Influence of the 6^1S_0-6^3P_1 Resonance on Continuous Lyman-alpha Generation in Mercury

Continuous coherent radiation in the vacuum-ultraviolet at 122 nm (Lyman-alpha) can be generated using sum-frequency mixing of three fundamental laser beams in mercury vapour. One of the fundamental beams is at 254 nm wavelength, which is close to the 6^1S_0-6^3P_1 resonance in mercury. Experiments have been performed to investigate the effect of this one-photon resonance on phasematching, absorption and the nonlinear yield. The efficiency of continuous Lyman-alpha generation has been improved by a factor of 4.5.Comment: 8 pages, 7 figure

Antihydrogen formation dynamics in a multipolar neutral anti-atom trap

Antihydrogen production in a neutral atom trap formed by an octupole-based magnetic field minimum is demonstrated using field-ionization of weakly bound anti-atoms. Using our unique annihilation imaging detector, we correlate antihydrogen detection by imaging and by field-ionization for the first time. We further establish how field-ionization causes radial redistribution of the antiprotons during antihydrogen formation and use this effect for the first simultaneous measurements of strongly and weakly bound antihydrogen atoms. Distinguishing between these provides critical information needed in the process of optimizing for trappable antihydrogen. These observations are of crucial importance to the ultimate goal of performing CPT tests involving antihydrogen, which likely depends upon trapping the anti-atom

Search For Trapped Antihydrogen

We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9 positrons to produce 6 10^5 antihydrogen atoms, we have identified six antiproton annihilation events that are consistent with the release of trapped antihydrogen. The cosmic ray background, estimated to contribute 0.14 counts, is incompatible with this observation at a significance of 5.6 sigma. Extensive simulations predict that an alternative source of annihilations, the escape of mirror-trapped antiprotons, is highly unlikely, though this possibility has not yet been ruled out experimentally.Comment: 12 pages, 7 figure

Closing in on the properties of antihydrogen

Conference review, with some speculation in the closing section

Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps

A newly constructed apparatus at the National Institute of Standards and Technology (NIST) is designed for the isolation, manipulation, and study of highly charged ions. Highly charged ions are produced in the NIST electron-beam ion trap (EBIT), extracted through a beamline that selects a single mass/charge species, then captured in a compact Penning trap. The magnetic field of the trap is generated by cylindrical NdFeB permanent magnets integrated into its electrodes. In a room-temperature prototype trap with a single NdFeB magnet, species including Ne10+ and N7+ were confined with storage times of order 1 second, showing the potential of this setup for manipulation and spectroscopy of highly charged ions in a controlled environment. Ion capture has since been demonstrated with similar storage times in a more-elaborate Penning trap that integrates two coaxial NdFeB magnets for improved B-field homogeneity. Ongoing experiments utilize a second-generation apparatus that incorporates this two-magnet Penning trap along with a fast time-of-flight MCP detector capable of resolving the charge-state evolution of trapped ions. Holes in the two-magnet Penning trap ring electrode allow for optical and atomic beam access. Possible applications include spectroscopic studies of one-electron ions in Rydberg states, as well as highly charged ions of interest in atomic physics, metrology, astrophysics, and plasma diagnostics.Comment: Proceedings of CDAMOP-2011, 13-16 Dec 2011, Delhi, India. To be published by Springer Verla

The effect on melanoma risk of genes previously associated with telomere length.

Telomere length has been associated with risk of many cancers, but results are inconsistent. Seven single nucleotide polymorphisms (SNPs) previously associated with mean leukocyte telomere length were either genotyped or well-imputed in 11108 case patients and 13933 control patients from Europe, Israel, the United States and Australia, four of the seven SNPs reached a P value under .05 (two-sided). A genetic score that predicts telomere length, derived from these seven SNPs, is strongly associated (P = 8.92x10(-9), two-sided) with melanoma risk. This demonstrates that the previously observed association between longer telomere length and increased melanoma risk is not attributable to confounding via shared environmental effects (such as ultraviolet exposure) or reverse causality. We provide the first proof that multiple germline genetic determinants of telomere length influence cancer risk.This is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/jnci/dju26

A smart combination of a solar assisted absorption chiller and a power productive gas expansion unit for cogeneration of power and cooling

Solar assisted absorption chiller is one of efficient cooling production systems for large cooling capacities. The main drawback of this system is that in addition to the electricity consumption, it demands for a lot of heat in relatively high temperature range of 90–120 °C, though the solar system may provide a significant portion of this heating demand. On the other hand, in gas transmission systems, there are some expansion stations in which gas pressure is reduced considerably and this pressure drop causes temperature collapse in gas stream. Power productive gas expansion station (PPGES) is the most recent design proponed for these stations in which the unit is equipped with power generation systems. In this work, taking advantage of this temperature fall for cooling production is proposed by coupling the station with an absorption chiller. In this case, the chiller could also provide the heating demand of the expansion station. In order to evaluate the effectiveness of the proposed configuration, it is simulated for a case study in Denmark, i.e. Aarhus University (AU) hospital absorption chiller and Viborg gas station. The results show that the expansion station could provide an annual cooling production contribution of 27%. In addition, the paper presents an extensive economic assessment to prove the impact of the proposed system economically. The results show a great enhancement in the levelized cost of energy (LCOE) of the case study in case of employing the hybrid system instead of the conventional chiller

Fundamental Properties of and Transition to a Fully Renewable Pan-European Power System

We introduce a top-down stylized model to analyse the impact of a transition to a European power system based only on wind and solar power. Wind and solar power generation is calculated from high-resolution weather data and based on the country specific electricity demand alone, we introduce a model of the conventional power system that facilitates simple spatio-temporal modelling of its macroscopic behavior without direct reference to the underlying technological, economical, and political development in the system. Using this model, we find that wind and solar power generation can replace conventional power generation and power capacity to a large degree if power transmission across the continent is made possible

Further evidence for low-energy protonium production in vacuum

We describe an experiment performed in the ATHENA apparatus in which there is evidence that the antiproton-proton bound state, protonium, has been produced at very low energies in vacuum following the interaction of cold antiprotons with a trapped cloud of molecular hydrogen ions. The latter were confined in a centrifugally separated belt outside a positron plasma used for antihydrogen formation. Studies have been performed at low positron plasma temperatures in which the protonium annihilation signal has been identified along with that from antihydrogen, and we discuss how their contributions can be disentangled. With the positron plasma heated to around 10000K the ions become distributed in the positrons, and the majority of the annihilation signal can be explained in terms of protonium formation, as antihydrogen creation is heavily suppressed. In this case we compare the observed protonium formation ratewith expectations from theory and find reasonable accord, when experimental systematics are taken into account. The effect on the annihilation signals of the passage of an electron current through a pre-loaded positron plasma has been studied in detail, and the results are presented here for the first time