Papers - IGARASHI Akinori
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Cross Section Calculation of H-He Collisions using Three-Electron Close-Coupling Method Reviewed
Akinori and Daiji Kato
Few-body systems 66 3 2024.12
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
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Cross sections in He+ +He collision at intermediate energies Reviewed
A. Igarashi and D. Kato
Eur. Phys. J. D 78 79 2024.6
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
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Two-center and path interference in dissociative capture in p+ H2 collisions Reviewed International coauthorship
S. Bastola, M. Dhital, B. Lamichhane, A. Silvus,R. Lomsadze, A. Hasan, A. Igarashi, and M. Schulz
Physical Review A 109 012821 2024.1
Language：English Publishing type：Research paper (scientific journal)
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Projectile angular distributions in He+ + H collisions Reviewed
A. Igarashi and D. Kato
Physica Scripta 99 015404 2023.12
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
Wehave calculated the differential cross sections for the elastic, excitation toH(n=2), and electrontransfer
processes in He++Hcollision using a semiclassical atomic-orbital close-coupling method within two-electron treatment. The calculations have been implemented with four different basis sets to see the effects of electron-exchange, electron-transfer channels, and continuum channels. The results are compared with those of experiments and other calculations. -
Cross sections in H+ +He collision at intermediate energies Reviewed
A. Igarashi and D. Kato
The European Physical Journal D 77 190 2023.10
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
An atomic-orbital close-coupling method is applied to H++He collisions for collision energies 1–
200 keV. We show the cross sections for the elastic scattering, excitation to He(21S) and He(21P), electron
capture to H(2 s) and H(2p), and so on. Depending on the processes, the present results agree with some experiments, but disagree with some. Discrepancies are also found between present results and those of
existent two-electron calculations for electron capture to H(2 s) and excitation to He(21S) and He(21P) below 20 keV. -
Cross sections in He++H collisions for the energy region 1-100 keVu-1 Reviewed
A Igarashi and D Kato
Physica Scripta 98 ( 055402 ) 2023.4
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
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Igarashi A., Kato D.
Physica Scripta 98 ( 4 ) 2023.3
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Physica Scripta
The collisions between proton and helium are treated with a semi-classical atomic orbital expansion for proton incident energies 5-150 keV considering two-electrons explicitly. Differential cross sections with respect to the projectile scattering angle are calculated for elastic scattering, 21S and 21P excitation, single electron capture, and single ionization. The agreement with experiments are mostly good, but non-negligible discrepancies are seen for the elastic scattering and the single electron capture with target excitation.
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Fully differential investigation of two-center interference in dissociative capture in p + H2 collision Invited Reviewed International coauthorship
S. Bastola, M. Dhital, B. Lamichhane, A. Silvus, R. Lomsadze, J. Davis, A. Hasan, A. Igarashi, and M. Schulz
Phys. Rev. A 105 032805 2022.3
Language：English Publishing type：Research paper (scientific journal)
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イオンと原子・分子の電離及び電荷移行衝突における微分断面積 Reviewed
五十嵐 明則
原子衝突学会誌 しょうとつ 18 ( 5 ) 106 - 117 2021.9
Authorship：Lead author Language：Japanese Publishing type：Research paper (other academic)
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Projectile angular distribution for electron capture in p + H2 collision considering the vibrational motion Reviewed
A Igarashi
Journal of Physics B: Atomic, Molecular and Optical Physics 53 ( 22 ) 225205 2020.10
Language：English Publishing type：Research paper (scientific journal)
We show the results calculated with improved treatment for the interaction between incident proton and nuclei in H2 over our previous work [2019 J. Phys. B: At. Mol. Opt. Phys. 52 075204] for electron capture process from H2 by proton with including the vibrational motion of molecules. Moreover, the differential cross sections with respect to the projectile scattering angle are calculated and the results are compared with experimental data. It is found that the inclusion of vibrational motion of molecules is essential to reproduce the experimental angular distribution for the fixed molecular orientation parallel to the transverse momentum transfer.
DOI： https://iopscience.iop.org/article/10.1088/1361-6455/abbe2a
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Fully differential cross sections for ionization of Li(2s) and Li(2p) by 16 MeV Li2+ impact Reviewed
A Igarashi and L Gulyas
Journal of Physics B: Atomic, Molecular and Optical Physics 53 ( 7 ) 075203 2020.3
Language：English Publishing type：Research paper (scientific journal)
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Effective fully differential cross-section in single ionization of helium by fast ions Reviewed
A Igarashi and L Gulyas
Journal of Physics B: Atomic, Molecular and Optical Physics 52 ( 24 ) 245203 2019.11
Language：English Publishing type：Research paper (scientific journal)
Fully differential measurements for the single ionization of helium by fast ion impacts are discussed by evaluating effective fully differential cross-sections (EFDCSs) proposed by Kouzakov (2017 Eur. Phys. J. D 71 63) where the coherence properties of the projectile and the target beams are taken into account. The present evaluation of the EFDCS is extended by including instrumental uncertainties. The experimental data are compared with theoretical results where the electron emission is described within the framework of the continuum distorted wave with eikonal initial state (CDW-EIS) method. In most cases, the obtained EFDCSs agree with the experimental data better than those evaluated without considering coherence properties and inclusion of experimental uncertainties.
