The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Myungki Cheoun - One of the best experts on this subject based on the ideXlab platform.
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The effects of density-dependent form factors for (e, e’p) reaction in quasi-Elastic Region
European Physical Journal A, 2016Co-Authors: Myungki Cheoun, W. Y. SoAbstract:Within the framework of a relativistic single particle model, the effects of density-dependent electromagnetic form factors on the exclusive \( (e,e'p)\) reaction are investigated in the quasi-Elastic Region. The density-dependent electromagnetic form factors are generated from a quark-meson coupling model and used to calculate the cross sections in two different densities, either at the normal density of \( \rho_0 \sim 0.15\) fm^-3 or at the lower density, \( 0.5\rho_0\) . Then these cross sections are analyzed in the two different kinematics: One is that the momentum of the outgoing nucleon is along the momentum transfer. The other is that the angle between the momentum of the outgoing nucleon and the momentum transfer is varied at fixed magnitude of the momentum of the outgoing nucleon. Our theoretical differential reduced cross sections are compared with the NIKHEF data for the 208 Pb(e, e’p) reaction, which is related to the probability that a bound nucleon from a given orbit can be knocked-out of the nucleus. The effects of the density-dependent form factors increase the differential cross sections for both knocked-out proton and neutron by an amount of a few percent. Moreover they are shown to be almost the same within only a few percent, i.e., nearly independent of the shell location of knockout nucleons. These results are quite consistent with the characteristics of double magic nuclei which have relatively sharp smearing in the density distribution.
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Effect of Density-Dependent Form Factors on Coulomb Sum Rule in the Quasi-Elastic Region
Journal of the Physical Society of Japan, 2014Co-Authors: Myungki CheounAbstract:Within the framework of a relativistic single particle model, we study the effects of density-dependent electromagnetic form factors on the inclusive (e,e′) reaction in the quasi-Elastic Region. The density-dependent form factors generated by a quark-meson coupling model are applied into the (e,e′) reaction. We calculate the differential cross sections, and extract the longitudinal and transverse structure functions. Furthermore the Coulomb sum is calculated in terms of three momentum transfer from 40Ca. The effects of the density-dependent form factors reduce the longitudinal structure function by amount of a few percent but increase the transverse structure function about 10%, consequently the (e,e′) differential cross sections are enhanced.
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Possible Uncertainties of Parity Violation in Electron Quasi-Elastic Scattering
Journal of the Physical Society of Japan, 2013Co-Authors: Myungki CheounAbstract:From the leading order of the interference of the electromagnetic current and the electroweak neutral current, parity violating electron scattering on a nucleus in the quasi-Elastic Region is investigated by using a relativistic single particle model. We use 208Pb as a target nucleus, and the incident electron energy range is exploited up to 1 GeV. We enumerate possible ambiguities from 208Pb by the electromagnetic form factors, the strangeness form factors, the final states interaction, and the Coulomb effects on the parity violation (PV) asymmetry in the inclusive electrons scattering on the quasi-Elastic Region. The effect of nucleon electromagnetic form factors is studied by comparing the standard Sachs form factors and the parameterized form recently adjusted to the world data. The effect of the strangeness in the PV asymmetry is also investigated through the recent results of the strangeness form factors. We separately calculate the asymmetries of longitudinal and transverse response functions. The ...
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Signals for Strange Quark Contributions to the Neutrino (Antineutrino) Scattering in Quasi-Elastic Region
Journal of the Physical Society of Japan, 2009Co-Authors: Myungki CheounAbstract:Strange quark contributions to Elastic neutrino–nucleon scattering and neutrino–nucleus scattering for 12 C target in quasi-Elastic Region are investigated on the incident energy of 500 MeV within the framework of a relativistic single particle model. For the neutrino–nucleus scattering, the effects of final state interaction for the knocked-out nucleon are included by a relativistic optical potential. In the cross sections for neutrino–nucleus scattering we found some cancellations of the strange quark contributions in the knocked-out proton and neutron process. Consequently, the asymmetries between the incident neutrino and antineutrino, which are given by the ratio of neutral current to charged current, and a difference between the asymmetries are shown to be more feasible quantities for the strangeness effects. In order to explicitly display the importance of such cancellations, results of the exclusive reaction 16 O(ν, ν' p ) are additionally presented for detecting the strangeness effects.
