457 research outputs found

    Methods of Increasing Terminal Airspace Flexibility and Control Authority

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    The focus of the NRA contract is to develop a What-if Analysis Tool for planning Departure Management Programs (DMP) at airports. This final report summarizes the work conducted throughout the base year, with a focus on use case specification for the what-if analysis capability and the implementation of the What-if Analysis Tool and its application to traffic and weather scenarios at Charlotte Douglas International Airport (CLT)

    Investigations on the Luminescence Properties of Quartz and Feldspars Extracted from Loess in the Canterbury Plains, New Zealand South Island

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    The applicability of the single-aliquot regenerative-dose (SAR) protocol, by using the optically stimulated lumi-nescence (OSL) signal of quartz as well as the post-infraredā€“infrared (pIRIR) signals of polymineral fine grains, namely pIRIR225 and pIRIR290, was assessed for dating loess in New Zealand South Island. OSL signals of quartz grains displayed low sensitivity. However, the application of repeated irradiation/bleaching cycles did not result in an increase in sensitivity; annealing in the 300ā€“500Ā°C temperature range generated the sensitisation of both the 110Ā°C thermoluminescence (TL) peak as well as the OSL signal, likely by activation of yet unidentified luminescence centres. After heating, the quartz signal is comparable to that of ideal samples, but the annealing is precluding successful dating. On the other hand, feldspar infrared-stimulated signals displayed satisfactory properties, al-lowing estimation of ages ranging from 14 Ā± 1ā€“29 Ā± 3 ka for the investigated deposit. It was shown that pIRIR225 and pIRIR290 methods have potential for dating loess in the South Island of New Zealand, based on the following observations: (i) Dose recovery tests were successful with recovered-to-given dose ratios with a <10% deviation from unity, (ii) constant residual values of about 4 Gy and about 10 Gy were obtained after exposures for 48 h in the case of pIRIR225 signals and 96 h in the case of pIRIR290 signals, respectively, (iii) while a slight dose-dependence of the residual was reported, and for a dose as large as 1600 Gy the residual values are ā‰…9 Gy and ā‰…19 Gy for pIRIR225 and pIRIR290 signals, respectively

    Integrating Neural Networks with a Quantum Simulator for State Reconstruction

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    We demonstrate quantum many-body state reconstruction from experimental data generated by a programmable quantum simulator, by means of a neural network model incorporating known experimental errors. Specifically, we extract restricted Boltzmann machine (RBM) wavefunctions from data produced by a Rydberg quantum simulator with eight and nine atoms in a single measurement basis, and apply a novel regularization technique to mitigate the effects of measurement errors in the training data. Reconstructions of modest complexity are able to capture one- and two-body observables not accessible to experimentalists, as well as more sophisticated observables such as the R\'enyi mutual information. Our results open the door to integration of machine learning architectures with intermediate-scale quantum hardware.Comment: 15 pages, 13 figure

    First identification of excited states in the Tz_z = 1/2 nucleus 93^{93}Pd

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    The first experimental information about excited states in the N = Z + 1 nucleus 93Pd is presented. The experiment was performed using a 205 MeV 58Ni beam from the Vivitron accelerator at IReS, Strasbourg, impinging on a bismuth-backed 40Ca target. Gamma-rays, neutrons and charged particles emitted in the reactions were detected using the Ge detector array Euroball, the Neutron Wall liquid-scintillator array and the Euclides Si charged-particle detector system. The experimental level scheme is compared with the results of new shell model calculations which predict a coupling scheme with aligned neutron-proton pairs to greatly influence the level structure of Nā‰ˆZN\approx Z nuclei at low excitation energies

    ESTIMATION OF RADIONUCLIDES IN SOILS -A COMPARISON OF METHODS FOR ANNUAL DOSE IN LUMINESCENCE DATING

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    Abstract. A study was made in order to compare and test the performance of several methods for the annual radiation dose determination in luminescence dating. The following techniques were used: instrumental neutron activation, high resolution gamma ray spectrometry and alpha spectrometry. Detailed analysis was carried out through gamma spectrometry, the activities of different nuclides ( Tl) in the uranium and thorium series being measured, as well as 40 K. The potential of this method in checking the occurrence of radioactive disequilibrium in the series was investigated. The assumption that radium disequilibrium caused by the percolation of groundwater in soils can be encountered was supported by our finds. The consistency of the results obtained through the three different methods indicate the reliability of using high resolution gamma ray spectrometry as a fast and accurate method for measuring natural radionuclides concentrations in luminescence dating and as well for purposes of environmental monitoring

    On the importance of grain size in luminescence dating using quartz

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    There are two major problems commonly encountered when applying Optically Stimulated Luminescence (OSL) dating in the high dose range: (i) age discrepancy between different grain sizes, and (ii) age underestimation. A marked and systematic discrepancy between fine-grain (4ā€“11 Ī¼m) and coarse-grain (63ā€“90 Ī¼m) quartz single aliquot regeneration protocol (SAR) ages has been reported previously for Romanian and Serbian loess >40 ka (De of āˆ¼100 Gy), generally with fine-grain ages underestimating the depositional age. In this paper, we show a similar age pattern for two grain size fractions from Chinese loess, thus pointing to a potential worldwide phenomenon. While age underestimation is often attributed to signal saturation problems, this is not the case for fine grain material, which saturates at higher doses than coarse grains, yet begins to underestimate true ages earlier. Here we examine the dose response curves of quartz from different sedimentary contexts around the world, using a range of grain sizes (diameters of 4ā€“11 Ī¼m, 11ā€“30 Ī¼m, 35ā€“50 Ī¼m, 63ā€“90 Ī¼m, 90ā€“125 Ī¼m, 125ā€“180 Ī¼m, and 180ā€“250 Ī¼m). All dose response curves can be adequately described by a sum of two saturating exponential functions, whose saturation characteristics (D0 values) are clearly anticorrelated with grain diameter (Ļ†) through an inverse square root relationship, D0 = A/āˆšĻ†, where A is a scaling factor. While the mechanism behind this grain-size dependency of saturation characteristics still needs to be understood, our results show that the observation of an extended SAR laboratory dose response curve does not necessarily enable high doses to be recorded accurately, or provide a corresponding extended age range
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