We report a measurement of the radium ion's $7p\phantom{\rule{0.16em}{0ex}}^{2}P_{3/2}$ state branching fractions and improved theoretical calculations. With a single laser-cooled ${}^{226}{\mathrm{Ra}}^{+}$ ion we measure the ${P}_{3/2}$ branching fractions to the $7s\phantom{\rule{0.16em}{0ex}}^{2}S_{1/2}$ ground state $0.876\phantom{\rule{0.16em}{0ex}}78(20)$, the $6d\phantom{\rule{0.16em}{0ex}}^{2}D_{5/2}$ state $0.107\phantom{\rule{0.16em}{0ex}}59(10)$, and the $6d\phantom{\rule{0.16em}{0ex}}^{2}D_{3/2}$ state $0.015\phantom{\rule{0.16em}{0ex}}63(21)$.
We report a measurement of the radium ion's 7p2P3/2 state branching fractions and improved theoretical calculations. With a single laser-cooled 226Ra+ ion we measure the P3/2 branching fractions to the 7s2S1/2 ground state 0.87678(20), the 6d2D5/2 state 0.10759(10), and the 6d2D3/2 state 0.01563(21).
We report the first driving of the $7s{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}\ensuremath{\rightarrow}6d{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{3/2}$ and $7s{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}\ensuremath{\rightarrow}6d{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{5/2}$ electric quadrupole (E2) transitions in Ra+. We measure the frequencies of both E2 transitions and two other low-lying transitions in 226Ra+ that are important for controlling the radium ion's motional and internal states: $6d{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{3/2}\ensuremath{\rightarrow}7p{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{3/2}^{o}$ and $6d{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{5/2}\ensuremath{\rightarrow}7p{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{3/2}^{o}$.
Measurement of 7p2P1/2o branching fractions with laser-cooled 226Ra+
The unstable radium nucleus is appealing for probing new physics due to its high mass, octupole deformation and energy level structure. Ion traps, with long hold times and low particle numbers, are excellent for work with radioactive species, such as radium and radium-based molecular ions, where low activity, and hence low total numbers, is desirable. We address the challenges associated with the lack of stable isotopes in a table-top experiment with a low-activity (∼10μCi) source where we laser-cool radium ions to form radium Wigner crystals. With a laser-cooled radium ion we measured the 7p2P1/2o state's branching fractions to the ground state, 7s2S1/2, and a metastable excited state, 6d2D3/2, to be p=0.9104(7) and 0.0896(7), respectively. With a nearby tellurium reference line we measured the 7s2S1/2→7p2P1/2o transition frequency, 640.09663(6) THz.
Branching fractions for decays from the P3/2 level in 138Ba+ have been measured with a single laser-cooled ion. Decay probabilities to S1/2, D3/2, and D5/2 are determined to be 0.741716(71), 0.028031(23), and 0.230253(61), respectively, which are an order-of-magnitude improvement over previous results. Our methodology only involves optical pumping and state detection, and is hence relatively free of systematic effects. Measurements are carried out in two different ways to check for consistency. Our analysis also includes a measurement of the D5/2 lifetime, for which we obtain 30.14(40) s.
In this work, we carry out experimental measurements and theoretical calculations of the branching fractions for the 4P3/2 state of 40Ca+. The measurements are based on counting photon numbers emitted from hundreds of ions trapped in a linear Paul trap, as their being affected by lasers. The calculations are performed using the relativistic coupled-cluster method at different approximations. The measured values for the decays of the 4P3/2 state into the 4S1/2, 3D5/2, and 3D3/2 states are, respectively, 0.9350(4), 0.0587(4), and 0.0063(2), which agree well with our recommended theoretical values 0.9344(13), 0.0590(12), and 0.0066(1). Our measured values are also consistent with the experimental values of Gerritsma et al. [R. Gerritsma, G. Kirchmair, F. Z\"ahringer, J. Benhelm, R. Blatt, and C. F. Roos, Eur. Phys. J. D 50, 13 (2008)] using a completely different method. Furthermore, we also calculate the branching fractions of the 4P1/2 state using the same method, and compare to the available experimental and theoretical data.
The unstable radium nucleus is appealing for probing new physics due to its high mass, octupole deformation, and energy level structure. Ion traps, with long hold times and low particle numbers, are excellent for work with radioactive species, such as radium and radium-based molecular ions, where low activity, and hence low total numbers, is desirable. We address the challenges associated with the lack of stable isotopes in a tabletop experiment with a low-activity (∼10 μCi) source where we laser-cool trapped radium ions. With a laser-cooled radium ion we measured the 7p^{2}P_{1/2}^{o} state's branching fractions to the ground state, 7s^{2}S_{1/2}, and a metastable excited state, 6d^{2}D_{3/2}, to be p=0.9104(7) and 0.0896(7), respectively. With a nearby tellurium reference line we measured the 7s^{2}S_{1/2}→7p^{2}P_{1/2}^{o} transition frequency, 640.096 63(6) THz.
We present a measurement of the branching fractions for decay from the long-lived 5D5/2 level in 138Ba+. The branching fraction for decay into the 6S1/2 ground state was found to be 0.846(25)stat(4)sys. We also report an improved measurement of the 5D5/2 lifetime, ${\ensuremath{\tau}}_{5{D}_{5/2}}=31.2(0.9)$ s. Together these measurements provide an experimental determination of transition rates for decay out of the 5D5/2 level. The low ($<7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}$ Torr) pressure in the ion trap in which these measurements were made simplified data acquisition and analysis. Comparison of the experimental results with theoretical predictions of the transition rates shows good agreement.