515 research outputs found

    The end-to-end testbed of the Optical Metrology System on-board LISA Pathfinder

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    LISA Pathfinder is a technology demonstration mission for the Laser Interferometer Space Antenna (LISA). The main experiment on-board LISA Pathfinder is the so-called LISA Technology Package (LTP) which has the aim to measure the differential acceleration between two free-falling test masses with an accuracy of 3x10^(-14) ms^(-2)/sqrt[Hz] between 1 mHz and 30 mHz. This measurement is performed interferometrically by the Optical Metrology System (OMS) on-board LISA Pathfinder. In this paper we present the development of an experimental end-to-end testbed of the entire OMS. It includes the interferometer and its sub-units, the interferometer back-end which is a phasemeter and the processing of the phasemeter output data. Furthermore, 3-axes piezo actuated mirrors are used instead of the free-falling test masses for the characterisation of the dynamic behaviour of the system and some parts of the Drag-free and Attitude Control System (DFACS) which controls the test masses and the satellite. The end-to-end testbed includes all parts of the LTP that can reasonably be tested on earth without free-falling test masses. At its present status it consists mainly of breadboard components. Some of those have already been replaced by Engineering Models of the LTP experiment. In the next steps, further Engineering Models and Flight Models will also be inserted in this testbed and tested against well characterised breadboard components. The presented testbed is an important reference for the unit tests and can also be used for validation of the on-board experiment during the mission

    AMS measurements of cosmogenic and supernova-ejected radionuclides in deep-sea sediment cores

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    Samples of two deep-sea sediment cores from the Indian Ocean are analyzed with accelerator mass spectrometry (AMS) to search for traces of recent supernova activity around 2 Myr ago. Here, long-lived radionuclides, which are synthesized in massive stars and ejected in supernova explosions, namely 26Al, 53Mn and 60Fe, are extracted from the sediment samples. The cosmogenic isotope 10Be, which is mainly produced in the Earths atmosphere, is analyzed for dating purposes of the marine sediment cores. The first AMS measurement results for 10Be and 26Al are presented, which represent for the first time a detailed study in the time period of 1.7-3.1 Myr with high time resolution. Our first results do not support a significant extraterrestrial signal of 26Al above terrestrial background. However, there is evidence that, like 10Be, 26Al might be a valuable isotope for dating of deep-sea sediment cores for the past few million years.Comment: 5 pages, 2 figures, Proceedings of the Heavy Ion Accelerator Symposium on Fundamental and Applied Science, 2013, will be published by the EPJ Web of conference

    Assessment of the radiological impact of a decommissioning nuclear power plant in Italy

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    The assessment of the radiological impact of a decommissioning Nuclear Power Plant is presented here through the results of an environmental monitoring survey carried out in the area surrounding the Garigliano Power Plant. The levels of radioactivity in soil, water, air and other environmental matrices are shown, in which {\alpha}, {\beta} and {\gamma} activity and {\gamma} equivalent dose rate are measured. Radioactivity levels of the samples from the Garigliano area are analyzed and then compared to those from a control zone situated more than 100 km away. Moreover, a comparison is made with a previous survey held in 2001. The analyses and comparisons show no significant alteration in the radiological characteristics of the area surroundings the plant, with an overall radioactivity depending mainly from the global fallout and natural sources.Comment: 13 pages, 6 figures, 2 table

    Assessment of the radiological impact of a decommissioning nuclear power plant in Italy

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    The assessment of the radiological impact of a decommissioning Nuclear Power Plant is presented here through the results of an environmental monitoring survey carried out in the area surrounding the Garigliano Power Plant. The levels of radioactivity in soil, water, air and other environmental matrices are shown, in which {\alpha}, {\beta} and {\gamma} activity and {\gamma} equivalent dose rate are measured. Radioactivity levels of the samples from the Garigliano area are analyzed and then compared to those from a control zone situated more than 100 km away. Moreover, a comparison is made with a previous survey held in 2001. The analyses and comparisons show no significant alteration in the radiological characteristics of the area surroundings the plant, with an overall radioactivity depending mainly from the global fallout and natural sources

    Multiple dimensions of excessive daytime sleepiness

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    Background: In this study we investigated subjective measures of sleepiness and related our findings to dimensions of affect, fatigue, emotion, mood and quality of life based on a hypothetical multidimensional model of sleepiness. Methods: Patients referred to a sleep clinic were assessed regarding their excessive daytime sleepiness (EDS), sleep complaints, routine and symptoms. Age, gender and body mass index (BMI), the Epworth Sleepiness Scale (ESS), the Stanford Sleepiness Scale (SSS), the Samn-Perelli fatigue Scale (SPS), the Global Vigor and Affect Scale (GVS and GAS, respectively), the Hospital Anxiety and Depression Scale (HADS-A and HADS-D, respectively), and the Positive and Negative Affect Schedule (PAS and NAS, respectively) scores were recorded. Results: Fifty patients [25 male, 45.2 (18.7) years] completed the questionnaires. The ESS scores were positively correlated with SSS, SPS, HADS-A, HADS-D and NAS scores and negatively with GVS and GAS scores (P<0.05). The SPS (P<0.001) and HADS-A scores (P=0.002) were independently associated with the ESS scores (R2=0.532, adjusted R2 =0.4794, P<0.001). Conclusions: A model of sleepiness that assesses dimensions of fatigue and anxiety could explain the symptom of subjective sleepiness better than the isolated use of the ESS

