25,257 research outputs found
Cherenkov Telescope Array : the World’s largest VHE gamma-ray observatory
No full textVery-High Energy (VHE) gamma-ray astroparticle physics is a relatively young field, and observations over the past decade have surprisingly revealed almost two hundred VHE emitters which appear to act as cosmic particle accelerators. These sources are an important component of the Universe, influencing the evolution of stars and galaxies. At the same time, they also act as a probe of physics in the most extreme environments known - such as in supernova explosions, and around or after the merging of black holes and neutron stars. However, the existing experiments have provided exciting glimpses, but often falling short of supplying the full answer. A deeper understanding of the TeV sky requires a significant improvement in sensitivity at TeV energies, a wider energy coverage from tens of GeV to hundreds of TeV and a much better angular and energy resolution with respect to the currently running facilities. The next generation gamma-ray observatory, the Cherenkov Telescope Array Observatory (CTAO), is the answer to this need. In this talk I will present this upcoming observatory from its design to the construction, and its potential science exploitation. CTAO will allow the entire astronomical community to explore a new discovery space that will likely lead to paradigm changing breakthroughs. In particular, CTA has an unprecedented sensitivity to short (sub-minute) timescale phenomena, placing it as a key instrument in the future of multi-messenger and multi-wavelength time domain astronomy. I will conclude the talk presenting the first scientific results obtained by the LST-1, the prototype of one CTA telescope type - the Large Sized Telescope, that is currently under commission
Cross-calibration and combined analysis of the CTA-LST prototype and the MAGIC telescopes
No full textThe Cherenkov Telescope Array (CTA) is the next-generation gamma-ray observatory that is
expected to reach one order of magnitude better sensitivity than that of current telescope arrays.
The Large-Sized Telescopes (LSTs) have an essential role in extending the energy range down to
20 GeV. The prototype LST (LST-1) proposed for CTA was built in La Palma, the northern site
of CTA, in 2018. LST-1 is currently in its commissioning phase and moving towards scientific
observations. The LST-1 camera consists of 1855 photomultiplier tubes (PMTs) which are
sensitive to Cherenkov light. PMT signals are recorded as waveforms sampled at 1 GHz rate with
Domino Ring Sampler version 4 (DRS4) chips. Fast sampling is essential to achieve a low energy
threshold by minimizing the integration of background light from the night sky. Absolute charge
calibration can be performed by the so-called F-factor method, which allows calibration constants
to be monitored even during observations. A calibration pipeline of the camera readout has been
developed as part of the LST analysis chain. The pipeline performs DRS4 pedestal and timing
corrections, as well as the extraction and calibration of charge and time of pulses for subsequent
higher-level analysis. The performance of each calibration step is examined, and especially charge
and time resolution of the camera readout are evaluated and compared to CTA requirements. We
report on the current status of the calibration pipeline, including the performance of each step
through to signal reconstruction, and the consistency with Monte Carlo simulation
A fast muon tagger method for Imaging Atmospheric Cherenkov Telescopes
No full textThe Cherenkov Telescope Array (CTA) will be the next major observatory for Very High Energy (VHE) γ-ray astronomy. Its optical throughput calibration relies on muon Cherenkov rings. This work is aimed at developing a fast and efficient muon tagger at the camera level for the CTA telescopes. A novel technique to tag muons using the capabilities of silicon photomultiplier Compact High-Energy Camera CHEC-S, one of the design options for the camera of the Small Size Telescopes (SSTs), has been developed, studying and comparing different algorithms such as circle fitting, machine learning and simple pixel counting. Their performance in terms of efficiency and computation speed was investigated using simulations with varying levels of night sky background light. The application of the best performing method to the Large Size Telescope (LST) camera has been also studied, with the goal of improving the speed of the muon preselection
Knowledge for Development
No full textMetadata only recordThis website, established by the Technical Centre for Agricultural and Rural Cooperation (CTA), serves as an open forum for professionals, stakeholders, policy makers, farmers, and researchers in the field of agriculture to share information about initiatives, studies, and results in order to facilitate collaboration concerning policy development with the greater goal of assisting the development, adaptation, and adoption of science and technology in agriculture in African, Caribbean, and Pacific nations
Cross-calibration and combined analysis of the CTA-LST prototype and the MAGIC telescopes
