Imaging atmospheric Cherenkov telescopes (IACTs) such as the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes endeavor to reach the lowest possible energy threshold. In doing so the trigger system is a key element. Reducing the trigger threshold is hampered by the rapid increase of accidental triggers generated by ambient light, the so-called Night Sky Background (NSB). In this paper we present a topological trigger, dubbed Topo-trigger, which rejects events on the basis of their relative orientation in the telescope cameras. We have simulated and tested the trigger selection algorithm in the MAGIC telescopes. The algorithm was tested using MonteCarlo simulations and shows a rejection of 85% of the accidental stereo triggers while preserving 99 % of the gamma rays. A full implementation of this trigger system would achieve an increase in collection area between 10 and 20% at the energy threshold. The analysis energy threshold of the instrument is expected to decrease by ~8 %. The selection algorithm was tested on real MAGIC data taken with the current trigger configuration and no $γ$-like events were found to be lost.
This paper is concerned with the performance optimisation of an stereoscopic array of imaging atmospheric Cherenkov telescopes (IACTs) as a function of their positioning on the ground. In this first work we are concerned primarily with the study of the optimisation method and its test on toy arrays of few (3-6) telescopes. The ideas presented here were developed to investigate alternative ways of studying IACT array geometries. The proposal is an attempt to cover more exhaustively and systematically the parameter space involved in the design of a stereoscopic IACT array, aiming to develop a su…
The Cherenkov Telescope Array (CTA), conceived as an array of tens of imaging atmospheric Cherenkov telescopes (IACTs), is an international project for a next-generation ground-based gamma-ray observatory, aiming to improve on the sensitivity of current-generation instruments a factor of five to ten and provide energy coverage from 20 GeV to more than 300 TeV. Arrays of IACTs probe the very-high-energy gamma-ray sky. Their working principle consists of the simultaneous observation of air showers initiated by the interaction of very-high-energy gamma rays and cosmic rays with the atmosphere. Ch…
Cherenkov Telescope Array (CTA) is an upcoming instrument that will start a new generation of atmospheric Cherenkov telescopes. CTA is expected not only to provide an unprecedented sensitivity in the tens of GeV to hundreds of TeV range, but also to considerably improve the systematic uncertainties of the measurements. We study the images registered by Cherenkov telescopes from low energy gamma rays with its first interaction in the upper parts of the atmosphere. The images show a characteristic separation due to the deflection of the first e- e+ pair in the Geomagnetic Field. We evaluate the …
The Topo-trigger: A new stereo trigger for lowering the energy threshold of IACTs
在这篇文章中提出的硬件的目的是降低MAGIC望远镜的能量阈值，而不显着增加数据采集速率。为了实现这一目的，我们开发了一个额外的触发级别，它依赖于两个MAGIC相机中发出触发的位置，以排除意外事件。这允许降低鉴别器阈值（DT），从而导致仪器的能量阈值降低。我们使用标准的MAGIC Monte Carlo（MC）模拟了地形触发的概念，并使用真实的望远镜数据进行了测试。在本文中，我们展示了这些测试的概念和结果。
The High Energy Stereoscopic System (H.E.S.S.) is one of the three arrays of imaging atmospheric Cherenkov telescopes (IACTs) currently in operation. It is composed of four 12-meter telescopes and a 28-meter one, and is sensitive to gamma rays in the energy range ~30 GeV - 100 TeV. The cameras of the 12-m telescopes recently underwent a substantial upgrade, with the goal of improving their performance and robustness. The upgrade involved replacing all camera components except for the photomultiplier tubes (PMTs). This meant developing new hardware for the trigger, readout, power, cooling and m…
Irkutsk State University（伊尔库茨克国立大学）；Lomonosov Moscow State University（罗蒙诺索夫莫斯科国立大学）
Imaging Atmospheric Cherenkov Telescopes (IACT) of TAIGA astrophysical complex allow to observe high energy gamma radiation helping to study many astrophysical objects and processes. TAIGA-IACT enables us to select gamma quanta from the total cosmic radiation flux and recover their primary parameters, such as energy and direction of arrival. The traditional method of processing the resulting images is an image parameterization - so-called the Hillas parameters method. At the present time Machine Learning methods, in particular Deep Learning methods have become actively used for IACT image proc…
Deep convolutional neural networks (DCNs) are a promising machine learning technique to reconstruct events recorded by imaging atmospheric Cherenkov telescopes (IACTs), but require optimization to reach full performance. One of the most pressing challenges is processing raw images captured by cameras made of hexagonal lattices of photo-multipliers, a common layout among IACT cameras which topologically differs from the square lattices conventionally expected, as their input data, by DCN models. Strategies directed to tackle this challenge range from the conversion of the hexagonal lattices ont…
The High Energy Stereoscopic System (H.E.S.S.) is an array of five imaging atmospheric Cherenkov telescopes in Namibia observing gamma-rays in the energy range from a few tens of GeV to a few tens of TeV. The Cherenkov signal detected by photomultiplier tubes is sampled at 1 GHz. In nominal data acquisition (charge) mode, this signal is integrated over a fixed window of 16 ns in case trigger conditions are met. Thanks to the electronics upgrade of the four H.E.S.S. I cameras in spring 2017, full 1 GHz-sampled waveforms can be read out in parallel to the nominal charge mode. This allows for a h…
The Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescope system is located on the Canary Island of La Palma and inspects the very high-energy (VHE, few tens of GeV and above) gamma-ray sky. MAGIC consists of two imaging atmospheric Cherenkov telescopes (IACTs), which capture images of the air showers originating from the absorption of gamma rays and cosmic rays by the atmosphere, through the detection of Cherenkov photons emitted in the shower. The sensitivity of IACTs to gamma-ray sources is mainly determined by the ability to reconstruct the properties (type, energy, and arrival direc…
Enhancing the Angular Resolution of Large Array of imaging atmospheric Cherenkov Telescope (LACT) at Ultra-High Energies
University of Science and Technology of China（中国科学技术大学）；Institute of High Energy Physics（高能物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Tianfu Cosmic Ray Research Center（天府宇宙线研究中心）
Prospects for the detection of gamma rays using Cherenkov telescopes enhanced by a ground array observatory
FZU - Institute of Physics of the Czech Academy of Sciences（捷克科学院物理研究所）；Pidstryhach Institute for Applied Problems of Mechanics and Mathematics, National Academy of Sciences of Ukraine（乌克兰国家科学院皮德斯特雷哈赫应用力学与数学问题研究所）；Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（波兰科学院尼古拉·哥白尼天文中心）；Institute of Nuclear Physics, Polish Academy of Sciences（波兰科学院核物理研究所）；Astronomical Observatory, University of Warsaw（华沙大学天文台）；Astronomical Institute of the Czech Academy of Sciences（捷克科学院天文研究所）；ETH Zurich, Institute for Particle Physics and Astrophysics（苏黎世联邦理工学院粒子物理与天体物理研究所）；Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University（查理大学数学与物理学院粒子与核物理研究所）；Astronomical Observatory, Jagiellonian University（雅盖隆大学天文台）
The High Energy Stereoscopic System (H.E.S.S.) is an array of five Imaging Atmospheric Cherenkov Telescopes located in the Khomas Highland of Namibia. H.E.S.S. observes gamma rays above tens of GeV by detecting the Cherenkov light that is produced when Very High Energy gamma rays interact with the Earth's atmosphere. The H.E.S.S. Data Acquisition System (DAQ) coordinates the nightly telescope operations, ensuring that the various components communicate properly and behave as intended. It also provides the interface between the telescopes and the people on shift who guide the operations. The DA…
