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A radioactive beam of 20Na is stopped in a gas cell filled with Ne gas. The stopped particles are polarized by optical pumping. The degree of polarization that can be achieved is studied. A maximum polarization of 50% was found. The dynamic processes in the cell are described with a phenomenological model., 16 pages, 6 figures

The lifetime of the long-lived 5d(2)D(5/2) level in Ba-138(+) ions was measured in trapped single ions and small ion crystals using continuous quantum jump spectroscopy. We find tau(D5/2) = 25.6(0.5) s, significantly below previously reported values. We have verified our result by exploiting camera images of the stored ions, which enabled monitoring the cleanliness and sufficiently low temperature of the ion samples, and investigating common systematic effects.

The Ba+ ion, has a structure of spectral lines similar to heavy single valence electron alkali atoms. It is precisely studied by laser spectroscopy in presence of several light fields in order to prepare for a measurement of atomic parity violation (APV). Measurements in heavy alkali earth ions (e.g. Ba+ and Ra+) permit the precise determination of the weak mixing (Weinberg) angle sin2θW with improvement over the previous best measurement in neutral Cs by a factor of 5 in a week of actual measurement time. The transition frequencies for the 6s2S1/2 - 6p2P1/2, 6p2P1/2 - 5d2D3/2 and 6s2S1/2 - 5d2D3/2 transitions in 138Ba+ have been measured to 10−10 relative accuracy employing a line shape model for single ions in a radio frequency Paul trap [1]. These measurements have been extended to 134,136Ba+. Together with a determination of the lifetime of the excited 5d2D5/2 state these measurements provide for a stringent test of calculations, the accuracy of which is pivotal for a determination of sin2θW. The observed lifetime is 25.8(5)s. Being about 5s shorter than previous measurements and calculations agreeing with them, it provides for a puzzle. [1] E. A. Dijck et al., Phy. Rev. A 91, 060501(R)(2015)

Low energy precision measurements provide for precise testing of the Standard Model, e.g., in searches for violations of the discrete symmetries charge conjugation (C), parity (P), and time reversal (T) as well as their combinations CP and CPT. We focus here on new experiments concerning atomic parity violation (APV) and searches for a permanent electric dipole moment (EDM) in atoms. In particular, we address precision APV experiments on Ba+ and Ra+ single ions that will enable the extraction of the Weinberg angle at lowest presently accessible momentum transfer. They are expected to contribute towards searches for new particles such as dark Z-bosons. We also review experimental programmes in which an EDM is searched for and we compare them in a common framework. We describe latest EDM searches in heavy effective two-electron atoms such as Xe and Hg. We also indicate possible future prospects of searches for a permanent EDM of the electron using molecules with large enhancement factors.

We perform precision spectroscopy on Ba+ ions and precisely determine the 6s2S1/2 - 6p2P1/2, 6p2P1/2 - 5d2D3/2, 6s2S1/2 - 5d2D5/2 transition frequencies. We have achieved more than 100 times improved values using single trapped ion and frequency comb and I2 line locked laser system. We have reached 10−11 relative accuracy, where these values test precisely the atomic wave functions. This is important input for a measurement of atomic parity violation in the alkaline earth atoms.

A single Ra+ ion stored in a Paul radio frequency ion trap has excellent potential for a precision measurement of the electroweak mixing angle at low momentum transfer and as the most stable optical clock. The effective transport and cooling of singly charged ions of the isotopes Ra-209 to Ra-214 in a gas filled radio frequency quadrupole device is reported. The absolute frequencies of the transition 7s(2)S(1/)2-7d(2)D(3/2) at wavelength 828 nm have been determined in Ra-212-214(+) with ≤19 MHz uncertainty using laser spectroscopy on small samples of ions trapped in a linear Paul trap at the online facility Trapped Radioactive Isotopes: µicrolaboratories for fundamental Physics (TRIµP) of the Kernfysisch Versneller Instituut.

A single trapped Ra + (Z = 88) ion provides a very promising route towards a most precise measurement of Atomic Parity Violation (APV), since APV effects grow faster than Z 3. This experiment promises the best determination of the electroweak coupling constant at the lowest accessible energies. Such a measurement provides a sensitive test of the Standard Model in particle physics. At the present stage of the experiment, we focus on trapping and laser cooling stable Ba + ions as a precursor for radioactive Ra + . Online laser spectroscopy of the isotopes 209 − 214Ra + in a linear Paul trap has provided information on transition wavelengths, fine and hyperfine structures and excited state lifetimes as test of atomic structure calculations. Additionaly, a single trapped Ra + ion could function as a very stable clock.