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Vibrationally resolved capture cross section in p + H2 collision Reviewed
A Igarashi and L Gulyas
J. Phys. B: At. Mol. Opt. Phys 52 075204 2019.3
Language：English Publishing type：Research paper (scientific journal)
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Theoretical investigation of the fully differential cross sections for single ionization of He in collisions with 75-keV protons Reviewed
L. Gulyas, S. Egri, and A. Igarashi
Physical review A 99 032704 2019.3
Language：English Publishing type：Research paper (scientific journal)
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Collision Strengths and Effective Collision Strengths for Allowed Transitions among the n < 5 Degenerate Levels of Atomic Hydrogen Reviewed
Kanti M. Aggarwal, Ryu Owada and Akinori Igarashi
Atoms 6 ( 3 ) 37 2018.7
Language：English Publishing type：Research paper (scientific journal)
We report calculations of collision strengths and effective collision strengths for 26 allowed
transitions among the n < 5 degenerate levels of atomic hydrogen for which the close-coupling (CC) and
Born approximations have been used. Results are listed over a wide range of energies (up to 100 Ryd)
and temperatures (up to 107 K), sufficient for applications over a variety of plasmas, including fusion.
Similar results have also been calculated for deuterium, but they negligibly differ with those of hydrogen.DOI： 10.3390/atoms6030037
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Differential cross sections for ionizations of H and H<inf>2</inf>by 75 keV proton impact Reviewed
Igarashi A., Gulyás L.
Journal of Physics B: Atomic, Molecular and Optical Physics 51 ( 3 ) 035201 2018.1
Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Physics B: Atomic, Molecular and Optical Physics
© 2018 IOP Publishing Ltd. We have calculated total, partial and fully differential cross sections (FDCSs) for ionizations of H and H 2 by 75 keV proton impact within the framework of the continuum-distorted-wave-eikonal-initial-state (CDW-EIS) approximation. Applying the single active electron model, the interaction between the projectile and the target ion is taken into account in the impact parameter picture. Extension of the CDW-EIS model to the molecular target is performed using the two-effective center approximation. The obtained results are compared with those of experimental and other theoretical data when available. The agreements between the theories and the experimental data are generally reasonable except for some cases of the FDCSs.
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Differential cross sections for electron capture in p + H<inf>2</inf>collisions Reviewed
Igarashi A., Gulyás L., Ohsaki A.
European Physical Journal D 71 ( 11 ) 2017.11
Language：English Publishing type：Research paper (scientific journal) Publisher：European Physical Journal D
© 2017, EDP Sciences, SIF, Springer-Verlag GmbH Germany, part of Springer Nature. Abstract: Projectile angular distributions for electron capture in p + H 2 collisions at 25 and 75 keV impact energies, measured by Sharma et al. [Phys. Rev. A 86, 022706 (2012)], are calculated using the CDW-EIS and eikonal approximations. Angular distributions evaluated in the CDW-EIS approximation are in good agreement with the experimental data measured for coherent projectile beams. Incoherent projectile scatterings are also considered by folding the coherent angular distributions over the transverse momentum distribution of the projectile wave-packet. Reasonable agreements with the measurements are obtained only with coherence parameters very different from those reported in the experiments. Graphical abstract: [Figure not available: see fulltext.] .
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Radiative Rates and Electron Impact Excitation Rates for Transitions in He II Reviewed
K. M. Aggarwal, A. Igarashi, F. P. Keenan and S. Nakazaki
Atoms 5 ( 2 ) 19 2017.5
Language：English Publishing type：Research paper (scientific journal)
We report calculations of energy levels, radiative rates, collision strengths and effective
collision strengths for transitions among the lowest 25 levels of the n 5 configurations of He II. The
general-purpose relativistic atomic structure package (GRASP) and Dirac atomic R-matrix code (DARC)
are adopted for the calculations. Radiative rates, oscillator strengths and line strengths are reported
for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole
(M2) transitions among the 25 levels. Furthermore, collision strengths and effective collision strengths
are listed for all 300 transitions among the above 25 levels over a wide energy (temperature) range up
to 9 Ryd (105.4 K)DOI： 10.3390/atoms5020019
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Differential cross sections for the single ionization of H2 by 75keV proton impact Reviewed
A Igarashi and L Gulyas
J. Phys. B: At. Mol. Opt. Phys. 50 035201 2017.1
Language：English Publishing type：Research paper (scientific journal)
We have calculated the double and triple differential cross sections for electron ejection with
energy of 14.6 eV in single ionization of H2 by 75 keV proton impact. A molecular version of the
continuum distorted wave-eikonal initial state approach is applied, where the interaction between
the projectile and the residual molecular ion is considered more properly than in previous
applications of the method. For triple differential cross sections, the present results are in better
agreement with the experimental data than those of other descriptions when large momentum
transfer values are considered. For double differential cross sections the experimental data are
reproduced quite well for both coherent and incoherent proton beams. -
Production Ratio for Para- and Ortho-Ps in Photodetachment of Ps#U- Reviewed
A. Igarashi
Few-Body Systtems 58 1 - 5 2016.11
Language：English Publishing type：Research paper (scientific journal)
Para- and ortho-Ps atoms are formed in the photodetachment of positronium negative ion. Since
the lifetime against the pair annihilation is much shorter for para-Ps(ns) than for ortho-Ps(ns), the production
ratio of para- and ortho-Ps atoms is important for the photodetachment experiments.We have derived the ratio
explicitly.