Time calibration of the ANTARES neutrino telescope

The ANTARES deep-sea neutrino telescope comprises a three-dimensional array of photomultipliers to detect the Cherenkov light induced by upgoing relativistic charged particles originating from neutrino interactions in the vicinity of the detector. The large scattering length of light in the deep sea facilitates an angular resolution of a few tenths of a degree for neutrino energies exceeding 10 TeV. In order to achieve this optimal performance, the time calibration procedures should ensure a relative time calibration between the photomultipliers at the level of similar to 1 ns. The methods developed to attain this level of precision are described

The positioning system of the ANTARES Neutrino Telescope

The ANTARES neutrino telescope, located 40km off the coast of Toulon in the Mediterranean Sea at a mooring depth of about 2475m, consists of twelve detection lines equipped typically with 25 storeys. Every storey carries three optical modules that detect Cherenkov light induced by charged secondary particles (typically muons) coming from neutrino interactions. As these lines are flexible structures fixed to the sea bed and held taut by a buoy, sea currents cause the lines to move and the storeys to rotate. The knowledge of the position of the optical modules with a precision better than 10cm is essential for a good reconstruction of particle tracks. In this paper the ANTARES positioning system is described. It consists of an acoustic positioning system, for distance triangulation, and a compass-tiltmeter system, for the measurement of the orientation and inclination of the storeys. Necessary corrections are discussed and the results of the detector alignment procedure are described

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

’n Beroep op landskapkompensasie

Ingold has used Marx’s distinction between exchange value and use value to distinguish between land and landscape. Land, Ingold suggests, is abstracted, quantitative and interchangeable. Landscape, by contrast, is qualitative and emerges as habitation’s embodiment of the history of inhabitants’ activities, projects and livelihoods. We use this distinction to argue that the 1913 Land Act effectively created a white monopoly on the production of landscape. By closely considering some of the resulting landscapes, we argue that a significant consequence of this monopoly has been the emergence of what we call the territorial ontology. We characterize this ontology as a world in which land and landscape are collapsed into territory – a bounded, possessed collection of qualities value can be extracted from. This is the world of colonial modernity’s racialized relations of production. In the second part of our article, we examine the North-West University’s landscape art collection and using Ingold to illuminate the relationship between landscapes and representations of landscapes, we argue that these representations draw attention to the world and as such form a part of the complex holding the territorial ontology in place. After demonstrating that the territorial ontology has been central to the racialization of the relations of production in South Africa’s colonial modernity, we call for landscape restitution and suggest that universities are the spaces from which to lead this initiative.Ingold het Marx se onderskeid tussen ruil-/wisselwaarde en verbruikerswaarde gebruik om tussen land en landskap te onderskei. Ingold suggereer dat land is geabstraheer, kwantitatief en verwisselbaar. Landskap daarenteen is kwalitatief en ontwikkel as bewoning – ‚n konsep wat die geskiedenis van die inwoners, hul aktiwiteite, projekte en leefwyse beliggaam. Ons gebruik hierdie onderskeid om te argumenteer dat die Grondgebiedewet van 1913 suksesvol daarin geslaag het om ‚n wit monopolie te skep ten opsigte van die produksie van landskappe. Deur ‚n noukeurige inagneming van sodanige landskappe argumenteer ons dat ʼn unieke gevolg van hierdie monopolie dui op die begin van wat ons die territoriale ontologie noem. Ons beskryf hierdie ontologie as ‚n wêreld waarin land en landskap verval het in ‚n bepaalde gebiedsbesitting van waaruit kwaliteitswaardes afgelei sou kon word. Dit is die wêreld van koloniale moderniteit se rasgebaseerde verhoudings van produksie. In die tweede deel van ons artikel ondersoek ons die Noord-Wes Universiteit se landskapskunsversameling en gebruik ons Ingold om die verhouding tussen landskappe en representasies van landskappe te belig. Ons argumenteer dat hierdie representasies die aandag vestig op die wêreld en as sodanig deel vom van die komplekse instandhouding van die territoriale ontologie. Nadat ons gedemonstreer het dat die territoriale ontology sentraal tot die rasgedrewe verhoudingsproduksie in Suid-Afrika se koloniale moderniteit, rig ons ‚n versoek vir landskapkompensasie en stel ons voor dat universiteite die ruimtes is van waar hierdie inisiatief gelei moet word.http://reference.sabinet.co.za/sa_epublication/saja

