Nuclear Charge Radius Determination of Iridium Using EUV Spectroscopy of Highly Charged Ions

Author

Adam HosierFollow

Date of Award

12-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics and Astronomy

Committee Chair/Advisor

Dr. Endre Takacs

Committee Member

Dr. Yuri Ralchenko

Committee Member

Dr. Bradley Meyer

Committee Member

Dr. Joan Marler

Abstract

Highly charged ions have emerged on the scene of atomic physics because of their compressed electron cloud enhancing various physical phenomena. While transitions in ions and highly charged ions provide valuable information to different communities, their application in nuclear charge radius measurements becomes increasingly prominent. In this work, we report the extreme ultra-violet spectroscopy of Na-like ions and x-ray spectroscopy of Cu-like, Co-like, and Ni-like ions that explore nuclear charge distributions and the identification of new transitions, respectively.

In the first part of this work, extreme ultra-violet spectroscopy of highly charged ions of Na-like osmium and iridium was performed using a flat-field grazing incidence grating spectrometer. The ground state D1 (3s-3p$_{1/2}$) transition and separation of transitions were measured for both elements in the 4 nm to 20 nm range. Highly accurate atomic structure calculations using Relativistic Many-Body Perturbation Theory (RMBPT) and Multi-Configuration Dirac-Hartree-Fock (MCDHF), including QED and higher-order terms, determined the energy separation of the D1 transitions in both elements and agreed with each other. The discrepancy in the experimentally determined energy separation and theoretically calculated separation is used to extract a correction to an assumed charge radius with an improved uncertainty. The charge radius of $^{191}$Ir was determined to be 5.4307(77) fm, which is an improvement of over an order of magnitude from the currently accepted literature value. The Mg-like charge state was also used in this analysis to achieve this uncertainty level and verify the results as an independent measurement. The uncertainty of all iridium isotopes was reduced because of accurate optical isotope shift measurements. This technique can determine the charge radius of any element created in a Na-like charge state, including trace sample amounts and short-lived radioactive isotopes.

In the second part of this work, new lines in x-ray spectroscopic data of highly charged Nd were observed and measured. The electron beam ion trap at the National Insitute of Standards and Technology created Ni-like and Co-like ions of Nd. The x-ray spectra were recorded with the Transition Edge Sensor Microcalorimeter at NIST. The main features observed were the resonance 3d-4f transitions in Co-like and Ni-like Nd, along with other 3d-$n l$ transitions. Despite being under the ionization potential to create Co-like Nd, a metastable level in Ni-like Nd served as the primary feeding mechanism to populate the Co-like charge state due to the long-lived lifetime of the Ni-like metastable level. 66 new transitions were measured and identified over the energy range of 800 eV to approximately 2000 eV. The identification process was assisted with a non-Maxwellian collisional radiative modeling code NOMAD.

Recommended Citation

Hosier, Adam, "Nuclear Charge Radius Determination of Iridium Using EUV Spectroscopy of Highly Charged Ions" (2023). All Dissertations. 3532.
https://open.clemson.edu/all_dissertations/3532

Author ORCID Identifier

0000-0003-2836-6605