Bulletin of the American Physical Society
Annual Meeting of the APS Four Corners Section
Volume 60, Number 11
Friday–Saturday, October 16–17, 2015; Tempe, Arizona
Session I1: Atomic, Molecular and Optical Physics IV |
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Chair: Daniel Stick, Sandia National Laboratories Room: PSH150 |
Saturday, October 17, 2015 11:00AM - 11:24AM |
I1.00001: \textbf{Spectroscopic studies of Th-containing molecules relevant to physics and chemistry} Invited Speaker: Timothy Steimle \textbf{ThO[1]: }The current upper limit for the magnitude of the electron electric dipole moment (eEDM), $\left| {\mbox{d}_{e} } \right|$, is 8.7\texttimes 10$^{\mathrm{-29}}$ e$\cdot $cm and has been determined in an experiment involving the$\mbox{H}{ }^{3}\Delta_{1} (\mbox{v}=0)$ state of thorium oxide, ThO [2]. An improved determination of the upper limit for $\left| {\mbox{d}_{e} } \right|$ would be an effective route for assessing extensions to the Standard Model; many such extensions predict a $\left| {\mbox{d}_{e} } \right|$of approximately 10$^{\mathrm{-29}}$ e$\cdot $cm. Here we will report on the spectroscopic characterization of an electronic transition that will be used in a new optical pumping and detection schemes to search for $\left| {\mbox{d}_{e} } \right|$. \textbf{Th}$_{\mathrm{\mathbf{2}}}$\textbf{[3]: }Understanding the chemistry of the early to middle actinide elements (Th-Cm) is critical to the nuclear energy industry for the development of efficient enrichment methods as well as methods for waste remediation. Given the hazards of dealing with these elements, computational chemistry is often used to predict their properties. Such predictions can only be tested by comparison with experimental data available for small gas-phase, Th-containing molecules. Bonding in Th$_{\mathrm{2}}$, and other actinides dimers, has been theoretically investigated using multiconfiguration wave function based methods (CASSCF/CASPT2) [4] to predict twelve electronic states all within 1 eV of the ground state. These 12 states give rise to 29 spin-orbit components. Here we report on the first observation of resonant transitions of thorium dimer, Th$_{\mathrm{2}}$, and evaluate the theoretical predictions. \textbf{ThS[5]:} Thorium monosulfide (ThS) is an ideal model system for studies of the interactions between an actinide and a soft donor ligand. Here we report on the results of a separated field, pump/probe microwave optical double resonance measurement of the pure rotational transitions of Th$^{\mathrm{32}}$S $X^{\mathrm{1}}\Sigma^{\mathrm{+}}$. This is the first example of a microwave study of an actinide compound that is not an oxide. The versatility and precision of the spectroscopic method will be outlined. \begin{enumerate} \item Supported by the Chemistry Division of National Science Foundation: CHE-1265885 \end{enumerate} \textbf{References } \begin{enumerate} \item Kokkin, Damian L.; Steimle, Timothy C.; DeMille, David Phys. \textit{Rev. A: At., Mol., and Opt. Phys.~}(2015),~91(4-A),~1-5. ~ \item J. Baron, et al. \textit{Science} (2014),343, 269. \item Steimle, T.; Kokkin, D. L.; Muscarella, S.; Ma, T. \textit{JPCA} 2015,~\textit{119}, 9281-9285. \item Roos, B.; Borin, A. C.; Gagliardi, L. \textit{J. Am. Chem. Soc.} 2006, \textit{128}, 17000-17006. \item Steimle, T.; Zhang R..; Heaven, M. \textit{Chem. Phys. Lett.} (submitted). \end{enumerate} [Preview Abstract] |
Saturday, October 17, 2015 11:24AM - 11:36AM |
I1.00002: A First Look at Laser-cooling Ions in an Ultra-cold Neutral Plasma Kade Bishop, Scott Bergeson We discuss progress in laser-cooling ions in an ultra-cold neutral plasma. A major challenge to implementing a laser-cooling scheme is that the laser-cooling transition is not closed. A fraction of the ions decay into "dark" metastable states and are lost to the cooling process. We have built a system using two infrared diode lasers to optically pump atoms out of the metastable states. The optical pumping transitions form a $\lambda $-system. Avoiding atomic coherences associated with this configuration may be necessary to achieve maximum laser cooling. We describe our laser system and its use in cooling calcium ions in our ultra-cold neutral plasma. We report on the increased efficiency of ion-cooling through repumping into the cooling transition. [Preview Abstract] |
Saturday, October 17, 2015 11:36AM - 11:48AM |
I1.00003: Lyman-alpha Source for Laser Cooling Anti-Hydrogen Cory Rasor Measuring the 1s $\rightarrow$ 2s transition frequency in the anti-hydrogen atom will give insight into the behavior of anti-matter during interactions with light. The necessary spectroscopy to perform such a measurement must be done near the recoil limit of the atom in order to minimize uncertainties. Creating a laser source to conduct the required cooling at the Lyman-$\alpha$ wavelength, 121.57nm, is the focus of my talk. This source is generated by starting with a Titanium Sapphire laser tuned at 730nm, then is frequency doubled using an LBO crystal with proper phase matching, and finally frequency tripled using a mixture of Krypton and Argon gas. We currently project about 100nJ of energy per 10ns pulse. [Preview Abstract] |
Saturday, October 17, 2015 11:48AM - 12:00PM |
I1.00004: Magnetometry for the JILA Electron Electric Dipole Moment Experiment Yiqi Ni, William Cairncross, Kevin Cossel, Matt Grau, Daniel Gresh, Yan Zhou, Jun Ye, Eric Cornell A non-zero permanent electric dipole moment of the electron (eEDM) would violate parity and time-reversal symmetries. The JILA experiment uses the metastable $^3\Delta_1$ state in trapped HfF$^+$ ions to obtain high eEDM measurement sensitivity. We perform an electron spin resonance experiment in the presence of rotating bias electric and magnetic fields. A non-zero eEDM causes a relative energy shift between Zeeman sub-levels. However, the drift of lab magnetic fields is a potential source of additional systematic energy shifts. To actively monitor and compensate these magnetic field drifts, we have calibrated a number of magnetometers and placed them outside of the ion trap. Additionally, an accurately measured lab magnetic field will allow us to isolate and understand other sources of systematic errors. Here, we will discuss the design, construction, and calibration of the magnetometer cluster and its implications for improving the eEDM measurement. [Preview Abstract] |
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