11 Detector Simulation
491
11.2.3 Radiation Effects and Background Studies
The background in a modern detector can be due to many factors, including
remnants of past events, accelerator generated backgrounds, and the backscattering
of particles by the detector’s surroundings. These can require simulation, in order
to determine their level and characteristics. Also in many cases effects of the
experiment on its surroundings or its constituents such as activation must be
estimated. Simulation is an essential component.
Tools that are utilized for these tasks include FLUKA and the MARS code [32].
In addition to inclusive physics models, where the whole interaction is simulated,
MARS contains exclusive models, where the leading particles and a sample of other
secondaries is produced by an interaction.
Biasing is a technique in which some ‘unlikely’ trajectories are enhanced by a
large numerical factor and assigned a weight inverse to this factor, in order to rapidly
estimate their effect. It is an essential component of background applications. In
many cases a result cannot be obtained without it; in others it improves greatly the
accuracy of the result. Good statistical accuracy can be achieved within a fraction of
the computation time required for an unbiased, so-called ‘analogue’, calculation
for means and similar observables. Correlations, widths and other second order
observables can be obtained only in some cases and by recording key additional
information during simulation.
MARS has been used for accelerator and background calculations for many
facilities [14] and experiments [33]. FLUKA also has seen wide application in this
domain.
11.3 Components of Detector Simulation
• Geometry description and navigation
• External fields
• Electromagnetic physics models
• Hadronic physics models
• Low-energy neutron interactions
• Accuracy of simulation
• Fast simulation
• Signal generation
• Biasing, production thresholds
A complete tool for simulating particle interactions and detector response must
include the description of a detector’s geometry and material, the input or selection
of primary particles, the modeling of all relevant physical interactions and the
extraction of information such as the energy deposition and particle passage (hits).
491
11.2.3 Radiation Effects and Background Studies
The background in a modern detector can be due to many factors, including
remnants of past events, accelerator generated backgrounds, and the backscattering
of particles by the detector’s surroundings. These can require simulation, in order
to determine their level and characteristics. Also in many cases effects of the
experiment on its surroundings or its constituents such as activation must be
estimated. Simulation is an essential component.
Tools that are utilized for these tasks include FLUKA and the MARS code [32].
In addition to inclusive physics models, where the whole interaction is simulated,
MARS contains exclusive models, where the leading particles and a sample of other
secondaries is produced by an interaction.
Biasing is a technique in which some ‘unlikely’ trajectories are enhanced by a
large numerical factor and assigned a weight inverse to this factor, in order to rapidly
estimate their effect. It is an essential component of background applications. In
many cases a result cannot be obtained without it; in others it improves greatly the
accuracy of the result. Good statistical accuracy can be achieved within a fraction of
the computation time required for an unbiased, so-called ‘analogue’, calculation
for means and similar observables. Correlations, widths and other second order
observables can be obtained only in some cases and by recording key additional
information during simulation.
MARS has been used for accelerator and background calculations for many
facilities [14] and experiments [33]. FLUKA also has seen wide application in this
domain.
11.3 Components of Detector Simulation
• Geometry description and navigation
• External fields
• Electromagnetic physics models
• Hadronic physics models
• Low-energy neutron interactions
• Accuracy of simulation
• Fast simulation
• Signal generation
• Biasing, production thresholds
A complete tool for simulating particle interactions and detector response must
include the description of a detector’s geometry and material, the input or selection
of primary particles, the modeling of all relevant physical interactions and the
extraction of information such as the energy deposition and particle passage (hits).