General relativity and the standard model are invariant under Lorentz transformations. Lorentz invariance violation is one manifestation of $C\phantom{\rule{0}{0ex}}P\phantom{\rule{0}{0ex}}T$ violation. Weak interactions violate discrete symmetries ($C$, $P$, $C\phantom{\rule{0}{0ex}}P$, and $T$) suggesting searches for violation of $C\phantom{\rule{0}{0ex}}P\phantom{\rule{0}{0ex}}T$ and Lorentz invariance in weak interactions such as ${}^{20}$Na ${\ensuremath{\beta}}^{+}$ decay. This search for a dependence of the ${}^{20}$Na lifetime on the nuclear spin direction improves the limit on sidereal variation in the relative lifetime difference by a factor of 15.

Bloch model, we achieved 0:1 MHz accuracy for the 5d 2 D3/2 { 6p 2 P1/2 and 6s 2 S1/2 { 5d 2 D3/2 transition frequencies, and 0:2 MHz for the 6s 2 S1/2 { 6p 2 P1/2 transition frequency. Trapped single ions can be exploited to investigate the interaction between light and matter, and to construct optical clocks [1]. For these applications based on high precision spectroscopy a good understanding of the optical line shapes involved is indispensable. We have employed an optical frequency comb [2] to measure transition frequencies in Ba + and a model based on optical Bloch equations to extract atomic parameters from uorescence spectra. These are essential ingredients for high precision experiments, in particular for atomic parity violation measurements in single Ba + [3, 4] and Ra + ions [5, 6] in the search for new physics [7]. In this work the frequencies of transitions between three of the lowest ne structure levels in the 138 Ba + ion are addressed. These levels form a -conguration as shown in Fig. 1. The level 6p 2 P1/2 decays to the levels 6s 2 S1/2 and 5d 2 D3/2 with a branching ratio of about 3:1 [8]. We have measured the transition frequencies in a single 138 Ba + ion by driving the transitions 6s 2 S1/2 { 6p 2 P1/2 and 5d 2 D3/2 { 6p 2 P1/2, employing an optical frequency comb as frequency reference. The dynamics of the population of the 2 P1/2 level can be described by optical Bloch equations [9{11]. Coherent coupling between the 2 S1/2 and 2 D3/2 levels is observed when the

The lifetime of the metastable 5d$^2$D$_{5/2}$ state has been measured for a single trapped Ba$^+$ ion in a Paul trap in Ultra High Vacuum (UHV) in the 10$^{-10}$ mbar pressure range. A total of 5046 individual periods when the ion was shelved in this state have been recorded. A preliminary value $\tau_{D_{5/2}} = 26.4(1.7)$~s is obtained through extrapolation to zero residual gas pressure., Comment: 6 pages, 6 figures, EXA 2014

Through precision spectroscopy on Ba+ ions we determine precisely the 6s2S1/2 - 6p2P1/2, 6p2P1/2 - 5d2D3/2, 6s2S1/2 - 5d2D3/2 transition frequencies. In these experiments we employ laser-cooled single trapped ions. The optical frequencies are controlled by a frequency comb and I2 line locked laser system. We have achieved more than 2 orders of magnitude improved values, i.e. we have reached 10−11 relative accuracy. In a further measurement we have determined precisely the lifetime of the lifetime of the 5d2D5/2 state. Our experiment is aimed at precisely testing the available atomic calculations and in particular atomic wave functions the knowledge of which is needed for interpreting a precise measurement of atomic parity violation in heavy alkaline earth atoms through light shifts in the narrow optical 6s2S1/2-5d2D3/2 single photon transition. The weak mixing angle can be determined precisely from the weak interaction contributions between primarily the nuclear neutrons and the atomic valence electron to the atomic binding. Indico - Integrated Digital Conference Powered by Indico GSI Helmholtzzentrum für Schwerionenforschung GmbH | Planckstr. 1 | 64291 Darmstadt | Telefon: +49-6159-71- 0 | Impressum (in German) | Terms of Use