Atmospheric fluorescence is usually neglected in the reconstruction of the signals registered by Cherenkov telescopes, both IACTs and wide-angle detector arrays. In this paper we quantify the fluorescence contribution to the total light recorded in typical observational configurations. To this end we have implemented the production and tracking of fluorescence light in the CORSIKA code. Both the Cherenkov and fluorescence light distributions on ground (2200 m a.s.l.) have been simulated for gamma-ray showers in a wide energy range ($10^{-1} - 10^3$ TeV). The relative fluorescence contribution has been evaluated as a function of the shower energy and zenith angle. Our results indicate that at distances from the impact point smaller than 200 m the fluorescence contamination is negligible in both types of telescopes. However, at about 1000 m, the contamination in IACTs is around 5%. At these core distances, the signals recorded by wide-angle detectors contain around 45% of atmospheric fluorescence in the PeV region.
Developed as NASA Astrophysics Probe-class mission, the Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) is designed to identify the sources of ultra-high energy cosmic rays (UHECRs) and to observe cosmic neutrinos. POEMMA consists of two spacecraft flying in a loose formation at 525 km altitude, 28.5$^\circ$ inclination orbits. Each spacecraft hosts a Schmidt telescope with a large collecting area and wide Field-of-View (FoV). A novel focal plane is employed that is optimized to observe both the UV fluorescence signal from extensive air showers (EASs) and the optical Cherenkov signals f…
In the last ten years silicon photomultipliers (SiPMs) have gained terrain in experiments and applications in which photomultiplier tubes have been the dominant photosensors during decades. Imaging Atmospheric Cherenkov Telescopes (IACTs) for very high energy (VHE, E$>$50 GeV) gamma-ray astronomy are experiencing the same process. Until now FACT was the only IACT using SiPMs. In the Cherenkov Telescope Array (CTA), the next-generation VHE gamma-ray observatory, at least 70 telescopes equipped with SiPMs are planned to be built. The first prototypes have already been constructed and are now bei…
The Very High Energy source catalog at the ASI Science Data Center
当前一代切伦科夫望远镜发现的极高能（VHE）源数量的增加，使得专用源目录的创建以及多波长框架中VHE和较低能带数据的互相关变得特别重要。在ASI科学数据中心（ASDC）托管的“TeGeV目录”是由地基切伦科夫探测器探测到的VHE源的目录。TeGeVcat收集了所有关于观测到的GeV/TeV源的公开信息。该目录还包含有关公共光变曲线的信息，而可用的光谱数据则包含在可直接从TeGeV目录网页访问的ASDC SED Builder工具中。在这篇文章中，我们将报告目录和相关工具的全面描述。
This project is a study of VHE gamma ray astronomy using atmospheric Cherenkov technique. The project involved the study of processes of interaction of gamma rays, formation of extensive air showers, imaging of the Cherenkov radiation and data analysis of the observed data of Crab Nebula and MRK421 using TACTIC at Mt. Abu, India.
It has been established that Gamma-Ray Bursts (GRB) can produce Very High Energy radiation (E > 100 GeV), opening a new window on the investigation of particle acceleration and radiation properties in the most energetic domain. We expect that next-generation instruments, such as the Cherenkov Telescope Array (CTA), will mark a huge improvement in their observation. However, constraints on the target visibility and the limited duty cycle of Imaging Atmospheric Cherenkov Telescopes (IACT) reduce their ability to react promptly to transient events and to characterise their general properties. Her…
The Cherenkov Telescope Array (CTA) will be the next generation ground-based observatory for very-high-energy (VHE) gamma-ray astronomy, with the deployment of tens of highly sensitive and fast-reacting Cherenkov telescopes. It will cover a wide energy range (20 GeV - 300 TeV) with unprecedented sensitivity. To maximize the scientific return, the observatory will be provided with an online software system that will perform the first analysis of scientific data in real-time. This study investigates the precision and accuracy of available science tools and analysis techniques for the short-term …
Two of the Key Science Projects of the Cherenkov Telescope Array (CTA) consist in performing a deep survey of the Galactic and Extragalactic sky, providing an unbiased view of the Universe at energies above tens of GeV. To optimize the time spent to perform the Extragalactic survey, a so-called "divergent mode" of the CTA was proposed as an alternative observation strategy to the traditional parallel pointing in order to increase its instantaneous field of view. The search for transient VHE sources would also benefit from an extended field of view. In the divergent mode, each telescope points …
We will describe the current status of the ASTRI Mini-Array, under construction at the Teide Astronomical Observatory in Tenerife, Spain. The final layout of the array will include nine small Cherenkov telescopes covering an area of about 650 x 270 square meters. The ASTRI telescopes adopt a dual-mirror Schwarzchild-Couder aplanatic optical design. In the focal plane, the ASTRI camera, based on silicon photo-multiplier detectors, will cover a large field-of-view ( > 10 deg in diameter). This system also provides good gamma-ray sensitivity at very high energies (VHE, above 10 TeV) combined with…
Neutrino Telescope Array Letter of Intent: A Large Array of High Resolution Imaging Atmospheric Cherenkov and Fluorescence Detectors for Survey of Air-showers from Cosmic Tau Neutrinos in the PeV-EeV Energy Range
