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1.
Lightning Detection at the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Julian Rautenberg, 2015, published scientific conference contribution

Abstract: The Auger Engineering Radio Array, an extension of the Pierre Auger Observatory with antennas in the MHz range, requires to monitor the atmospheric conditions, which have a large influence on the radio emission of air showers. In particular, amplified signals up to an order of magnitude have been detected as an affect of thunderstorms. For a more detailed investigation and more generally, for detecting thunderstorms, a new lightning detection system has been installed at the Pierre Auger Observatory in Argentina. In addition, an electric-field mill measures the field strength on ground level at the antenna array. With these measurements, data periods affected by thunderstorms can be identified. Additionally, a lightning trigger for the water-Cherenkov detectors was developed to read out individual stations when a lightning was detected nearby. With these data, a possible correlation between the formation of lightning and cosmic rays can be investigated even at low energies of about 10[sup]15 eV. The structure and functionality of the lightning detection are described and first data analyses are shown.
Found in: ključnih besedah
Keywords: Pierre Auger Observatory, Auger Engineering Radio Array, atmospheric monitoring, lightning detectors
Published: 03.03.2016; Views: 2337; Downloads: 140
.pdf Fulltext (1,10 MB)

2.
3.
Gamma Ray Showers Observed at Ground Level in Coincidence With Downward Lightning Leaders
J. P. Lundquist, R.U. Abbasi, 2018, original scientific article

Abstract: Bursts of gamma ray showers have been observed in coincidence with downward propagating negative leaders in lightning flashes by the Telescope Array Surface Detector (TASD). The TASD is a 700‐km^2 cosmic ray observatory located in southwestern Utah, USA. In data collected between 2014 and 2016, correlated observations showing the structure and temporal development of three shower‐producing flashes were obtained with a 3‐D lightning mapping array, and electric field change measurements were obtained for an additional seven flashes, in both cases colocated with the TASD. National Lightning Detection Network information was also used throughout. The showers arrived in a sequence of 2–5 short‐duration (≤10 μs) bursts over time intervals of several hundred microseconds and originated at an altitude of ≃3–5 km above ground level during the first 1–2 ms of downward negative leader breakdown at the beginning of cloud‐to‐ground lightning flashes. The shower footprints, associated waveforms and the effect of atmospheric propagation indicate that the showers consist primarily of downward‐beamed gamma radiation. This has been supported by GEANT simulation studies, which indicate primary source fluxes of ≃10^12–10^14 photons for 16° half‐angle beams. We conclude that the showers are terrestrial gamma ray flashes, similar to those observed by satellites, but that the ground‐based observations are more representative of the temporal source activity and are also more sensitive than satellite observations, which detect only the most powerful terrestrial gamma ray flashes.
Found in: ključnih besedah
Keywords: gamma rays, lightning, gamma ray bursts, surface detector
Published: 30.04.2020; Views: 903; Downloads: 0
.pdf Fulltext (1,14 MB)

4.
The bursts of high energy events observed by the telescope array surface detector
J. P. Lundquist, R.U. Abbasi, 2017, original scientific article

Abstract: The Telescope Array (TA) experiment is designed to detect air showers induced by ultra high energy cosmic rays. The TA ground Surface particle Detector (TASD) observed several short-time bursts of air shower like events. These bursts are not likely due to chance coincidence between single shower events. The expectation of chance coincidence is less than 10^-4 for five-year's observation. We checked the correlation between these bursts of events and lightning data, and found evidence for correlations in timing and position. Some features of the burst events are similar to those of a normal cosmic ray air shower, and some are not. On this paper, we report the observed bursts of air shower like events and their correlation with lightning.
Found in: ključnih besedah
Summary of found: ...correlation between these bursts of events and lightning data, and found evidence for correlations in...
Keywords: High energy radiation, Lightning, Terrestrial gamma-ray flash
Published: 30.04.2020; Views: 813; Downloads: 0
.pdf Fulltext (1,70 MB)

5.
Observations of the origin of downward terrestrial gamma-ray flashes
M. A. Stanley, R. U. Abbasi, R. LeVon, W. Rison, D. Rodeheffer, T. Abu-Zayyad, Jon Paul Lundquist, P. R. Krehbiel, J. Remington, J. W. Belz, 2020, original scientific article

Abstract: In this paper we report the first close, high‐resolution observations of downward‐directed terrestrial gamma‐ray flashes (TGFs) detected by the large‐area Telescope Array cosmic ray observatory, obtained in conjunction with broadband VHF interferometer and fast electric field change measurements of the parent discharge. The results show that the TGFs occur during strong initial breakdown pulses (IBPs) in the first few milliseconds of negative cloud‐to‐ground and low‐altitude intracloud flashes and that the IBPs are produced by a newly identified streamer‐based discharge process called fast negative breakdown. The observations indicate the relativistic runaway electron avalanches (RREAs) responsible for producing the TGFs are initiated by embedded spark‐like transient conducting events (TCEs) within the fast streamer system and potentially also by individual fast streamers themselves. The TCEs are inferred to be the cause of impulsive sub‐pulses that are characteristic features of classic IBP sferics. Additional development of the avalanches would be facilitated by the enhanced electric field ahead of the advancing front of the fast negative breakdown. In addition to showing the nature of IBPs and their enigmatic sub‐pulses, the observations also provide a possible explanation for the unsolved question of how the streamer to leader transition occurs during the initial negative breakdown, namely, as a result of strong currents flowing in the final stage of successive IBPs, extending backward through both the IBP itself and the negative streamer breakdown preceding the IBP.
Found in: ključnih besedah
Summary of found: ...terrestrial gamma-ray flashes, lightning, fast breakdown, initial breakdown pulse, atmospheric electricity,...
Keywords: terrestrial gamma-ray flashes, lightning, fast breakdown, initial breakdown pulse, atmospheric electricity, transient conducting events
Published: 04.02.2021; Views: 374; Downloads: 2
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