MODERN PROBLEMS OF NUCLEAR ENERGY AND NUCLEAR TECHNOLOGIES

Target excitation and ionisation in antiproton collisions with He in singlet and triplet states

Not scheduled

20m

Institute of Nuclear Physics

Poster Theoretical and experimental physics

Speaker

Prof. Alisher Kadyrov (Curtin University and Institute of Nuclear Physics Academy of Sciences Republic of Uzbekistan)

Description

Obtaining accurate benchmark data for ion-atom collisions is crucial for a wide range of practical applications. The most important data needed for applications is often the cross sections for various scattering processes. With recent advancements in available computing resources [1], we are able to study these systems with much better accuracy and detail than ever before.

Antiproton collisions with helium atoms have attracted significant interest [2]. However, important data is still missing for these collisions or there is no agreement between various theories. Being one of the simplest problems involving two electrons, it is of utmost importance to have a complete set of accurate benchmark results for all scattering processes that can occur. Furthermore, the helium target can be initially configured in two different electronic spin states, the singlet and triplet states. The total spin is conserved throughout the collision which allows us to investigate the dependence of the scattering cross sections on the initial target spin for the
first time.

A new version of the convergent close-coupling approach to ion-atom collisions using the Coulomb-Sturmian basis (referred to as CS-CCC) is developed and applied to antiproton collisions with He in the singlet and triplet states [3]. We show that a unified treatment of the excitation and ionisation processes [4] can be applied for this system as well. Furthermore, we present the total elastic as well the single-electron ionisation and single-electron excitation cross sections for incident energies between 1 keV and 1 MeV. We find significant disagreement between various calculations of the cross section for excitation of the singlet state of He.

References
[1] I. B. Abdurakhmanov, N. W. Antonio, M. Cytowski, and A. S. Kadyrov, in High Performance Computing, pp 102-114. ISC High Performance 2024 International Workshops. Lecture Notes in Computer Science, Vol. 15058, edited by M. Weiland, S. Neuwirth, C. Kruse, and T. Weinzierl (Springer, Cham, 2025).
[2] T. Kirchner and H. Knudsen, J. Phys. B 44, 122001 (2011).
[3] N. W. Antonio and A. S. Kadyrov, Phys Rev. A 111, 052806 (2025).
[4] N. W. Antonio, I. Bray, and A. S. Kadyrov, Phys. Rev. A 110, 032810 (2024).
[5] A. Igarashi, A. Ohsaki, and S. Nakazaki, Phys. Rev. A 64, 042717 (2001).
[6] M. McGovern, D. Assafrão, J. R. Mohallem, C. T. Whelan, and H. R. J. Walters, Phys. Rev. A 79, 042707 (2009).