34,415 research outputs found
Particle Flow Calorimetry at the ILC
One of the most important requirements for a detector at the ILC is good jet
energy resolution. It is widely believed that the particle flow approach to
calorimetry is the key to achieving the goal of 0.3/sqrt(E[GeV]). This paper
describes the current performance of the PandoraPFA particle flow algorithm.
For 45 GeV jets in the Tesla TDR detector concept, the ILC jet energy
resolution goal is reached. At higher energies the jet energy resolution
becomes worse and can be described by the empirical expression: sigma_E/E ~
0.265/sqrt(E[GeV]) + 1.2x10^{-4}E[GeV].Comment: 5 pages, 2 .eps figures, to appear in Proc. LCWS06, Bangalore, March
200
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
Validation Test of Geant4 Simulation of Electron Backscattering
Backscattering is a sensitive probe of the accuracy of electron scattering
algorithms implemented in Monte Carlo codes. The capability of the Geant4
toolkit to describe realistically the fraction of electrons backscattered from
a target volume is extensively and quantitatively evaluated in comparison with
experimental data retrieved from the literature. The validation test covers the
energy range between approximately 100 eV and 20 MeV, and concerns a wide set
of target elements. Multiple and single electron scattering models implemented
in Geant4, as well as preassembled selections of physics models distributed
within Geant4, are analyzed with statistical methods. The evaluations concern
Geant4 versions from 9.1 to 10.1. Significant evolutions are observed over the
range of Geant4 versions, not always in the direction of better compatibility
with experiment. Goodness-of-fit tests complemented by categorical analysis
tests identify a configuration based on Geant4 Urban multiple scattering model
in Geant4 version 9.1 and a configuration based on single Coulomb scattering in
Geant4 10.0 as the physics options best reproducing experimental data above a
few tens of keV. At lower energies only single scattering demonstrates some
capability to reproduce data down to a few keV. Recommended preassembled
physics configurations appear incapable of describing electron backscattering
compatible with experiment. With the support of statistical methods, a
correlation is established between the validation of Geant4-based simulation of
backscattering and of energy deposition
Enabling comparison of UrQMD with Geant4 hadronic models
Geant4 has an abundant set of physics models that handle the diverse
interaction of particles with matter across a wide energy range. However, there
are also many well established reaction codes currently used in the same fields
where Geant4 is applied. One such code is the Ultra-relativistic Quantum
Molecular Dynamics (UrQMD) model. In order to take advantage of the UrQMD code,
we create a tool to enable comparisons among UrQMD and Geant4 hadronic models.
This tool allows a user to process the output file of UrQMD through Geant4
toolkit, while at the same time, can choose among different Geant4 hadronic
model generators. As an example, the UrQMD model is compared with the HARP-CDP
experimental data and with the Binary and FRITIOF generators, in the framework
of Geant4. It is shown that the UrQMD model can better reproduce charged pion
production for p+Cu and Pb interactions at 3, 8 and 15 GeV/c, and is a good
candidate for Geant4 hadronic models.Comment: 17 pages, 5 Figure
Direct measurement of neutrons induced in lead by cosmic muons at a shallow underground site
Neutron production in lead by cosmic muons has been studied with a Gadolinium
doped liquid scintillator detector. The detector was installed next to the
Muon-Induced Neutron Indirect Detection EXperiment (MINIDEX), permanently
located in the T\"ubingen shallow underground laboratory where the mean muon
energy is approximately 7 GeV. The MINIDEX plastic scintillators were used to
tag muons; the neutrons were detected through neutron capture and
neutron-induced nuclear recoil signals in the liquid scintillator detector.
Results on the rates of observed neutron captures and nuclear recoils are
presented and compared to predictions from GEANT4-9.6 and GEANT4-10.3. The
predicted rates are significantly too low for both versions of GEANT4. For
neutron capture events, the observation exceeds the predictions by factors of and for GEANT4-9.6
and GEANT4-10.3, respectively. For neutron nuclear recoil events, which require
neutron energies above approximately 5 MeV, the factors are even larger, and , respectively.
