
been used to span all projectiles at energies up to 1 TeV, with recent extension
to 100 TeV for Future Circular Collider (FCC) applications [22]. An option for
neutron interactions from 20 MeV down to thermal energies is available using
cross-sections for individual elements and isotopes (a technique called ‘pointwise’). GEANT4 takes a toolkit approach, enabling and requiring its users to
choose the parts required for their application area, including the configuration of
physics models. Recommendations of physics model configurations are provided
for several established type of application and for a number of HEP and external
application domains; validations for several HEP applications have been undertaken
in collaboration with experiments. For other application domains users are invited
to undertake the appropriate validation, potentially using their specific data, and
interacting with GEANT4 experts.
A few other codes provide extensive modeling of multiple particle types,
including the PHITS [23] code and MCNP family. The most recent MCNP version
6 [24, 25] was created from the merger of MCNP5, which focused more on
traditional neutron-gamma applications including simulation of nuclear facilities