2023 CAP Congress / Congrès de l'ACP 2023

High precision theory for the Rydberg states of helium up to n = 24

21 Jun 2023, 13:45

15m

UNB Tilley Hall (Rm. 5 (max. 70))

Oral not-in-competition (Graduate Student) / Orale non-compétitive (Étudiant(e) du 2e ou 3e cycle) Atomic, Molecular and Optical Physics, Canada / Physique atomique, moléculaire et photonique, Canada (DAMOPC-DPAMPC) (DAMOPC) W2-2 DAMPOC I | DPAMPC I (DPAMPC)

Speaker

Gordon Drake (University of Windsor)

Description

There is a 10$\sigma$ discrepancy between theory and experiment for the ionization energy of the $1s2s^3{S}_1$ state of helium [1]. In order to provide an additional check, Clausen et al. [2] have performed measurements for the Rydberg $P$-states of helium from $n=24$ to $n=100$ and extrapolated to $n=\mathrm{\infty }$ to find the ionization energy. In the present work, we extend previous high-precision variational calculations [3] up to $n=24$ using triple basis sets in Hylleraas coordinates. With the inclusion of relativistic and QED corrections, the results provide a direct theoretical test against the Clausen measurement at $n=24$. The results are in excellent agreement, thereby confirming the 10$\sigma$ discrepancy between theory and experiment for the ionization energy of the $1s2s^3{S}_1$ state of helium.

[1] V. Patkos, V. A. Yerokhin and K. Pachucki, Phys. Rev. A 103, 042809 (2021).

[2] G. Clausen et al. Phys. Rev. Lett. 127, 093001 (2021).

[3] G. W. F. Drake, M. M. Cassar and R. A. Nistor, Phys. Rev. A, 65, 054501 (2002).