https://hdl.handle.net/1721.1/147645 2026-04-04T14:02:11Z https://hdl.handle.net/1721.1/164953 Estimating Isotope Shifts for $^{227}$Th and $^{229}$Th in Th$^{3+}$: 5F$_{5/2} \rightarrow$ 6D$_{5/2}$ Transition Lam, P. Y. Ian; MohanMurthy, Prajwal \textbf{Motivation:} Accurate spectroscopic information for isotopes of $^{224-232}$Th are critical for experimental programs investigating such thorium isotopes as candidates for next-generation nuclear optical clocks and as platforms for searches of symmetry-violating effects. Direct experimental data on isotope shifts in the $\text{Th}^{3+}:5F_{5/2} \to 6D_{5/2}$ line at $690$ nm are sparse, with measurements available only for $^{229}\text{Th}$ and $^{230}\text{Th}$ relative to the reference isotope $^{232}\text{Th}$.\\ \textbf{Method:} To address this gap, we employed a King-plot analysis comparing the well-characterized isotope shifts of the $\text{Th}^{+}$ transition at $583.9$ nm to the limited data available for the $690$ nm transition of $\text{Th}^{3+}$. Using nuclear structure information on mean-square charge radii and nuclear quadrupole deformations, we extracted the field-shift constant $F_{690}$ and mass-shift constant $M_{690}$ for the $690$ nm transition. We subsequently calculated the missing isotope shifts by incorporating published values of $\delta\langle r^2\rangle$ where available and estimating $\delta\langle r^2\rangle$ for unmeasured isotopes using nuclear quadrupole deformation coefficients $\beta_2$ from the FRDM model.\\ \textbf{Key Results:} The calculated isotope shifts for the $\text{Th}^{3+}:5F_{5/2} \to 6D_{5/2}$ transition relative to $690~$nm transition of $^{232}\text{Th}$ are: \begin{align} \delta\nu^{224,232}_{690} &= -29296(5585) \text{MHz} \nonumber\\ \delta\nu^{225,232}_{690} &= -25840(4930) \text{MHz} \nonumber\\ \delta\nu^{226,232}_{690} &= -22113(4219) \text{MHz} \nonumber\\ \delta\nu^{227,232}_{690} &= -18631(6238) \text{MHz} \nonumber\\ \delta\nu^{228,232}_{690} &= -14970(6181) \text{MHz} \nonumber\\ \delta\nu^{231,232}_{690} &= -3742(715) \nonumber\text{MHz} \end{align} Our results for the isotopes of $^{227,228}$Th use experimental $\delta\langle r^2\rangle$ values, whereas the remaining ones use theoretical values of $\delta\langle r^2\rangle$ calculated from quadrupole deformation coefficients. These results provide essential spectroscopic data for future precision measurements with thorium isotopes in various ionized states. This work is supported by BNL award #460913, a Phi Kappa Phi Fellowship, and generous support from Prof. R. P. Redwine and MIT LNS. 2026-02-25T00:00:00Z https://hdl.handle.net/1721.1/147646 Identifying ideal nuclei in which to search for CP violating moments: Necessity to populate nuclear levels and characterize their nuclear deformation Mohanmurthy, Prajwal; Winger, Jeff New sources of CP violation, beyond the known sources in the standard model (SM) via the CKM matrix, are required to explain the baryon asymmetry of the universe. Measurement of P,T violating moments, such as the electric dipole moment (EDM) or the magnetic quadrupole moment (MQM), of sub-atomic particles like the neutron or the electron as well as of atoms, serves as powerful tools with which to probe sources of CP violation. Quadrupole and octupole deformation of nuclei can significantly enhance the atomic EDM by many orders of magnitude compared to that with a spherical nucleus. In this white paper, we identify deformed isotopes in which to measure an EDM or an MQM. Furthermore, we also clearly identify a subset of these isotopes where measurements involving characterization of their level scheme and nuclear deformation parameters are necessary. (A section in the low energy white paper of the 2022 NSAC Long Range Planning exercise.) 2023-01-24T00:00:00Z