Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session C8: GPMFC Prize and Fellowship Session |
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Sponsoring Units: GPMFC Chair: Siu Au Lee, Colorado State University Room: Hyatt Regency Jacksonville Riverfront City Terrace 4 |
Saturday, April 14, 2007 1:30PM - 2:06PM |
C8.00001: Francis M. Pipkin Award: Diatomic molecules: a powerful new tool for tests of fundamental physics Invited Speaker: The complex energy level structure of molecules can be employed to dramatically enhance certain symmetry-violating effects. Our group is developing new techniques for controlling the quantum degrees of freedom (both internal and external) of diatomic molecules, in order to take advantage of these enhancements. Our experiments using molecules explore three different areas of fundamental interest in physics. The first of these is a search for the electron's electric dipole moment, a time-reversal violating effect predicted to appear at an observable level in most extensions to the Standard Model. The second is an improved measurement of the neutral electroweak vector electronic-axial hadronic coupling, complementary to previous and planned deep inelastic scattering measurements. The third is a high-sensitivity search for the possible temporal variation of a fundamental constant of nature, the electron-to-proton mass ratio. This talk will highlight our progress on, and future vision for, these experiments. [Preview Abstract] |
Saturday, April 14, 2007 2:06PM - 2:42PM |
C8.00002: Herbert P. Broida Prize: Stable and Accurate Single-Atom Optical Clocks Invited Speaker: Optical clocks based on narrow transitions of single ions have long promised unprecedented stability and accuracy, but only lately has this potential begun to be realized [1-3]. At NIST, two single-ion optical clocks are in operation. A $^{199}$Hg$^{+}$ clock uses a single laser-cooled ion held in a cryogenic rf Paul trap and is based on the $^{2}$S$_{1/2}$ ($F$ = 0) $\leftrightarrow \quad ^{2}$D$_{5/2}$ ($F$ = 2, $m_{F} = 0)$ electric-quadrupole transition at 282 nm. An $^{27}$Al$^{+}$ clock uses a single ion held in a linear trap and is based on the $^{1}$S$_{0} \quad \leftrightarrow \quad ^{3}$P$_{0}$ intercombination line at 267 nm [4]. The burden of cooling, state preparation and state detection of the Al$^{+}$ ion are borne by an auxiliary Be$^{+}$ ion using quantum logic methods [5]. A recent comparison of these two standards achieved a relative fractional frequency instability of less than 7 $\times $ 10$^{-15 }(\tau $/s)$^{-1/2}$, reaching 4 $\times $ 10$^{-17}$ in 30 000. The absolute frequency of the Hg$^{+}$ clock was measured against the cesium fountain standard NIST-F1, and we obtained fractional frequency inaccuracies below 10$^{-15}$. An evaluation of the systematic shifts of the Hg$^{+}$ system in the latest of these measurements returns a total systematic uncertainty of about 3 x 10$^{-17}$ and that of the Al$^{+}$ standard, 2.6 x 10$^{-17}$. We will report the results of measurements conducted over the course of five years and discuss the implications of these results as a constraint to test for the constancy of the fundamental constants that determine atomic transition frequencies [6]. We will also describe the present limitations and planned improvements to the accuracy of the single ion clocks. 1. H.S. Margolis \textit{et al., }Science \textbf{306}, 1355 (2004). 2. T. Schneider, E. Peik, and Chr. Tamm, Phys. Rev. Lett. \textbf{94}, 230801 (2005). 3. W.H. Oskay \textit{et al.}, Phys. Rev. Lett. \textbf{97}, 020801 (2006). 4. P.O. Schmidt \textit{et al., }Science \textbf{309}, 749 (2005). 5. D.J. Wineland \textit{et al.}, \textit{Proc. 6th Symposium on Frequency Standards and Metrology, }P. Gill, ed. (World Scientific, Singapore, 2002) pp. 361-368. 6. T. M. Fortier \textit{et al.,} Phys. Rev. Lett. accepted for publication (2007). [Preview Abstract] |
Saturday, April 14, 2007 2:42PM - 3:18PM |
C8.00003: Atom Trap, Krypton-81, and Saharan Water Invited Speaker: Since radiocarbon dating was first demonstrated in 1949, the field of trace analyses of long-lived cosmogenic isotopes has seen steady growth in both analytical methods and applicable isotopes. The impact of such analyses has reached a wide range of scientific and technological areas. A new method, named Atom Trap Trace Analysis (ATTA), was developed by our group and used to analyze $^{81}$Kr (t$_{1/2}$ = 2.3$\times $10$^{5}$ years, isotopic abundance $\sim $ 1$\times $10$^{-12})$ in environmental samples. In this method, individual $^{81}$Kr atoms are selectively captured and detected with a laser-based atom trap. $^{81}$Kr is produced by cosmic rays in the upper atmosphere. It is the ideal tracer for dating ice and groundwater in the age range of 10$^{4}$--10$^{6}$ years. As the first real-world application of ATTA, we have determined the mean residence time of the old groundwater in the Nubian Aquifer located underneath the Sahara Desert. Moreover, this method of capturing and probing atoms of rare isotopes is also applied to experiments that study exotic nuclear structure and test fundamental symmetries. This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. [Preview Abstract] |
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