Also presented is the first statistically significant measurement of the
spectrum of neutrons induced by cosmic muons in lead between 5 and 40 MeV. It
was obtained by unfolding the nuclear recoil spectrum. The observed neutron
spectrum is harder than predicted by GEANT4. An investigation of the
distribution of the time difference between muon tags and nuclear recoil
signals confirms the validity of the unfolding procedure and shows that GEANT4
cannot properly describe the time distribution of nuclear recoil events. In
general, the description of the data is worse for GEANT4-10.3 than for
GEANT4-9.6.Comment: 29 pages, 22 figures, 4 table
The Geant4-DNA project
The Geant4-DNA project proposes to develop an open-source simulation software
based and fully included in the general-purpose Geant4 Monte Carlo simulation
toolkit. The main objective of this software is to simulate biological damages
induced by ionising radiation at the cellular and sub-cellular scale. This
project was originally initiated by the European Space Agency for the
prediction of deleterious effects of radiation that may affect astronauts
during future long duration space exploration missions. In this paper, the
Geant4-DNA collaboration presents an overview of the whole ongoing project,
including its most recent developments already available in the last Geant4
public release (9.3 BETA), as well as an illustration example simulating the
direct irradiation of a chromatin fibre. Expected extensions involving several
research domains, such as particle physics, chemistry and cellular and
molecular biology, within a fully interdiciplinary activity of the Geant4
collaboration are also discussed.Comment: presented by S. Incerti at the ASIA SIMULATION CONFERENCE 2009,
October 7-9, 2009, Ritsumeikan University, Shiga, Japa
Extending Geant4 Parallelism with External Libraries (MPI, TBB) and Its Use on HPC Resources
With Geant4 Version 10.0, released in December 2013, one of the most widely
used Monte-Carlo codes has been ported to take full advantage of multi- and
many-core CPUs thanks to the introduction of event-level parallelism via
multithreading. In this paper we review recent developments to allow for a
better integration of parallel Geant4 jobs with external libraries. We have
chosen to develop examples using the popular Intel Threading Building Block
(for short TBB) as an alternative parallelization approach to the native Geant4
POSIX. To simplify the scaling of a Geant4 application across nodes on a
cluster we are improving the support of MPI in Geant4. In particular it is now
possible to run an hybrid MPI/MT application that uses MPI to scale across
nodes and MT to scale across cores. %The recent developments allow users to
easily implement parallel application resources that scale on a very large
number of nodes and cores typical of HPC resources.Comment: conferenc
ALICE experience with GEANT4
Since its release in 1999, the LHC experiments have been evaluating GEANT4 in
view of adopting it as a replacement for the obsolescent GEANT3 transport
MonteCarlo. The ALICE collaboration has decided to perform a detailed physics
validation of elementary hadronic processes against experimental data already
used in international benchmarks. In one test, proton interactions on different
nuclear targets have been simulated, and the distribution of outgoing particles
has been compared to data. In a second test, penetration of quasi-monoenergetic
low energy neutrons through a thick shielding has been simulated and again
compared to experimental data. In parallel, an effort has been put on the
integration of GEANT4 in the AliRoot framework. An overview of the present
status of ALICE GEANT4 simulation and the remaining problems will be presented.
This document will describe in detail the results of these tests, together with
the improvements that the GEANT4 team has made to the program as a result of
the feedback received from the ALICE collaboration. We will also describe the
remaining problems that have been communicated to GEANT4 but not yet addressed.Comment: 8 pages, 12 figures, for the CHEP03 conference proceeding
Event Reconstruction with MarlinReco at the ILC
After an overview of the modular analysis and reconstruction framework Marlin
an introduction on the functionality of the Marlin-based reconstruction package
MarlinReco is given. This package includes a full set of modules for event
reconstruction based on the Particle Flow approach. The status of the software
is reviewed and recent results using this software package for event
reconstruction are presented.Comment: 6 pages, 2 .eps figures, to appear in Proc. LCWS06, Bangalore, March
200
- …