10 research outputs found
An Approach to Identifying Bird Songs: A Key to more than 300 Songs in the Pipeline Road Area, Soberanía National Park, Panama
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CesrTA Retarding Field Analyzer Modeling Results
Retarding field analyzers (RFAs) provide an effective measure of the local electron cloud density and energy distribution. Proper interpretation of RFA data can yield information about the behavior of the cloud, as well as the surface properties of the instrumented vacuum chamber. However, due to the complex interaction of the cloud with the RFA itself, understanding these measurements can be nontrivial. This paper examines different methods for interpreting RFA data via cloud simulation programs. Techniques include postprocessing the output of a simulation code to predict the RFA response; and incorporating an RFA model into the cloud modeling program itself
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Progress in studies of Electron-Cloud-Induced Optics Distortions at CESRTA
The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent betatron tune shifts for a variety of electron and positron beam energies, bunch population levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced lowenergy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation program packages has allowed determination of the sensitivity of these measurements to physical parameters characterizing the synchrotron radiation flux, the production of photoelectrons on the vacuum chamberwall, the beam emittance, lattice optics,and the secondary-electron yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modeling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders
Measurements of electron cloud growth and mitigation in dipole, quadrupole, and wiggler magnets
The first fossil owls (Aves: Strigiformes) from the Paleogene of Asia and a review of the fossil record of Strigiformes
e fossil record of owls (Strigiformes) is one of the most extensive among the neornithine birds, yet at the same time largely restricted geographically to Europe and North America. Various fossil owls are known from the Paleocene (ca. 60 Ma) to Recent. Here we present the first taxonomic description of new species of Paleogene owls from Asia, two new taxa from the Eocene and Oligocene of Mongolia. The anatomy of Heterostrix tatsinensis gen. et sp. nov., represented by a complete Early Oligocene tarsometatarsus, sheds light on the evolution of perching adaptations in these birds and expands the family diversity of this order. Eostrix tsaganica sp. nov. from the Early Eocene extend the known range of the protostrigid genus Eostrix into Asia (the other known species come from Europe and western North America). The paper also provides a review of the fossil record of owls, which gives evidence for the Late Cretaceous evolutionary radiation of this lineage. In spite of the absence of specimens from the Mesozoic, fossil owl collector-effort (since the 1860s) suggests that, in contrast to many other avian clades, the fossil record of these birds is complete enough for biological signal to be extracted