Purpose:
TheGEANT4 general-purpose Monte Carlo simulation toolkit is able to simulate physical interaction processes of electrons, hydrogen and helium atoms with charge states (
H
0
,
H
+
) and (
He
...0
,
He
+
,
He
2
+
), respectively, in liquid water, the main component of biological systems, down to the electron volt regime and the submicrometer scale, providing GEANT4 users with the so-called “GEANT4-DNA” physics models suitable for microdosimetry simulation applications. The corresponding software has been recently re-engineered in order to provide GEANT4 users with a coherent and unique approach to the simulation of electromagnetic interactions within the GEANT4 toolkit framework (since GEANT4 version 9.3 beta). This work presents a quantitative comparison of these physics models with a collection of experimental data in water collected from the literature.
Methods:
An evaluation of the closeness between the total and differential cross section models available in theGEANT4 toolkit for microdosimetry and experimental reference data is performed using a dedicated statistical toolkit that includes the Kolmogorov–Smirnov statistical test. The authors used experimental data acquired in water vapor as direct measurements in the liquid phase are not yet available in the literature. Comparisons with several recommendations are also presented.
Results:
The authors have assessed the compatibility of experimental data withGEANT4 microdosimetry models by means of quantitative methods. The results show that microdosimetric measurements in liquid water are necessary to assess quantitatively the validity of the software implementation for the liquid water phase. Nevertheless, a comparison with existing experimental data in water vapor provides a qualitative appreciation of the plausibility of the simulation models. The existing reference data themselves should undergo a critical interpretation and selection, as some of the series exhibit significant deviations from each other.
Conclusions:
TheGEANT4-DNA physics models available in the GEANT4 toolkit have been compared in this article to available experimental data in the water vapor phase as well as to several published recommendations on the mass stopping power. These models represent a first step in the extension of the GEANT4 Monte Carlo toolkit to the simulation of biological effects of ionizing radiation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of ...polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19 MeV/c, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.
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In a previous study, we compared experimental data of the total and angular differential cross sections of
π
0
photo-production off the proton to theoretical models implemented in version 9.6.p02 of ...the GEANT4 Monte Carlo simulation toolkit (Amar et al. in Eur Phys J A 55:62, 2019). This paper describes a similar work but for the exclusive and differential cross sections of the
π
+
photo-production off the proton. The Chiral Invariant Phase Space (CHIPS) and Bertini Cascade (BERT) models were compared to the experimental data from the CEBAF Large Acceptance Spectrometer (CLAS) of Jefferson Lab and the phenomenological Scattering Analysis Interactive Dial-in (SAID) model. Relativistic Breit–Wigner fits were used to compare the description of the nucleon resonance region up to 3 GeV from SAID, CLAS and CHIPS. As observed in the
π
0
case, the CHIPS model provides a reasonable description of the invariant mass distribution while the limited tabulated data set of the BERT model is not adequate. Furthermore, the
γ
p
→
n
π
+
differential cross sections
d
σ
/
d
Ω
show significant differences between CHIPS and both CLAS and SAID data pointing to some needed improvements in its physics.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The electromagnetic form factors of the proton and neutron encode information on the spatial structure of their charge and magnetization distributions. While measurements of the proton are relatively ...straightforward, the lack of a free neutron target makes measurements of the neutron's electromagnetic structure more challenging and more sensitive to experimental or model-dependent uncertainties. Various experiments have attempted to extract the neutron form factors from scattering from the neutron in deuterium, with different techniques providing different, and sometimes large, systematic uncertainties. We present results from a novel measurement of the neutron magnetic form factor using quasielastic scattering from the mirror nuclei ^{3}H and ^{3}He, where the nuclear effects are larger than for deuterium but expected to largely cancel in the cross-section ratios. We extracted values of the neutron magnetic form factor for low-to-modest momentum transfer, 0.6<Q^{2}<2.9 GeV^{2}, where existing measurements give inconsistent results. The precision and Q^{2} range of these data allow for a better understanding of the current world's data and suggest a path toward further improvement of our overall understanding of the neutron's magnetic form factor.
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We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the ...four-momentum transfer range 0.2
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6.
Neutron-unbound states in Ne 31 Chrisman, D.; Kuchera, A. N.; Baumann, T. ...
Physical review. C,
09/2021, Volume:
104, Issue:
3
Journal Article
Peer reviewed
Open access
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The 9th meeting of the African Society of Human Genetics, in partnership with the Senegalese Cancer Research and Study Group and the Human Heredity and Health in Africa (H3Africa) Consortium, was ...held in Dakar, Senegal. The theme was Strengthening Human Genetics Research in Africa. The 210 delegates came from 21 African countries and from France, Switzerland, UK, UAE, Canada and the USA. The goal was to highlight genetic and genomic science across the African continent with the ultimate goal of improving the health of Africans and those across the globe, and to promote the careers of young African scientists in the field. A session on the sustainability of genomic research in Africa brought to light innovative and practical approaches to supporting research in resource-limited settings and the importance of promoting genetics in academic, research funding, governmental and private sectors. This meeting led to the formation of the Senegalese Society for Human Genetics. Le 9ème congrès de la Société Africaine de Génétique Humaine, en partenariat avec le Groupe d’Etude et de Recherche sur le Cancer (GERC) et le Consortium H3Africa, s’est tenu à Dakar, au Sénégal. Le thème était «Renforcer la recherche en Génétique Humaine en Afrique». Les 210 participants sont venus de 21 pays africains et de six non africains. L’objectif était de valoriser la génétique et la génomique à travers l’Afrique avec comme but ultime d’améliorer la santé des populations, et de promouvoir les carrières des jeunes chercheurs Africains. Une session sur la pérennité de la recherche génomique a révélé des approches innovantes et pratiques supportant la recherche dans des contextes de ressources limitées et l’importance de promouvoir la formation universitaire en génétique, le financement de la recherche par les gouvernements et le privé. Ce congrès conduisit à la création de la Société Sénégalaise de Génétique Humaine.
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The recent discovery and spectroscopic measurements of O 27 and O 28 suggests the disappearance of the N = 20 shell structure in these neutron-rich oxygen isotopes. We measured one- and two-proton ...removal cross sections from F 27 and Ne 29 , respectively, extracting spectroscopic factors and comparing them to shell model overlap functions coupled with eikonal reaction model calculations. The invariant mass technique was used to reconstruct the two-body ( O 24 + n ) and three-body ( O 24 + 2 n ) decay energies from knockout reactions of F 27 (106.2 MeV/u) and Ne 29 (112.8 MeV/u) beams impinging on a Be 9 target. The one-proton removal from F 27 strongly populated the ground state of O 26 and the extracted cross section of 3 . 4 − 1.5 + 0.3 mb agrees with eikonal model calculations that are normalized by the shell model spectroscopic factors and account for the systematic reduction factor observed for single nucleon removal reactions within the models used. For the two-proton removal reaction from Ne 29 an upper limit of 0.08 mb was extracted for populating states in O 27 decaying though the ground state of O 26 . The measured upper limit for the population of the ground state of O 26 in the two-proton removal reaction from Ne 29 indicates a significant difference in the underlying nuclear structure of F 27 and Ne 29 . Published by the American Physical Society 2024
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