228 research outputs found

    Sub-LET Threshold SEE cross section dependency with ion energy

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    This study focuses on the ion species and energy dependence of the heavy ion SEE cross section in the sub-LET threshold region through a set of experimental data. In addition, a Monte Carlo based model is introduced and applied, showing a good agreement with the data in the several hundred MeV/n range while evidencing large discrepancies with the measurements in the 10-30 MeV/n interval, notably for the Ne ion. Such discrepancies are carefully analyzed and discussed

    Body size data collected non-invasively from drone images indicate a morphologically distinct Chilean blue whale (Blaenoptera musculus) taxon

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    © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Leslie, M. S., Perkins-Taylor, C. M., Durban, J. W., Moore, M. J., Miller, C. A., Chanarat, P., Bahamonde, P., Chiang, G., & Apprill, A. Body size data collected non-invasively from drone images indicate a morphologically distinct Chilean blue whale (Blaenoptera musculus) taxon. Endangered Species Research, 43, (2020): 291-304, https://doi.org/10.3354/esr01066.The blue whale Balaenoptera musculus (Linnaeus, 1758) was the target of intense commercial whaling in the 20th century, and current populations remain drastically below pre-whaling abundances. Reducing uncertainty in subspecific taxonomy would enable targeted conservation strategies for the recovery of unique intraspecific diversity. Currently, there are 2 named blue whale subspecies in the temperate to polar Southern Hemisphere: the Antarctic blue whale B. m. intermedia and the pygmy blue whale B. m. brevicauda. These subspecies have distinct morphologies, genetics, and acoustics. In 2019, the Society for Marine Mammalogy’s Committee on Taxonomy agreed that evidence supports a third (and presently unnamed) subspecies of Southern Hemisphere blue whale subspecies, the Chilean blue whale. Whaling data indicate that the Chilean blue whale is intermediate in body length between pygmy and Antarctic blue whales. We collected body size data from blue whales in the Gulfo Corcovado, Chile, during the austral summers of 2015 and 2017 using aerial photogrammetry from a remotely controlled drone to test the hypothesis that the Chilean blue whale is morphologically distinct from other Southern Hemisphere blue whale subspecies. We found the Chilean whale to be morphologically intermediate in both overall body length and relative tail length, thereby joining other diverse data in supporting the Chilean blue whale as a unique subspecific taxon. Additional photogrammetry studies of Antarctic, pygmy, and Chilean blue whales will help examine unique morphological variation within this species of conservation concern. To our knowledge, this is the first non-invasive small drone study to test a hypothesis for systematic biology.We are thankful to Foundation MERI (Melimoyu Ecosystem Research Institute) for logistical and funding support. Cruise support in 2017 was provided by the Dalio Foundation (now ‘OceanX’)

    Quantum gravity phenomenology at the dawn of the multi-messenger era—A review

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    The exploration of the universe has recently entered a new era thanks to the multi-messenger paradigm, characterized by a continuous increase in the quantity and quality of experimental data that is obtained by the detection of the various cosmic messengers (photons, neutrinos, cosmic rays and gravitational waves) from numerous origins. They give us information about their sources in the universe and the properties of the intergalactic medium. Moreover, multi-messenger astronomy opens up the possibility to search for phenomenological signatures of quantum gravity. On the one hand, the most energetic events allow us to test our physical theories at energy regimes which are not directly accessible in accelerators; on the other hand, tiny effects in the propagation of very high energy particles could be amplified by cosmological distances. After decades of merely theoretical investigations, the possibility of obtaining phenomenological indications of Planck-scale effects is a revolutionary step in the quest for a quantum theory of gravity, but it requires cooperation between different communities of physicists (both theoretical and experimental). This review, prepared within the COST Action CA18108 “Quantum gravity phenomenology in the multi-messenger approach”, is aimed at promoting this cooperation by giving a state-of-the art account of the interdisciplinary expertise that is needed in the effective search of quantum gravity footprints in the production, propagation and detection of cosmic messengers

    Single view silhouette fitting techniques for estimating tennis racket position

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    Stereo camera systems have been used to track markers attached to a racket, allowing its position to be obtained in three-dimensional (3D) space. Typically, markers are manually selected on the image plane, but this can be time-consuming. A markerless system based on one stationary camera estimating 3D racket position data is desirable for research and play. The markerless method presented in this paper relies on a set of racket silhouette views in a common reference frame captured with a calibrated camera and a silhouette of a racket captured with a camera whose relative pose is outside the common reference frame. The aim of this paper is to provide validation of these single view fitting techniques to estimate the pose of a tennis racket. This includes the development of a calibration method to provide the relative pose of a stationary camera with respect to a racket. Mean static racket position was reconstructed to within ±2 mm. Computer generated camera poses and silhouette views of a full size racket model were used to demonstrate the potential of the method to estimate 3D racket position during a simplified serve scenario. From a camera distance of 14 m, 3D racket position was estimated providing a spatial accuracy of 1.9 ± 0.14 mm, similar to recent 3D video marker tracking studies of tennis

    Validation of energy deposition simulations for proton and heavy ion losses in the CERN Large Hadron Collider

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    Monte Carlo shower simulations are essential for understanding and predicting the consequences of beam losses in high-energy proton and ion colliders. Shower simulations are routinely used at CERN for estimating the beam-induced energy deposition, radiation damage, and radioactivity in the Large Hadron Collider (LHC). Comparing these shower simulations against beam loss measurements is an important prerequisite for assessing the predictive ability of model calculations. This paper validates fluka simulation predictions of beam loss monitor (BLM) signals against BLM measurements from proton fills at 3.5 and 4 TeV and 208^{208}Pb82+^{82+} ion fills at 1.38A  TeV. The paper addresses typical loss scenarios and loss mechanisms encountered in LHC operation, including proton collisions with dust particles liberated into the beams, halo impact on collimators in the betatron cleaning insertion, proton-proton collisions in the interaction points, and dispersive losses due to bound-free pair production in heavy ion collisions. Model predictions and measured signals generally match within a few tens of percent, although systematic differences were found to be as high as a factor of 3 for some regions and source terms
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