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101.
102.
Effect of gamma irradiation on Schottky-contacted vertically aligned ZnO nanorod-based hydrogen sensor
Sapana Ranwa, Surendra Singh Barala, Mattia Fanetti, Mahesh Kumar, 2016, original scientific article

Abstract: We report the impact of gamma irradiation on the performance of a gold Schottky-contacted ZnO nanorod-based hydrogen sensor. RF-sputtered vertically aligned highly c-axis-oriented ZnO NRs were grown on Si(100) substrate. X-ray diffraction shows no significant change in crystal structure at low gamma doses from 1 to 5 kGy. As gamma irradiation doses increase to 10 kGy, the single crystalline ZnO structure converts to polycrystalline. The photoluminescence spectra also shows suppression of the near-band emission peak and the huge wide-band spectrum indicates the generation of structural defects at high gamma doses. At 1 kGy, the hydrogen sensor response was enhanced from 67% to 77% for 1% hydrogen in pure argon at a 150 °C operating temperature. However, at 10 kGy, the relative response decreases to 33.5%. High gamma irradiation causes displacement damage and defects in ZnO NRs, and as a result, degrades the sensor's performance as a result. Low gamma irradiation doses activate the ZnO NR surface through ionization, which enhances the sensor performance. The relative response of the hydrogen sensor was enhanced by ∼14.9% with respect to pristine ZnO using 1 kGy gamma ray treatment. © 2016 IOP Publishing Ltd.
Keywords: ZnO, nanorods, gamma irradiation, sensor
Published in RUNG: 12.01.2017; Views: 4206; Downloads: 0
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103.
High Energy Emission from Gamma Ray Bursts
Lili Yang, invited lecture at foreign university

Abstract: Gamma Ray Bursts (GRBs) are the most energetic explosions in the universe, and they have been proposed as the most promising candidate sources of ultra-high energy cosmic rays (UHECRs). As a result of interactions of UHECR within the host environment and during their propagation towards Earth, high energy neutrinos and photons are also expected from both prompt and afterglow emission. In this talk, I will review the standard theory of particle acceleration and production in a GRB fireball, and multi-wavelength and multi-messeger observations of GRB emission. I will present the prediction of PeV — EeV neutrino production and evidence of GeV gamma ray radiation, and the expected detection in IceCube, Pierre Auger Observatory and CTA (the next generation of Imaging Atmospheric Cherenkov Telescopes). The investigation of high-energy particles will provide insight into the nature and complicated mechanisms of GRBs.
Keywords: Gamma-Ray Bursts, high-energy emission, blastwave afterglow
Published in RUNG: 06.12.2016; Views: 4903; Downloads: 0
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FERMI-LAT OBSERVATIONS OF THE LIGO EVENT GW150914
Gabrijela Zaharijas, Collaboration Fermi LAT, Collaboration LIGO, 2016, original scientific article

Abstract: The Fermi Large Area Telescope (LAT) has an instantaneous field of view (FoV) covering ~1 5 of the sky and it completes a survey of the entire sky in high-energy gamma-rays every 3 hr. It enables searches for transient phenomena over timescales from milliseconds to years. Among these phenomena could be electromagnetic counterparts to gravitational wave (GW) sources. In this paper, we present a detailed study of the LAT observations relevant to Laser Interferometer Gravitational-wave Observatory (LIGO) event GW150914, which is the first direct detection of gravitational waves and has been interpreted as being due to the coalescence of two stellar-mass black holes. The localization region for GW150914 was outside the LAT FoV at the time of the GW signal. However, as part of routine survey observations, the LAT observed the entire LIGO localization region within ∼70 minutes of the trigger and thus enabled a comprehensive search for a γ-ray counterpart to GW150914. The study of the LAT data presented here did not find any potential counterparts to GW150914, but it did provide limits on the presence of a transient counterpart above 100 MeV on timescales of hours to days over the entire GW150914 localization region.
Keywords: gravitational waves, gamma rays
Published in RUNG: 20.06.2016; Views: 4678; Downloads: 0
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