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effect of strangeness for neutrino antineutrino scattering in the quasi Elastic Region
Physical Review C, 2008Co-Authors: Myungki Cheoun, Byung Geel YuAbstract:We present the neutral- and charged-current reactions by incident neutrino (antineutrino) scattering on the nucleon and on the {sup 12}C target in the quasi-Elastic Region within the framework of a relativistic single-particle model. The incident energies at 500 MeV and 1 GeV are used for the scattering. Effects of strangeness are studied thoroughly on the cross sections, the ratios between the neutral- and charged-current reactions, and the asymmetries by incident neutrino and antineutrino. We find that there exists some cancellation of the strange quark contributions between the knocked-out protons and neutrons in the neutrino (antineutrino)-nucleus scattering. The effect of strangeness is exhibited more strongly on the asymmetry than on the ratio or cross section. On a difference of the asymmetry, the effect of strangeness appears strongly, but on a summation of the asymmetry, the effect almost disappears in the low and middle kinetic energies of the knocked-out nucleon.
T G Nieh - One of the best experts on this subject based on the ideXlab platform.
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extended Elastic Region in nanocrystalline hcp and fcc metals under nano tension loading
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: S Y Kuan, J C Huang, Y H Chen, C H Chang, C H Hsieh, J H Wang, Y C Nian, Shinpon Ju, T G NiehAbstract:Abstract Nano-scaled mechanical properties have become important for abundant submicron and nano electronic or mechanical devices. However, the nano-scale mechanical tests have not been developed widely. In this study, a new nano-tension test specimen is designed, using the focused ion beam (FIB) machining. The dimension of the nano-tension gage section can vary from 50 to 1000 nm. The test can be conducted by the widely available nano-indentation facility with a flat tip. The downward applied load from the flat tip onto the central beam (in compression) can be easily transferred to the two-side tension gage sections (in tension). Various pure metals such as face-centered cubic Al and Cu and hexagonal close-packed Mg, Zr, and Ti are selected for the test run. The yield stress and Elastic strain are seen to be exceptionally high. The extended Elastic Region is carefully examined by reproducible experiments and molecule dynamic simulation. It is not considered to be an artifact by FIB machining, but appears to be a common phenomenon for metallic materials in the nano scale when the dislocation activity is difficult to be fully functioned.
Byung Geel Yu - One of the best experts on this subject based on the ideXlab platform.
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effect of strangeness for neutrino antineutrino scattering in the quasi Elastic Region
Physical Review C, 2008Co-Authors: Myungki Cheoun, Byung Geel YuAbstract:We present the neutral- and charged-current reactions by incident neutrino (antineutrino) scattering on the nucleon and on the {sup 12}C target in the quasi-Elastic Region within the framework of a relativistic single-particle model. The incident energies at 500 MeV and 1 GeV are used for the scattering. Effects of strangeness are studied thoroughly on the cross sections, the ratios between the neutral- and charged-current reactions, and the asymmetries by incident neutrino and antineutrino. We find that there exists some cancellation of the strange quark contributions between the knocked-out protons and neutrons in the neutrino (antineutrino)-nucleus scattering. The effect of strangeness is exhibited more strongly on the asymmetry than on the ratio or cross section. On a difference of the asymmetry, the effect of strangeness appears strongly, but on a summation of the asymmetry, the effect almost disappears in the low and middle kinetic energies of the knocked-out nucleon.
Peter K. Liaw - One of the best experts on this subject based on the ideXlab platform.
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Deformation dynamics study of a wrought magnesium alloy by real-time in situ neutron diffraction
Scripta Materialia, 2013Co-Authors: Wei Wu, Soo Yeol Lee, Ke An, Lu Huang, Peter K. LiawAbstract:The deformation dynamics and the effect of deformation history on plastic deformation in a wrought magnesium alloy at room temperature have been studied by real-time in situ neutron diffraction measurements under a continuous loading condition. The experimental results reveal that no detwinning occurred during unloading after compression and even in an Elastic Region during reverse tension. It is found that the serration behavior is closely related to the twinning- and detwinning-dominated deformation. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Yuji C Sasaki - One of the best experts on this subject based on the ideXlab platform.
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shock induced intermediate range structural change of sio2 glass in the nonlinear Elastic Region
Applied Physics Letters, 2012Co-Authors: Kouhei Ichiyanagi, Nobuaki Kawai, Shunsuke Nozawa, Takahiro Sato, Ayana Tomita, Manabu Hoshino, Kentaro Nakamura, Shinichi Adachi, Yuji C SasakiAbstract:We study shock compressed fused quartz in the nonlinear Elastic Region using single-shot time-resolved x-ray scattering measurements. The first sharp diffraction peak (FSDP) of fused quartz shifts to the high Q Region under shock compression. In contrast, the short-range order structure does not change around 3.5 GPa. The nanosecond FSDP shift provides clear evidence of intermediate-range order structural changes in the nonlinear Elastic Region. Because the intermediate-order structure is too short to produce the final structural state in the nonlinear Elastic Region, the FSDP shift is lower compared with hydrostatic experiments.