    Symmetric achromatic low-beta collider interaction region design concept

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    We present a new symmetry-based concept for an achromatic low-beta collider interaction region design. A specially-designed symmetric Chromaticity Compensation Block (CCB) induces an angle spread in the passing beam such that it cancels the chromatic kick of the final focusing quadrupoles. Two such CCBs placed symmetrically around an interaction point allow simultaneous compensation of the 1st-order chromaticities and chromatic beam smear at the IP without inducing significant 2nd-order aberrations to the particle trajectory. We first develop an analytic description of this approach and explicitly formulate 2nd-order aberration compensation conditions at the interaction point. The concept is next applied to develop an interaction region design for the ion collider ring of an electron-ion collider. We numerically evaluate performance of the design in terms of momentum acceptance and dynamic aperture. The advantages of the new concept are illustrated by comparing it to the conventional distributed-sextupole chromaticity compensation scheme.Comment: 12 pages, 17 figures, to be submitted to Phys. Rev. ST Accel. Beam

    Relationship between 129I and 127I contents in bovine thyroid glands from Argentina

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    129I/127I ratios and iodine concentrations in bovine thyroids stemming from Argentina were determined by accelerator mass spectrometry (AMS) and gas chromatography (GC), respectively. From these measurements, a relationship of the 129I/127I ratio with iodine content in the gland was obtained. A weak correlation between the two isotopes was found, suggesting that 129I re-emission from the ocean is not the only process for the 129I deposition in Argentina. Moreover, contributions to the total 129I inventory in the Southern hemisphere from both natural and anthropogenic sources were theoretically studied. Surface compartments present similar contribution from natural sources and nuclear explosions fallout.Fil: Negri, Agustin Eduardo. Comisi√≥n Nacional de Energ√≠a At√≥mica. Gerencia del √Ārea de Investigaci√≥n y Aplicaciones No Nucleares. Gerencia F√≠sica (Centro At√≥mico Constituyentes). Proyecto Tandar; Argentina. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas; ArgentinaFil: Fernandez Niello, Jorge Oscar. Comisi√≥n Nacional de Energ√≠a At√≥mica. Gerencia del √Ārea de Investigaci√≥n y Aplicaciones No Nucleares. Gerencia F√≠sica (Centro At√≥mico Constituyentes). Proyecto Tandar; Argentina. Universidad Nacional de San Mart√≠n; Argentina. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas; ArgentinaFil: Wallner, A.. Universidad de Viena; AustriaFil: Arazi, Andres. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas; Argentina. Comisi√≥n Nacional de Energ√≠a At√≥mica. Gerencia del √Ārea de Investigaci√≥n y Aplicaciones No Nucleares. Gerencia F√≠sica (Centro At√≥mico Constituyentes). Proyecto Tandar; ArgentinaFil: Steier, P.. Universidad de Viena; Austri

    Ultrasensitive search for long-lived superheavy nuclides in the mass range A=288 to A=300 in natural Pt, Pb, and Bi

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    Theoretical models of superheavy elements (SHEs) predict a region of increased stability around the proton and neutron shell closures of Z = 114 and N = 184. Therefore a sensitive search for nuclides in the mass range from A = 288 to A = 300 was performed in natural platinum, lead, and bismuth, covering long-lived isotopes of Eka-Pt (Ds, Z = 110), Eka-Pb (Z = 114), and Eka-Bi (Z = 115). Measurements with accelerator mass spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA) established upper limits for these SHE isotopes in Pt, Pb, and Bi with abundances of <2√ó10-15, <5√ó10-14, and <5√ó10-13, respectively. These results complement earlier searches for SHEs with AMS at VERA in natural thorium and gold, which now amounts to a total number of 37 SHE nuclides having been explored with AMS. In none of our measurements was evidence found for the existence of SHEs in nature at the reported sensitivity level. Even though a few events were observed in the window for Ek293a-Bi, a particularly strong pileup background did not allow a definite SHE isotope identification. The present result sets limits on nuclides around the center of the island of stability, essentially ruling out the existence of SHE nuclides with half-lives longer than ‚ąľ150 million years
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