12,449 research outputs found
Re-engineering a nanodosimetry Monte Carlo code into Geant4: software design and first results
A set of physics models for nanodosimetry simulation is being re-engineered
for use in Geant4-based simulations. This extension of Geant4 capabilities is
part of a larger scale R&D project for multi-scale simulation involving
adaptable, co-working condensed and discrete transport schemes. The project in
progress reengineers the physics modeling capabilities associated with an
existing FORTRAN track-structure code for nanodosimetry into a software design
suitable to collaborate with an object oriented simulation kernel. The first
experience and results of the ongoing re-engineering process are presented.Comment: 4 pages, 2 figures and images, to appear in proceedings of the
Nuclear Science Symposium and Medical Imaging Conference 2009, Orland
The Virtual Monte Carlo
The concept of Virtual Monte Carlo (VMC) has been developed by the ALICE
Software Project to allow different Monte Carlo simulation programs to run
without changing the user code, such as the geometry definition, the detector
response simulation or input and output formats. Recently, the VMC classes have
been integrated into the ROOT framework, and the other relevant packages have
been separated from the AliRoot framework and can be used individually by any
other HEP project. The general concept of the VMC and its set of base classes
provided in ROOT will be presented. Existing implementations for Geant3, Geant4
and FLUKA and simple examples of usage will be described.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 8 pages, LaTeX, 6 eps figures. PSN
THJT006. See http://root.cern.ch/root/vmc/VirtualMC.htm
Generation of Warm Dense Plasma on Solar Panel Infrastructure in Exo-Atmospheric Conditions
The use of a weaponized thermo-nuclear device in exo-atmospheric conditions would be of great impact on the material integrity of orbiting satellite infrastructure. Particular damage would occur to the multi-layered, solar cell components of such satellites. The rapid absorption of X-ray radiation originating from a nuclear blast into these layers occurs over a picosecond time scale and leads to the generation of Warm Dense Plasma (WDP). While incredibly difficult and costly to replicate in a laboratory setting, a collection of computational techniques and software libraries may be utilized to simulate the intricate atomic and subatomic physics characteristics of such an event. Use of the Monte Carlo sampling method within the Geant4 software library allows for the energy deposition and power density profiles by X-rays into this system to be determined. By understanding and modeling the different factors which can affect the absorption of thermonuclear X-ray radiation, specifically, “cold –X-ray radiation,” in the energy range of approximately 1 to 1.5 keV, the molecular dynamics modeling of WDP generation and evolution can be performed using the LAMMPS code library. One aspect modeled and utilized within this software is the Planck blackbody spectrum of X-rays, assumed to be emitted by the detonation. Another such factor explored is the effect of primary and secondary particle backscattering within the active solar cell layer. Ultimately, it was determined that the primary and secondary particle backscattering of photons and electrons occurs at such a relatively low rate that its effect on the properties of the generated WDP is negligible. Once the energy deposition and power density profiles are determined, LAMMPS is utilized in order to understand the spatio-temporal evolution of the WDP as well as the temperature, stress, and mass density distribution within the material, at its surface, and its immediate vacuum surroundings
GPU in Physics Computation: Case Geant4 Navigation
General purpose computing on graphic processing units (GPU) is a potential
method of speeding up scientific computation with low cost and high energy
efficiency. We experimented with the particle physics simulation toolkit Geant4
used at CERN to benchmark its geometry navigation functionality on a GPU. The
goal was to find out whether Geant4 physics simulations could benefit from GPU
acceleration and how difficult it is to modify Geant4 code to run in a GPU.
We ported selected parts of Geant4 code to C99 & CUDA and implemented a
simple gamma physics simulation utilizing this code to measure efficiency. The
performance of the program was tested by running it on two different platforms:
NVIDIA GeForce 470 GTX GPU and a 12-core AMD CPU system. Our conclusion was
that GPUs can be a competitive alternate for multi-core computers but porting
existing software in an efficient way is challenging
Physics-related epistemic uncertainties in proton depth dose simulation
A set of physics models and parameters pertaining to the simulation of proton
energy deposition in matter are evaluated in the energy range up to
approximately 65 MeV, based on their implementations in the Geant4 toolkit. The
analysis assesses several features of the models and the impact of their
associated epistemic uncertainties, i.e. uncertainties due to lack of
knowledge, on the simulation results. Possible systematic effects deriving from
uncertainties of this kind are highlighted; their relevance in relation to the
application environment and different experimental requirements are discussed,
with emphasis on the simulation of radiotherapy set-ups. By documenting
quantitatively the features of a wide set of simulation models and the related
intrinsic uncertainties affecting the simulation results, this analysis
provides guidance regarding the use of the concerned simulation tools in
experimental applications; it also provides indications for further
experimental measurements addressing the sources of such uncertainties.Comment: To be published in IEEE Trans. Nucl. Sc
Radioactive Decays in Geant4
The simulation of radioactive decays is a common task in Monte-Carlo systems
such as Geant4. Usually, a system either uses an approach focusing on the
simulations of every individual decay or an approach which simulates a large
number of decays with a focus on correct overall statistics. The radioactive
decay package presented in this work permits, for the first time, the use of
both methods within the same simulation framework - Geant4. The accuracy of the
statistical approach in our new package, RDM-extended, and that of the existing
Geant4 per-decay implementation (original RDM), which has also been refactored,
are verified against the ENSDF database. The new verified package is beneficial
for a wide range of experimental scenarios, as it enables researchers to choose
the most appropriate approach for their Geant4-based application
Bertini intra-nuclear cascade implementation in Geant4
We present here a intra-nuclear cascade model implemented in Geant4 5.0. The
cascade model is based on re-engineering of INUCL code. Models included are
Bertini intra-nuclear cascade model with exitons, pre-equilibrium model,
nucleus explosion model, fission model, and evaporation model. Intermediate
energy nuclear reactions from 100 MeV to 3 GeV energy are treated for proton,
neutron, pions, photon and nuclear isotopes. We represent overview of the
models, review results achieved from simulations and make comparisons with
experimental data.Comment: Computing in High Energy and Nuclear Physics, La Jolla, California,
March 24-28, 2003 1 tar fil
Quantitative Test of the Evolution of Geant4 Electron Backscattering Simulation
Evolutions of Geant4 code have affected the simulation of electron
backscattering with respect to previously published results. Their effects are
quantified by analyzing the compatibility of the simulated electron
backscattering fraction with a large collection of experimental data for a wide
set of physics configuration options available in Geant4. Special emphasis is
placed on two electron scattering implementations first released in Geant4
version 10.2: the Goudsmit-Saunderson multiple scattering model and a single
Coulomb scattering model based on Mott cross section calculation. The new
Goudsmit-Saunderson multiple scattering model appears to perform equally or
less accurately than the model implemented in previous Geant4 versions,
depending on the electron energy. The new Coulomb scattering model was flawed
from a physics point of view, but computationally fast in Geant4 version 10.2;
the physics correction released in Geant4 version 10.2p01 severely degrades its
computational performance. Evolutions in the Geant4 geometry domain have
addressed physics problems observed in electron backscattering simulation in
previous publications.Comment: To be published in IEEE Trans. Nucl. Sc
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