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Register a new userStorage-ring measurement of the hyperfine-induced 2s 2p 3P0 -> 2s2 1S0 transition rate in beryllium-like sulfur
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The hyperfine induced 2s 2p 3P0 -> 2s2 1S0 transition rate in Be-like sulfur was measured by monitoring the decay of isotopically pure beams of 32-S12+ and 33-S12+ ions in a heavy-ion storage ring. Within the 4% experimental uncertainty the experimental value of 0.096(4)/s agrees with the most recent theoretical results of Cheng et al. [Phys. Rev. A 77, 052504 (2008)] and Andersson et al. [Phys. Rev. A 79, 032501 (2009)]. Repeated experiments with different magnetic fields in the storage-ring bending magnets demonstrate that artificial quenching of the 2s 2p 3P0 state by these magnetic fields is negligible.
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We report for the first time, laser spectroscopy of the 1S0 - 3P0 clock transition in 27Al+. A single aluminum ion and a single beryllium ion are simultaneously confined in a linear Paul trap, coupled by their mutual Coulomb repulsion. This coupling allows the beryllium ion to sympathetically cool the aluminum ion, and also enables transfer of the aluminums electronic state to the berylliums hyperfine state, which can be measured with high fidelity. These techniques are applied to a measurement of the clock transition frequency, u = 1 121 015 393 207 851(8) Hz. They are also used to measure the lifetime of the metastable clock state, tau = 20.6 +/- 1.4 s, the ground state 1S0 g-factor, g_S = -0.00079248(14), and the excited state 3P0 g-factor, g_P = -0.00197686(21), in units of the Bohr magneton.
We report the first experimental determination of the hyperfine quenching rate of the $6s^2 ^1!S_0 (F=1/2) - 6s6p ^3!P_0 (F=1/2)$ transition in $^{171}$Yb with nuclear spin $I=1/2$. This rate determines the natural linewidth and the Rabi frequency of the clock transition of a Yb optical frequency standard. Our technique involves spectrally resolved fluorescence decay measurements of the lowest lying $^3!P_{0,1}$ levels of neutral Yb atoms embedded in a solid Ne matrix. The solid Ne provides a simple way to trap a large number of atoms as well as an efficient mechanism for populating $^3!P_0$. The decay rates in solid Ne are modified by medium effects including the index-of-refraction dependence. We find the $^3!P_0$ hyperfine quenching rate to be $(4.42pm0.35)times10^{-2} mathrm{s}^{-1}$ for free $^{171}$Yb, which agrees with recent ab initio calculations.
We measured the absolute frequency of the optical clock transition 1S0 (F = 1/2) - 3P0 (F = 1/2) of 171Yb atoms confined in a one-dimensional optical lattice and it was determined to be 518 295 836 590 863.5(8.1) Hz. The frequency was measured against Terrestrial Time (TT; the SI second on the geoid) by using an optical frequency comb of which the frequency was phase-locked to an H-maser as a flywheel oscillator traceable to TT. The magic wavelength was also measured as 394 798.48(79) GHz. The results are in good agreement with two previous measurements of other institutes within the specified uncertainty of this work.
The hyperfine induced $2s2p ^3P_0, ^3P_2 to 2s^2 ^1S_0$ E1 transition probabilities of Be-like ions were calculated using grasp2K based on multi-configuration Dirac-Fock method and HFST packages. It was found that the hyperfine quenching rates are strongly affected by the interference for low-Z Be-like ions, especially for $2s2p ^3P_0 to 2s^2 ^1S_0$ transition. In particular, the trends of interference effects with atomic number $Z$ in such two transitions are not monotone. The strongest interference effect occurs near Z=7 for $2s2p ^3P_0 to 2s^2 ^1S_0$ E1 transition, and near Z=9 for $2s2p ^3P_2 to 2s^2 ^1S_0$ E1 transition.
Hyperfine induced $1s2s ^1S_0 to 1s^2 ^1S_0$ M1 transition probabilities of He-like ions have been calculated from relativistic configuration interaction wavefunctions including the frequency independent Breit interaction and QED effects. Present results for {$^{151}$}Eu and {$^{155}$}Gd are in good agreement with previous calculations [Phys. Rev. A {bf 63}, 054105 (2001)]. Electronic data are given in terms of a general scaling law in $Z$ that, given isotopic nuclear spin and magnetic moment, allows hyperfine induced decay rates to be estimated for any isotope. The results should be helpful for future experimental investigations on QED and parity non-conservation effects.
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