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3. Intermediate fluence downward terrestrial gamma ray flashes as observed by the Telescope Array Surface DetectorR. U. Abbasi, N. Kieu, P. R. Krehbiel, J. W. Belz, M. M. F. Saba, W. Rison, M. A. Stanley, D. Rodeheffer, D. Mazzucco, Jon Paul Lundquist, 2024, original scientific article Abstract: On 11 September 2021, two small thunderstorms developed over the Telescope Array Surface Detector (TASD) that produced an unprecedented number of six downward terrestrial gamma ray flashes (TGFs) within one‐hour timeframe. The TGFs occurred during the initial stage of negative cloud‐to‐ground flashes whose return strokes had increasingly large peak currents up to 223 kA, 147 GeV energy deposit in up to 25 1.2 km‐spaced surface detectors, and intermittent bursts of gamma‐rays with total durations up to 717 s. The analyses are based on observations recorded by the TASD network, complemented by data from a 3D lightning mapping array, broadband VHF interferometer, fast electric field change sensor, high‐speed video camera, and the National Lightning Detection Network. The TGFs of the final two flashes had gamma fluences of and 8, logarithmically bridging the gap between previous TASD and satellite‐based detections. The observations further emphasize the similarity between upward and downward TGF varieties, suggesting a common mechanism for their production.
Keywords: Telescope Array Surface Detector, terrestrial gamma ray flashes, 3D lightning mapping array, broadband VHF interferometer, fast electric field change sensor, high‐speed video camera, National Lightning Detection Network, TGF fluence measurement
Published in RUNG: 23.04.2025; Views: 280; Downloads: 4
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4. Algebraic structures and graph theoryscientific monograph Keywords: groups, ring, field, lattice, hypergroups, hyperring, hyperfield, graph, hypergraph, equivalence relation, operation, hyperoperation
Published in RUNG: 04.03.2025; Views: 605; Downloads: 5
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7. Multi-layer palladium diselenide as a contact material for two-dimensional tungsten diselenide field-effect transistorsGennadiy Murastov, Muhammad Awais Aslam, Simon Leitner, Vadym Tkachuk, Iva Plutnarová, Egon Pavlica, Raul D. Rodriguez, Zdeněk Sofer, Aleksandar Matković, 2024, original scientific article Abstract: Tungsten diselenide (WSe2) has emerged as a promising ambipolar semiconductor material for field-effect transistors (FETs) due to its unique electronic properties, including a sizeable band gap, high carrier mobility, and remarkable on–off ratio. However, engineering the contacts to WSe2 remains an issue, and high contact barriers prevent the utilization of the full performance in electronic applications. Furthermore, it could be possible to tune the contacts to WSe2 for effective electron or hole injection and consequently pin the threshold voltage to either conduction or valence band. This would be the way to achieve complementary metal–oxide–semiconductor devices without doping of the channel material.This study investigates the behaviour of two-dimensional WSe2 field-effect transistors with multi-layer palladium diselenide (PdSe2) as a contact material. We demonstrate that PdSe2 contacts favour hole injection while preserving the ambipolar nature of the channel material. This consequently yields high-performance p-type WSe2 devices with PdSe2 van der Waals contacts. Further, we explore the tunability of the contact interface by selective laser alteration of the WSe2 under the contacts, enabling pinning of the threshold voltage to the valence band of WSe2, yielding pure p-type operation of the devices.
Keywords: field-effect transistor, tungsten diselenide, van der Waals, two-dimensional materials
Published in RUNG: 29.05.2024; Views: 2132; Downloads: 11
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9. Effects of Galactic magnetic field on the UHECR anisotropy studiesR. Higuchi, Jon Paul Lundquist, 2022, published scientific conference contribution Abstract: Telescope Array (TA) and Auger experiments reported anisotropies in the arrival direction of ultrahigh-energy cosmic rays (UHECRs). In particular, Auger Collaboration reported a correlation
between UHECR events and the flux model of assumed sources and suggested a contribution of
starburst galaxies (SBGs) to the anisotropy of UHECRs. However, in their study, the effect of
coherent deflections by the galactic magnetic field (GMF) is not taken into account. In this study, we investigated the effect of the GMF on the arrival directions of UHECRs using the cosmic ray propagation code CRPropa3. We used a backtracking technique which consists of propagating antiparticles to map the flux outside the galaxy to at the earth. We estimate the systematic effects caused by GMF in the reported likelihood analysis. We conduct likelihood analysis for mock UHECR datasets based on the flux pattern through the GMF model. We found systematic decrease of (f_ani, �) due to GMF. As prospects for the TAx4 experiment and joint analysis of Auger and TA collaborations, we develop the likelihood analysis method with the convolution of the rigidity spectrum.
Keywords: Telescope Array, TAx4, ultra-high energy, cosmic rays, anisotropy, galactic magnetic field, starburst galaxies
Published in RUNG: 29.09.2023; Views: 1943; Downloads: 6
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