11 Detector Simulation
523
The GEANT4-DNA package provides new physical models for the description
of elastic and inelastic electromagnetic interactions of electrons and select ions
(Li to O, plus Si and Fe) in liquid water, previously only available in dedicated
‘track structure’ codes such as PARTRAC [147]. In addition, GEANT4-DNA offers
features to model the water radiolysis from ionizing radiation: ionized or excited
water molecules and water anions are generated and tracked at a physicochemical
stage up to a few picoseconds, and subsequently in a ‘chemical’ stage using models
of generation, diffusion and reaction of new chemical species. This is part of an
effort to model and understand the first stages of DNA damage.
11.7 Outlook
During the past decade the application of detector simulation tools has been
significantly widened through the implementation of improved physics models.
Code and models have become more accurate in describing benchmark data. The
need for more accurate data for comparison and model improvement has been
one motivation for some thin-target (HARP, MIPP) and thick target (CALICE)
experiments.
The requirements that arise from the projected use of simulations as an integral
part of the next generation detectors becomes ever stronger. Witness, e.g. the use
of particle flow reconstruction [148] in proposed experiments at the energy frontier,
including the Linear Collider and the Future Circular Collider, to address one of
their major challenges.
The need for further development of physics models for high-energy hadron–
nucleus interactions is evident. Several promising approaches are being pursued,
including the extension and tuning of existing implementations of current models
(Fritiof, Quark-Gluon String), the incorporation of alternative implementations of
existing models, such as QGSJET, complementary modeling approaches (DPMJET)
and the incorporation of new models (EPOS). The availability of high quality thin
target experimental data at energies over a range of momenta from 20 to 158 GeV/c
[149] is an important resource; lack of data for higher energies is a constraint.
In addition to physics improvements, the large increase in statistics of simulated
events for the HL-LHC requires a large improvement in CPU performance, of
approximately a factor of ten. Research in CPU-performance and emerging architectures in the GeantV R&D effort indicate a more realistic target of a factor of 2–4
in performance improvement may be within reach for detailed simulation.
These prospects strengthen the need for parameterized (fast) simulation methods
which can reproduce the results of detailed simulation as accurately as possible,
for use in a majority and potentially an ever-larger fraction of analyses. Hybrid
methods combining parameterized and detailed simulation in innovative ways and
the machine learning approach to parameterized/fast simulation appear amongst the
options which will see significant development and research in the next years.
523
The GEANT4-DNA package provides new physical models for the description
of elastic and inelastic electromagnetic interactions of electrons and select ions
(Li to O, plus Si and Fe) in liquid water, previously only available in dedicated
‘track structure’ codes such as PARTRAC [147]. In addition, GEANT4-DNA offers
features to model the water radiolysis from ionizing radiation: ionized or excited
water molecules and water anions are generated and tracked at a physicochemical
stage up to a few picoseconds, and subsequently in a ‘chemical’ stage using models
of generation, diffusion and reaction of new chemical species. This is part of an
effort to model and understand the first stages of DNA damage.
11.7 Outlook
During the past decade the application of detector simulation tools has been
significantly widened through the implementation of improved physics models.
Code and models have become more accurate in describing benchmark data. The
need for more accurate data for comparison and model improvement has been
one motivation for some thin-target (HARP, MIPP) and thick target (CALICE)
experiments.
The requirements that arise from the projected use of simulations as an integral
part of the next generation detectors becomes ever stronger. Witness, e.g. the use
of particle flow reconstruction [148] in proposed experiments at the energy frontier,
including the Linear Collider and the Future Circular Collider, to address one of
their major challenges.
The need for further development of physics models for high-energy hadron–
nucleus interactions is evident. Several promising approaches are being pursued,
including the extension and tuning of existing implementations of current models
(Fritiof, Quark-Gluon String), the incorporation of alternative implementations of
existing models, such as QGSJET, complementary modeling approaches (DPMJET)
and the incorporation of new models (EPOS). The availability of high quality thin
target experimental data at energies over a range of momenta from 20 to 158 GeV/c
[149] is an important resource; lack of data for higher energies is a constraint.
In addition to physics improvements, the large increase in statistics of simulated
events for the HL-LHC requires a large improvement in CPU performance, of
approximately a factor of ten. Research in CPU-performance and emerging architectures in the GeantV R&D effort indicate a more realistic target of a factor of 2–4
in performance improvement may be within reach for detailed simulation.
These prospects strengthen the need for parameterized (fast) simulation methods
which can reproduce the results of detailed simulation as accurately as possible,
for use in a majority and potentially an ever-larger fraction of analyses. Hybrid
methods combining parameterized and detailed simulation in innovative ways and
the machine learning approach to parameterized/fast simulation appear amongst the
options which will see significant development and research in the next years.