本意向书（LoI）描述了中微子望远镜阵列（NTA）项目的大纲和计划。高能中微子为强子加速提供了独特而无可争辩的证据。最近，冰立方已经报道了超过预期的来自大气秒的天文中微子候选者，但受到水切伦科夫探测方法的限制。下一代高能中微子望远镜应该能够为宇宙高能中微子建立无可争辩的证据。它不仅应该有数量级的更大的灵敏度，而且还应该有足够的指向精度来探测已知或未知的天文物体，而不会受到大气层的影响。拟议的装置是一个大型阵列的成像大气切伦科夫和荧光探测器的复眼站，具有宽视场和精细的观测能力，从PeV-EeV能量范围的宇宙τ中微子的空气簇射。这套先进的光学复杂系统主要是在全天空巡天高分辨率空气簇射探测器（Ashra）的基础上发展起来的，并采用τ簇射掠地方法对PeV-EeV τ中微子进行巡天。在标准GRB中微子注量的条件下，它可以对PeV-EeV τ中微子进行宽（30 ° x 360 °）和深（~400 Mpc）的巡天观测，而且在基本无背景的条件下，它的指向精度优于0.2 °。通过在宽视场中对掠地τ阵雨进行先进成像，我们的目标是明确发现和识别天文τ中微子源，为天体物理强子模型提供不可逃避的证据，以加速和/或在精确确定的方向上传播极高能量的质子。
The Cherenkov Telescope Array (CTA) will be the leading ground-base observatory for Very High Energy (VHE) γ-ray astronomy for the next decades. Its southern site will host about 70 Small Sized Telescopes (SSTs) which will determine the CTA sensitivity at γ-ray energies between 1 and 300 TeV. One of the design options for the SST cameras is the silicon photomultiplier-based Compact High-Energy Camera (CHEC-S). The back-end electronics (BEE) of CHEC-S interconnects the camera front-end modules, provides power and clock distribution, aggregation, routing and time stamping of data and most import…
The Fluorescence Telescope is one of the two telescopes on board the Extreme Universe Space Observatory on a Super Pressure Balloon II (EUSO-SPB2). EUSO-SPB2 is an ultra-long-duration balloon mission that aims at the detection of Ultra High Energy Cosmic Rays (UHECR) via the fluorescence technique (using a Fluorescence Telescope) and of Ultra High Energy (UHE) neutrinos via Cherenkov emission (using a Cherenkov Telescope). The mission is planned to fly in 2023 and is a precursor of the Probe of Extreme Multi-Messenger Astrophysics (POEMMA). The Fluorescence Telescope is a second generation ins…
The CoMET R&D project focuses on the development of a new technique for the observation of very high-energy (VHE) $γ$-rays from the ground at energies above ~200 GeV, thus covering emission from soft-spectrum sources. The CoMET array under study combines 1242 particle detector units, distributed over a circular area of ~160 m in diameter and placed at a very high altitude (5.1 km), with atmospheric Cherenkov light detectors. The atmospheric Cherenkov light detectors, inspired by the "HiSCORE" design and improved for the energy range of interest, can be operated together with the particle detec…
Very High Energy (VHE) gamma rays constitute one of the main pillars of high energy astrophysics. Gamma rays are produced under extreme relativistic conditions in the Universe. VHE gamma$ rays can be detected indirectly on the ground. Detection of these energetic photons poses several technological challenges. Firstly, even though gamma rays are highly penetrative, the Earth's atmosphere is opaque to them. Secondly, these gamma rays are to be detected against the overwhelming background of cosmic rays. When a VHE gamma ray arrives at the top of the atmosphere it produces charged secondaries. T…
The Extreme Universe Space Observatory on a Super Pressure Balloon II (EUSO-SPB2) is a second generation stratospheric balloon instrument for the detection of Ultra High Energy Cosmic Rays (UHECRs, E > 1 EeV) via the fluorescence technique and of Very High Energy (VHE, E > 10 PeV) neutrinos via Cherenkov emission. EUSO-SPB2 is a pathfinder mission for instruments like the proposed Probe Of Extreme Multi-Messenger Astrophysics (POEMMA). The purpose of such a space-based observatory is to measure UHECRs and UHE neutrinos with high statistics and uniform exposure. EUSO-SPB2 is designed with two S…
The Cherenkov light produced in air showers largely contributes to the signal observed in ground-based gamma-ray and cosmic-ray observatories. Yet, no description of this phenomenon is available covering both regions of small and large angles to the shower axis. To fill this gap, a parametrization of the angular distribution of Cherenkov photons is performed in terms of a physically-motivated parametric function. Model parameters are constrained using simulated gamma-ray and proton showers with energies in the TeV to EeV region. As a result, a new parametrization is obtained that improves the …
Cosmic-ray observatories necessarily rely on Monte Carlo simulations for their design, calibration and analysis of their data. Detailed simulations are very demanding computationally. We present a python-based package called ShowerModel to model cosmic-ray showers, their light production and their detection by an array of telescopes. It is based on parameterizations of both Cherenkov and fluorescence emission in cosmic-ray induced air showers. The package permits the modelling of fluorescence telescopes, imaging air Cherenkov telescopes, wide-angle Cherenkov detectors or any hybrid design. Sho…
The Cherenkov Telescope Array (CTA) project, led by an international collaboration of institutes, aims to create the world's largest next generation observatory for Very High Energy (VHE) gamma-ray astronomy. It will be devoted to observations in a wide band of energy, from a few tens of GeV to a few hundreds of TeV with Large, Medium and Small-sized telescopes. The Small-Size Telescopes (SSTs) are dedicated to the highest energy range above a few TeV and up to 300 TeV. GCT is an imaging atmospheric Cherenkov telescope (IACT) proposed for the subarray of about 70 SSTs to be installed on the So…
