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Mathis F.,University of Liege | Bodu P.,French National Center for Scientific Research | Dubreuil O.,Center Spatial Of Liege | Salomon H.,University of Liege
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2014

Les Bossats, near Ormesson, France, is a newly discovered late Mousterian open air site dated to around 47,000 years ago by thermoluminescence. The archaeological level, fossilized by loess, revealed a rich industry based on the discoid mode, associated with numerous fragments of red and yellow iron oxide-rich rocks showing clear traces of powder production (abrasion, striation, scraping), which are exceptional remains for this remote period. Archeological material and geological samples from the close environment were studied by PIXE and by petrographical observations made on thin sections. The geological sources were identified by means of PIXE analyses on two IBA facilities: AGLAE (2 MV tandem) at the C2RMF in Paris and the cyclotron of the IPNAS (University of Liège). We paid particular attention to the comparison of results obtained on both installations by using the same set of geological standards and by a fine evaluation of the limit of detection relative to each trace elements of interest for both experimental set ups. The elemental fingerprint of one geological source of iron-rich concretions corresponds clearly with the archaeological collection. At least, this investigation demonstrates that the colouring materials were minutely selected in the close neighbouring of the site by the Neanderthals. © 2014 Elsevier B.V. All rights reserved.

Schmutz W.,PMOD WRC | Shapiro A.I.,PMOD WRC | Kretzschmar M.,University of Orleans | Zhukov A.N.,Moscow State University | And 2 more authors.
Solar Physics | Year: 2013

The Large Yield Radiometer (LYRA) is an XUV-EUV-MUV (soft X-ray to mid-ultraviolet) solar radiometer onboard the European Space Agency Project for On-Board Autonomy 2 (PROBA2) mission, which was launched in November 2009. LYRA acquires solar-irradiance measurements at a high cadence (nominally 20 Hz) in four broad spectral channels, from soft X-ray to MUV, which have been chosen for their relevance to solar physics, space weather, and aeronomy. We briefly review the design of the instrument, give an overview of the data products distributed through the instrument website, and describe how the data are calibrated. We also briefly present a summary of the main fields of research currently under investigation by the LYRA consortium. © 2013 Springer Science+Business Media Dordrecht.

Simar J.F.,Center Spatial Of Liege | Stockman Y.,Center Spatial Of Liege | Surdej J.,University of Liege
Applied Optics | Year: 2015

Space observations of fainter and more distant astronomical objects constantly require telescope primary mirrors with larger sizes. The diameters of monolithic primary mirrors are restricted to 10 m because of manufacturing limitations. For space telescopes, the primary mirrors are limited to less than 5 m due to fairing capacity. Segmented primary mirrors thus constitute an alternative solution to deal with the steady increase of primary mirror size. The optical path difference between the individual segments must be close to 0 (a few nanometers) in order to be diffraction-limited. In this paper, we propose a new intersegment piston sensor based on the coherence measurement of a star image. This sensor is intended to be used in the co-phasing system of future segmented mirrors. © 2015 Optical Society of America.

Mazy E.,Center Spatial Of Liege | Hellin M.L.,Center Spatial Of Liege
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

In the framework of instrument calibration, straylight issues are a critical aspect that can deteriorate the optical performances of instrument. To cope with this, a new facility is designed dedicated for in-field and far field straylight characterization: up to 10-8 for in-field and up to 10-10 for far field straylight in the visible to NIR spectral ranges. Moreover, from previous straylight test performed at CSL, vacuum conditions are needed for reaching the 10-10 rejection requirement mainly to avoid air/dust diffusion. The major constrains are to design a straylight facility either for in-field and out-field straylight measurements. That requires high dynamic range at source level and a high radiance point source allowing small diverging collimated beam. Moreover, the straylight facility has to be implemented into a limited envelope and has to be built with vacuum compatible materials and black coating. As checking the facility performance requires an instrument better than the facility itself, that is no easy to find, so that the performances have been estimated through a modelisation into a non sequential optical software. This modelisation is based on CAD importation of mechanical design, on BRDF characteristics of black coating and on statistical averaging of ray tracing at instrument entrance. © 2012 SPIE.

Roose S.,Center Spatial Of Liege | Stockman Y.,Center Spatial Of Liege | Sodnik Z.,European Space Agency
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The Coarse Lateral Sensor (CLS) is a system able to measure the lateral position between two satellites. It bridges the gap between the coarse alignment accuracy achievable with radio frequency metrology or global positioning systems (GPS), and the alignment accuracy required to start higher-precision optical metrology systems based on interferometry. The system is a standalone unit. Once connected to an unregulated 28V power-supply, it delivers, the lateral position of a corner cube retro-reflector and tracks this position at a rate of 10 Hz. The system is operational with the sun in its field-of-view. The coarse lateral sensor has successfully undergone thermal qualification (40 C and -30 °C), and vibration test (highlevel sinus, random and shock test in the 3-axis). © 2013 SPIE.

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