Dvofotonski raspad stanja sličnih 1s2s 1S0 u teškim atomskim sustavima

In He-like systems the direct decay of the 1s2s 1S0 state to the 1s2 1S0 ground state is "forbidden". The transition 1s2s 1S0® 1s2 1S0 by two photons sensitively probes the structure of the complete atomic system. In particular, the shape of the two-photon spectrum is sensitive to it and also reveals for heavy atomic numbers details of relativistic effects in strong central fields. A brief survey on this field of research is given with special emphasis on high nuclear charge Z.U sustavima sličnim He je izravan raspad stanja 1s2s 1S0 u osnovno stanje 1s2 1S0 “zabranjen”. Prijelaz 1s2s 1S0 → 1s2 1S0 emisijom dvaju fotona je osjetljiva proba strukture cijelog atomskog sustava. Oblik dvofotonskog spektra je posebno osjetljiv i otkriva detalje relativističkih učinaka u jakim središnjim poljima teških atoma. Daje se kratak pregled ovog polja s posebnim naglaskom na sustave visokog Z

Dvofotonski raspad stanja sličnih 1s2s 1S0 u teškim atomskim sustavima

In He-like systems the direct decay of the 1s2s 1S0 state to the 1s2 1S0 ground state is "forbidden". The transition 1s2s 1S0® 1s2 1S0 by two photons sensitively probes the structure of the complete atomic system. In particular, the shape of the two-photon spectrum is sensitive to it and also reveals for heavy atomic numbers details of relativistic effects in strong central fields. A brief survey on this field of research is given with special emphasis on high nuclear charge Z.U sustavima sličnim He je izravan raspad stanja 1s2s 1S0 u osnovno stanje 1s2 1S0 “zabranjen”. Prijelaz 1s2s 1S0 → 1s2 1S0 emisijom dvaju fotona je osjetljiva proba strukture cijelog atomskog sustava. Oblik dvofotonskog spektra je posebno osjetljiv i otkriva detalje relativističkih učinaka u jakim središnjim poljima teških atoma. Daje se kratak pregled ovog polja s posebnim naglaskom na sustave visokog Z

Single Transfer-Excitation Resonance Observed Via the Two-Photon Decay in He-like Ge³⁰⁺

We measured the 2E1 decay of the 1s2s 1S0 →1s2 1S0 transition in He-like germanium for 12- to 19-MeV/u Ge31+ +H2 collisions. The resonant population of the 2s2p 1P1 state by transfer excitation was isolated due to its cascading to the 1s2s 1S0 state. The experimental cross sections compare well with calculations using dielectronic recombination rates. The method gives the unique possibility to populate selectively the 1S0 state in heavy He-like ions

On the Transition Rate of the Fe X RED Coronal Line

We present a lifetime measurement of the 3s 23p 5 2 Po 1/2 first excited fine-structure level of the ground state configuration in chlorine-like Fe X, which relaxes to the ground state through a magnetic dipole (M1) transition (the so-called red coronal line) with a wavelength accurately determined to 637.454(1) nm. Moreover, the Zeeman splitting of line was observed. The lifetime of 14.2(2) ms is the most precise one measured in the red wavelength region and agrees well with advanced theoretical predictions and an empirically scaled interpolation based on experimental values from the same isoelectronic sequence

Isotope Shift in the Dielectronic Recombination of Three-electron \u3csup\u3eA\u3c/sup\u3eNd⁵⁷⁺

Isotope shifts in dielectronic recombination spectra were studied for Li-like ANd57+ ions with A = 142 and A = 150. From the displacement of resonance positions energy shifts δE142 150(2s-2p1/2) = 40.2(3)(6) meV [(stat)(sys)] and δE142 150(2s - 2p3/2) = 42.3(12)(20)meV of 2s - 2pj transitions were deduced. An evaluation of these values within a full QED treatment yields a change in the mean-square charge radius of 142 150δ⟨ r2⟩ = -1.36(1)(3) fm2. The approach is conceptually new and combines the advantage of a simple atomic structure with high sensitivity to nuclear size

Searching for stochastic gravitational waves using data from the two colocated LIGO Hanford detectors

Searches for a stochastic gravitational-wave background (SGWB) using terrestrial detectors typically involve cross-correlating data from pairs of detectors. The sensitivity of such cross-correlation analyses depends, among other things, on the separation between the two detectors: the smaller the separation, the better the sensitivity. Hence, a colocated detector pair is more sensitive to a gravitational-wave background than a noncolocated detector pair. However, colocated detectors are also expected to suffer from correlated noise from instrumental and environmental effects that could contaminate the measurement of the background. Hence, methods to identify and mitigate the effects of correlated noise are necessary to achieve the potential increase in sensitivity of colocated detectors. Here we report on the first SGWB analysis using the two LIGO Hanford detectors and address the complications arising from correlated environmental noise. We apply correlated noise identification and mitigation techniques to data taken by the two LIGO Hanford detectors, H1 and H2, during LIGO’s fifth science run. At low frequencies, 40–460 Hz, we are unable to sufficiently mitigate the correlated noise to a level where we may confidently measure or bound the stochastic gravitational-wave signal. However, at high frequencies, 460–1000 Hz, these techniques are sufficient to set a 95% confidence level upper limit on the gravitational-wave energy density of Ω(f) < 7.7 × 10[superscript -4](f/900  Hz)[superscript 3], which improves on the previous upper limit by a factor of ~180. In doing so, we demonstrate techniques that will be useful for future searches using advanced detectors, where correlated noise (e.g., from global magnetic fields) may affect even widely separated detectors.National Science Foundation (U.S.)United States. National Aeronautics and Space AdministrationCarnegie TrustDavid & Lucile Packard FoundationAlfred P. Sloan Foundatio