Advanced technologies for future ground-based, laser-interferometric gravitational wave detectors

We present a review of modern optical techniques being used and developed for the field of gravitational wave detection. We describe the current state-of-the-art of gravitational waves detector technologies with regard to optical layouts, suspensions and test masses. We discuss the dominant sources and noise in each of these subsystems and the developments that will help mitigate them for future generations of detectors. We very briefly summarise some of the novel astrophysics that will be possible with these upgraded detectors

Atom-optics hologram in the time domain

The temporal evolution of an atomic wave packet interacting with object and reference electromagnetic waves is investigated beyond the weak perturbation of the initial state. It is shown that the diffraction of an ultracold atomic beam by the inhomogeneous laser field can be interpreted as if the beam passes through a three-dimensional hologram, whose thickness is proportional to the interaction time. It is found that the diffraction efficiency of such a hologram may reach 100% and is determined by the duration of laser pulses. On this basis a method for reconstruction of the object image with matter waves is offered.Comment: RevTeX, 13 pages, 8 figures; minor grammatical change

Simulations of the Static Friction Due to Adsorbed Molecules

The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and the number of adsorbed molecules are not controlled in most experiments and are shown to have little effect on the friction. Temperature, molecular geometry and interaction potentials can have larger effects on friction. The observed trends in friction can be understood in terms of a simple hard sphere model.Comment: 13 pages, 13 figure

Coordination and Sustainability of River Observing Activities in the Arctic

To understand and respond to changes in the world’s northern regions, we need a coordinated system of long-term Arctic observations. River networks naturally integrate across landscapes and link the terrestrial and ocean domains. Changes in river discharge reflect changes in the terrestrial water balance, whereas changes in water chemistry are linked to changes in biogeochemical processes and water flow paths. Sustained measurements of river water discharge and water chemistry are therefore essential components of an Arctic observing network. As we strive to establish and sustain long-term observations in the Arctic, these two measurements must be coupled. Although river discharge and chemistry measurements are already coupled to some extent within national boundaries, this is not done in a consistent and coordinated fashion across the pan-Arctic domain. As a consequence, data quality and availability vary widely among regions. International coordination of river discharge and chemistry measurements in the Arctic would be greatly facilitated by formal commitments to maintain a set of core sites and associated measurements that are mutually agreed upon among pan-Arctic nations. Involvement of the agencies currently operating river discharge gauges around the Arctic and establishment of an overarching coordination entity to implement shared protocols, track data quality, and manage data streams would be essential in this endeavor. Focused studies addressing scale-dependent relationships between watershed characteristics and water chemistry, in-stream processes, and estuarine and coastal dynamics are also needed to support interpretation and application of Arctic river observing data as they relate to land and ocean change.Pour comprendre les changements qui s’opèrent dans les régions nordiques du monde et y réagir, nous devons nous doter d’un système coordonné d’observation à long terme dans l’Arctique. Les réseaux fluviaux s’intègrent naturellement dans les paysages et relient le domaine terrestre au domaine océanique. Les changements qui s’exercent dans les réseaux fluviaux sont le reflet des changements dans l’équilibre hydrique terrestre, tandis que les changements qui s’exercent sur l’hydrochimie sont liés aux changements caractérisant les processus biogéochimiques et les parcours d’écoulement de l’eau. Par conséquent, un réseau d’observation arctique devrait essentiellement être assorti de mesures durables d’évacuation des eaux fluviales et d’hydrochimie. Au moment où nous nous efforçons d’établir et de soutenir des observations à long terme dans l’Arctique, ces deux types de mesures doivent être suivies en parallèle. Bien que les mesures de l’évacuation fluviale et les mesures chimiques soient déjà, dans une certaine mesure, suivies en parallèle à l’intérieur des frontières nationales, cela ne se fait pas de manière uniforme et coordonnée à la grandeur du domaine panarctique, et en conséquence, la qualité et la disponi­bilité des données varient beaucoup d’une région à l’autre. La coordination internationale des mesures d’évacuation fluviale et chimiques dans l’Arctique serait grandement facilitée par l’existence d’engagements officiels visant à maintenir une série d’emplacements fondamentaux et de mesures connexes fixées par entente mutuelle au sein des nations panarctiques. La partic­ipation des agences qui gèrent les manomètres d’évacuation fluviale dans l’Arctique et l’établissement d’une entité de coordi­nation générale mettant en oeuvre des protocoles partagés, vérifiant la qualité des données et gérant les flux de données seraient également essentiels. Des études ciblées portant sur les relations influencées par l’échelle entre les caractéristiques du bassin hydrographique et l’hydrochimie, sur les processus s’opérant à l’intérieur des cours d’eau et sur la dynamique des estuaires et des rives s’avèrent également nécessaires pour étayer l’interprétation et l’application des données d’observation fluviale de l’Arctique en matière de changement terrestre et océanique

Lasers and optics: Looking towards third generation gravitational wave detectors

Third generation terrestrial interferometric gravitational wave detectors will likely require significant advances in laser and optical technologies to reduce two of the main limiting noise sources: thermal noise due to mirror coatings and quantum noise arising from a combination of shot noise and radiation pressure noise. Increases in laser power and possible changes of the operational wavelength require new high power laser sources and new electro-optic modulators and Faraday isolators. Squeezed light can be used to further reduce the quantum noise while nano-structured optical components can be used to reduce or eliminate mirror coating thermal noise as well as to implement all-reflective interferometer configurations to avoid thermal effects in mirror substrates. This paper is intended to give an overview on the current state-of-the-art and future trends in these areas of ongoing research and development.NSF/PHY0555453NSF/PHY0757968NSF/PHY0653582DFG/SFB/407DFG/SFB/TR7DFG/EXC/QUES

Teaching of Energy Issues: A debate proposal for a GLobal Reorientation

The growing awareness of serious difficulties in the learning of energy issues has produced a great deal of research, most of which is focused on specific conceptual aspects. In our opinion, the difficulties pointed out in the literature are interrelated and connected to other aspects (conceptual as well as procedural and axiological), which are not sufficiently taken into account in previous research. This paper aims to carry out a global analysis in order to avoid the more limited approaches that deal only with individual aspects. From this global analysis we have outlined 24 propositions that are put forward for debate to lay the foundations for a profound reorientation of the teaching of energy topics in upper high school courses, in order to facilitate a better scientific understanding of these topics, avoid many students' misconceptions and enhance awareness of the current situation of planetary emergency

Search for high-energy neutrinos from gravitational wave event GW151226 and candidate LVT151012 with ANTARES and IceCube

The Advanced LIGO observatories detected gravitational waves from two binary black hole mergers during their first observation run (O1). We present a high-energy neutrino follow-up search for the second gravitational wave event, GW151226, as well as for gravitational wave candidate LVT151012. We find two and four neutrino candidates detected by IceCube, and one and zero detected by Antares, within ±500 s around the respective gravitational wave signals, consistent with the expected background rate. None of these neutrino candidates are found to be directionally coincident with GW151226 or LVT151012. We use nondetection to constrain isotropic-equivalent high-energy neutrino emission from GW151226, adopting the GW event's 3D localization, to less than 2×1051-2×1054 erg. © 2017 American Physical Society