Recent developments in frequency metrology and optical clocks have been based on electronic transitions in atoms and singly charged ions as references. The control over all relevant degrees of ...freedom in these atoms has enabled relative frequency uncertainties at a level of 10−18. This accomplishment not only allows for extremely accurate time and frequency measurements, but also to probe our understanding of fundamental physics, such as a possible variation of fundamental constants, a violation of the local Lorentz invariance, and the existence of forces beyond the standard model of physics. In addition, novel clocks are driving the development of sophisticated technical applications. Crucial for applications of clocks in fundamental physics are a high sensitivity to effects beyond the standard model and a small frequency uncertainty of the clock. Highly charged ions offer both. They possess optical transitions which can be extremely narrow and less sensitive to external perturbations compared to current atomic clock species. The large selection of highly charged ions offers narrow transitions that are among the most sensitive ones for the “new physics” effects. Recent experimental advances in trapping and sympathetic cooling of highly charged ions will in the future enable advanced quantum logic techniques for controlling motional and internal degrees of freedom and thus enable high-accuracy optical spectroscopy. Theoretical progress in calculating the properties of selected highly charged ions has allowed the evaluation of systematic shifts and the prediction of the sensitivity to the physics beyond the standard model. New theoretical challenges and opportunities emerge from relativistic, quantum electrodynamics, and nuclear-size contributions that become comparable with interelectronic correlations. This article reviews the current status of the field, addresses specific electronic configurations and systems which show the most promising properties for research, their potential limitations, and the techniques for their study.
The Gamma Factory initiative proposes to develop novel research tools at CERN by producing, accelerating, and storing highly relativistic, partially stripped ion beams in the SPS and LHC storage ...rings. By exciting the electronic degrees of freedom of the stored ions with lasers, high‐energy narrow‐band photon beams will be produced by properly collimating the secondary radiation that is peaked in the direction of ions' propagation. Their intensities, up to 1017 photons per second, will be several orders of magnitude higher than those of the presently operating light sources in the particularly interesting γ–ray energy domain reaching up to 400 MeV. This article reviews opportunities that may be afforded by utilizing the primary beams for spectroscopy of partially stripped ions circulating in the storage ring, as well as the atomic‐physics opportunities made possible by the use of the secondary high‐energy photon beams. The Gamma Factory will enable ground‐breaking experiments in spectroscopy and novel ways of testing fundamental symmetries of nature.
The Gamma Factory is a new concept for producing, storing, and employing highly relativistic, partially stripped ion beams in the CERN accelerator complex. The present paper reviews research opportunities in atomic physics and related fields that open up with the advent of this radically novel experimental tool.
Coulomb crystallization of highly charged ions Schmöger, L.; Versolato, O. O.; Schwarz, M. ...
Science (American Association for the Advancement of Science),
03/2015, Volume:
347, Issue:
6227
Journal Article
Peer reviewed
Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions ...(HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically 40Ar13+) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be+ ions. We also demonstrate cooling of a single Ar13+ ion by a single Be+ ion—the prerequisite for quantum logic spectroscopy with a potential 10–19 accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.
Floods are becoming increasingly influential in coastal cities due to the intensification of extreme weather events. The impacts of flooding go beyond damages to infrastructure, it also affects human ...health. During floods, discharge of sewage into streets increases exposure to pathogens causing gastrointestinal (GI) illnesses. A potential strategy for coastal protection during weather hazards is the use of flood protection ecosystem services, but their effectiveness at ameliorating the impact of floods on GI illnesses remain understudied. Here we explore the relationship between extreme rainfall, flood protection ecosystem services, and the occurrence of Medicare claims for gastrointestinal (GI) illnesses in Puerto Rico. We first conducted model averaging to detect variables explaining flood impact for the years (1999–2014), and then used these variables as predictors in a spatio-temporal analysis of GI illness in the same period (1999–2013). Our results show that flood impact varies proportionally with extreme rainfall, and inversely with flood protection ecosystem services, particularly due to the presence of karst soils. The protective effect of karst soils is lost when there is a high percentage of people living in flood prone areas, as suggested by a significant interaction effect between these two variables. In support of our hypotheses, cases of GI illness also spike after extreme rainfall events and are affected by the interaction effect of karst soils and people living in flood prone areas. Our results support the linkage between extreme weather events, flood damages and GI illnesses, and suggests a buffering role of ecosystem services that promote rainfall infiltration. The relevance of these ecosystem services, however, is affected by planning decisions such as residential development in flood prone areas. Our results help inform planning strategies for future weather hazards, accounting for the role of natural and built infrastructure on minimizing flood impacts and human health effects.
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•Extreme rain events in Puerto Rico correlate with spikes in Gastro Intestinal (GI) illness.•Permeable karst soils help reduce flood impacts and GI illnesses according to FEMA and Medicare claims data.•The benefits of karst soils are lost in areas with a high percentage of people living in flood zones.
Classic multi-criteria group decision making models that have a high amount of alternatives are unmanageable for the experts. This is because they have to provide one value per each alternative and ...criteria. In this paper, we focus on solving this issue by carrying out multi-criteria group decision making methods using a different novel approach. Concretely, fuzzy ontologies reasoning procedures are used in order to automatically obtain the alternatives ranking classification. Thanks to our novel methodology, experts only need to provide the importance of a small set of criteria values making it possible for experts to perform multi-criteria group decision making procedures that have a high amount of alternatives without having to directly deal with them. Furthermore, in order to allow experts to provide their preferences in a comfortable way, multi-granular fuzzy linguistic modelling is used in order to allow each expert to choose the linguistic label set that better fits him/her.
For more than 40 years, most astrophysical observations and laboratory studies of two key soft x-ray diagnostic 2p - 3d transitions, 3C and 3D, in Fe XVII ions found oscillator strength rations ...f(3C)/f(3D) disagreeing with theory, but uncertainties had precluded definitive statements on this much studied conundrum. Here, we resonantly excite these lines using synchrotron radiation at PETRA III, and reach, at a millionfold lower photon intensities, a 10 times higher spectral resolution, and 3 times smaller uncertainty than earlier work. Our final result of f(3C)/f(3D) = 3.09(8)(6) supports many of the earlier clean astrophysical and laboratory observations, while departing by five sigmas from our own newest large-scale ab initio calculations, and excluding all proposed explanations, including those invoking nonlinear effects and population transfers.
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