The current status of the Geant4 toolkit and the recent developments for the geometry, electromagnetic and hadronic physics for medium and high energy are presented. The focus of many recent ...improvements of the toolkit are key applications including the simulation of large Hadron collider (LHC) experiments at CERN. These developments and physics model extensions provide new capabilities and improvements for other applications of the toolkit for radiation studies in high energy physics (HEP), space and medical research.
The software tools developed for the validation and verification of the standard electromagnetic physics package of Geant4 are described. The validation is being performed versus experimental data ...and in regression to a previous version of Geant4. Examples of validation results are presented.
An overview of the current status of electromagnetic physics (EM) of the Geant4 toolkit is presented. Recent improvements are focused on the performance of large scale production for LHC and on the ...precision of simulation results over a wide energy range. Significant efforts have been made to improve the accuracy without compromising of CPU speed for EM particle transport. New biasing options have been introduced, which are applicable to any EM process. These include algorithms to enhance and suppress processes, force interactions or splitting of secondary particles. It is shown that the performance of the EM sub-package is improved. We will report extensions of the testing suite allowing high statistics validation of EM physics. It includes validation of multiple scattering, bremsstrahlung and other models. Cross checks between standard and low-energy EM models have been performed using evaluated data libraries and reference benchmark results.
In this work we report on recent improvements in the electromagnetic (EM) physics models of Geant4 and new validations of EM physics. Improvements have been made in models of the photoelectric ...effect, Compton scattering, gamma conversion to electron and muon pairs, fluctuations of energy loss, multiple scattering, synchrotron radiation, and high energy positron annihilation. The results of these developments are included in the new Geant4 version 10.1 and in patches to previous versions 9.6 and 10.0 that are planned to be used for production for run-2 at LHC. The Geant4 validation suite for EM physics has been extended and new validation results are shown in this work. In particular, the effect of gamma-nuclear interactions on EM shower shape at LHC energies is discussed.
Geant4 and Fano cavity test: where are we? Elles, S; Ivanchenko, V N; Maire, M ...
Journal of physics. Conference series,
02/2008, Letnik:
102, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The electron transport algorithm implemented in Geant4 has been recently revised. The modifications concern several physics aspects of the simulation model: the step limitation, the energy loss along ...a step and the multiple scattering. The Fano cavity setup was used to test these developments. The upgrades increase significantly the accuracy of the electron transport simulation. The ratio of simulated to theoretical dose deposition in the cavity is stable to ∼1% while varying several parameters and within ∼1.5% of the expected value for water and graphite. Work is underway to identify and resolve the remaining shift.
Current status of the Standard electro-magnetic (EM) package of the Geant4 toolkit is described. We report on the stability of results with respect to variation of production threshold and Physics ...List. This illustrates the trade between CPU time and precision of simulation predictions. New comparisons of the Geant4 simulation with the experimental data are shown. The CPU benchmark results are discussed.
A
bstract
The cross-sections of exclusive (coherent) photoproduction
J/ψ
and
ψ
(2S) mesons in ultra-peripheral PbPb collisions at a nucleon-nucleon centre-of-mass energy of 5
.
02 TeV are measured ...using a data sample corresponding to an integrated luminosity of 228 ± 10 μb
−
1
, collected by the LHCb experiment in 2018. The differential cross-sections are measured separately as a function of transverse momentum and rapidity in the nucleus-nucleus centre-of-mass frame for
J/ψ
and
ψ
(2S) mesons. The integrated cross-sections are measured to be
σ
J
/
ψ
coh
= 5
.
965
±
0
.
059
±
0
.
232
±
0
.
262 mb and
σ
ψ
2
S
coh
= 0
.
923
±
0
.
086
±
0
.
028
±
0
.
040 mb, where the first listed uncertainty is statistical, the second systematic and the third due to the luminosity determination. The cross-section ratio is measured to be
σ
ψ
2
S
coh
/
σ
J
/
ψ
coh
= 0
.
155
±
0
.
014
±
0
.
003, where the first uncertainty is statistical and the second is systematic. These results are compatible with theoretical predictions.
A
bstract
The CKM angle
γ
is determined from
CP
-violating observables measured in
B
±
→
D
K
∓
π
±
π
±
π
∓
h
±
, (
h
=
K, π
) decays, where the measurements are performed in bins of the decay ...phase-space of the
D
meson. Using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7
,
8 and 13 TeV, corresponding to a total integrated luminosity of 9 fb
−
1
,
γ
is determined to be
γ
=
54.8
+
6.0
−
5.8
+
0.6
−
0.6
+
6.7
−
4.3
∘
,
where the first uncertainty is statistical, the second systematic and the third from the external inputs on the coherence factors and strong phases of the
D
-meson decays.
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