Bicontinuous microemulsions with extremely high temperature stability based on skin friendly oil and sugar surfactant

Schulreich C, Angermann C, Hoehn S, et al. Bicontinuous microemulsions with extremely high temperature stability based on skin friendly oil and sugar surfactant. Colloids And Surfaces A Physicochemical And Engineering Aspects. 2013;418:39-46.In the present article the phase behavior of microemulsions based on isononyl isononanoate (Lanol 99), sugar surfactant Simulsol SL55 (C-12/14 G(1.3)), D2O/water, and the cosurfactant benzyl alcohol is studied and the bicontinuous phase is identified. Using small angle neutron scattering (SANS) the internal structure of the bicontinuous phase is characterized. In the experiments a temperature range from 261 K to 343 K was covered. The prepared microemulsions were found to exhibit nearly no temperature dependence with respect to their structure and phase behavior. At low temperatures inside the microemulsions water exists in a supercooled liquid state. (C) 2012 Published by Elsevier B.V

Time calibration of the ANTARES neutrino telescope

The ANTARES deep-sea neutrino telescope comprises a three-dimensional array of photomultipliers to detect the Cherenkov light induced by upgoing relativistic charged particles originating from neutrino interactions in the vicinity of the detector. The large scattering length of light in the deep sea facilitates an angular resolution of a few tenths of a degree for neutrino energies exceeding 10 TeV. In order to achieve this optimal performance, the time calibration procedures should ensure a relative time calibration between the photomultipliers at the level of similar to 1 ns. The methods developed to attain this level of precision are described

A fast algorithm for muon track reconstruction and its application to the ANTARES neutrino telescope RID F-1098-2010

An algorithm is presented, that provides a fast and robust reconstruction of neutrino induced upward-going muons and a discrimination of these events from downward-going atmospheric muon background in data collected by the ANTARES neutrino telescope. The algorithm consists of a hit merging and hit selection procedure followed by fitting steps for a track hypothesis and a point-like light source. It is particularly well-suited for real time applications such as online monitoring and fast triggering of optical follow-up observations for multi-messenger studies. The performance of the algorithm is evaluated with Monte Carlo simulations and various distributions are compared with that obtained in ANTARES data. (C) 2011 Elsevier B.V. All rights reserved

First search for neutrinos in correlation with gamma-ray bursts with the ANTARES neutrino telescope

<p>A search for neutrino-induced muons in correlation with a selection of 40 gamma-ray bursts that occurred in 2007 has been performed with the ANTARES neutrino telescope. During that period, the detector consisted of 5 detection lines. The ANTARES neutrino telescope is sensitive to TeV-PeV neutrinos that are predicted from gamma-ray bursts. No events were found in correlation with the prompt photon emission of the gamma-ray bursts and upper limits have been placed on the flux and fluence of neutrinos for different models.</p>

Search for a correlation between ANTARES neutrinos and Pierre Auger Observatory UHECRs arrival directions

A multimessenger analysis optimized for a correlation of arrival directions of ultra-high energy cosmic rays (UHECRs) and neutrinos is presented and applied to 2190 neutrino candidate events detected in 2007-2008 by the ANTARES telescope and 69 UHECRs observed by the Pierre Auger Observatory between 2004 January 1 and 2009 December 31. No significant correlation is observed. Assuming an equal neutrino flux (E-2 energy spectrum) from all UHECR directions, a 90% CL upper limit on the neutrino flux of 5.0 x 10(-8) GeV cm(-2) s(-1) per source is derived