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Opis: 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.
Najdeno v: ključnih besedah
Ključne besede: Pierre Auger Observatory, Auger Engineering Radio Array, atmospheric monitoring, lightning detectors
Objavljeno: 03.03.2016; Ogledov: 1945; Prenosov: 130
Polno besedilo (1,10 MB)

Opis: 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.
Najdeno v: ključnih besedah
Ključne besede: gamma rays, lightning, gamma ray bursts, surface detector
Objavljeno: 30.04.2020; Ogledov: 556; Prenosov: 0
Polno besedilo (1,14 MB)