No full textThe Cherenkov Telescope Array (CTA) will be the next generation gamma-ray observatory, which will consist of three kinds of telescopes of different sizes. Among those, the Large Size Telescope (LST) will be the most sensitive in the low energy range starting from 20 GeV. The prototype LST (LST-1) proposed for CTA was inaugurated in October 2018 in the northern hemisphere site, La Palma (Spain), and is currently in its commissioning phase. MAGIC is a system of two gamma-ray Cherenkov telescopes of the current generation, located approximately 100 m away from LST-1, that have been operating in stereoscopic mode since 2009. Since LST-1 and MAGIC can observe the same air shower events, we can compare the brightness of showers, estimated energies of gamma rays, and other parameters event by event, which can be used to cross-calibrate the telescopes. Ultimately, by performing combined analyses of the events triggering the three telescopes, we can reconstruct the shower geometry more accurately, leading to better energy and angular resolutions, and a better discrimination of the background showers initiated by cosmic rays. For that purpose, as part of the commissioning of LST-1, we performed joint observations of established gamma-ray sources with LST-1 and MAGIC. Also, we have developed Monte Carlo simulations for such joint observations and an analysis pipeline which finds event coincidence in the offline analysis based on their timestamps. In this work, we present the first detection of an astronomical source, the Crab Nebula, with combined observation of LST-1 and MAGIC. Moreover, we show results of the inter-telescope cross-calibration obtained using Crab Nebula data taken during joint observations with LST-1 and MAGIC
HAWC J2227+610: a potential PeVatron candidate for the CTA in the northern hemisphere [Elektronisk resurs]
No full textRecent observations of the gamma-ray source HAWC J2227+610 by Tibet AS+MD and LHAASO confirm the special interest of this source as a galactic PeVatron candidate in the northern hemisphere. HAWC J2227+610 emits Very High Energy (VHE) gamma-rays up to 500 TeV, from a region coincident with molecular clouds and significantly displaced from the nearby pulsar J2229+6114. Even if this morphology favours an hadronic origin, both leptonic or hadronic models can describe the current VHE gamma-ray emission. The morphology of the source is not well constrained by the present measurements and a better characterisation would greatly help the understanding of the underlying particle acceleration mechanisms. The Cherenkov Telescope Array (CTA) will be the future most sensitive Imaging Atmospheric Cherenkov Telescope and, thanks to its unprecedented angular resolution, could contribute to better constrain the nature of this source. The present work investigates the potentiality of CTA to study the morphology and the spectrum of HAWC J2227+610. For this aim, the source is simulated assuming the hadronic model proposed by the Tibet AS+MD collaboration, recently fitted on multi-wavelength data, and two spatial templates associated to the source nearby molecular clouds. Different CTA layouts and observation times are considered. A 3D map based analysis shows that CTA is able to significantly detect the extension of the source and to attribute higher detection significance to the simulated molecular cloud template compared to the alternative one. CTA data does not allow to disentangle the hadronic and the leptonic emission models. However, it permits to correctly reproduce the simulated parent proton spectrum characterized by a ∼ 500 TeV cutoff. © Copyright owned by the author(s) under the terms of the Creative Commons
Performance of the joint LST-1 and MAGIC observations evaluated with Crab Nebula data
No full textAims. Large-Sized Telescope 1 (LST-1), the prototype for the Large-Sized Telescope at the upcoming Cherenkov Telescope Array Observatory, is concluding its commissioning phase at the Observatorio del Roque de los Muchachos on the island of La Palma. The proximity of LST-1 to the two MAGIC (Major Atmospheric Gamma Imaging Cherenkov) telescopes makes it possible to carry out observations of the same gamma-ray events with both systems.
Methods. We describe the joint LST-1+MAGIC analysis pipeline and used simultaneous Crab Nebula observations and Monte Carlo simulations to assess the performance of the three-telescope system. The addition of the LST-1 telescope allows for the recovery of events in which one of the MAGIC images is too dim to survive analysis quality cuts.
Results. Thanks to the resulting increase in the collection area and stronger background rejection, we found a significant improvement in sensitivity, allowing for the detection of 30% weaker fluxes in the energy range between 200 GeV and 3 TeV. The spectrum of the Crab Nebula, reconstructed in the energy range between similar to 60 GeV and similar to 10 TeV, is in agreement with previous measurements
The Structure of Scientific Collaboration Networks in Scientometrics
No full textThe structure of scientific collaboration networks in scientometrics was investigated at the level of individuals by using bibliographic data of all papers published in the international journal Scientometrics retrieved from the Science Citation Index (SCI) during 1978 to 2004. Combined analysis of social network analysis (SNA), co-occurrence analysis, cluster analysis and frequency analysis of words was explored to reveal: (1) The microstructure of the collaboration network on scientists’ aspects of scientometrics; (2) The major collaborative fields of the collaborative sub-networks; (3) The collaborative center of the collaboration network in scientometrics
HAWC J2227+610: a potential PeVatron candidate for the CTA in the northern hemisphere
No full textInternational audienceRecent observations of the gamma-ray source HAWC J2227+610 by Tibet AS+MD and LHAASOconfirm the special interest of this source as a galactic PeVatron candidate in the northern hemisphere. HAWC J2227+610 emits Very High Energy (VHE) gamma-rays up to 500 TeV, froma region coincident with molecular clouds and significantly displaced from the nearby pulsarJ2229+6114. Even if this morphology favours an hadronic origin, both leptonic or hadronicmodels can describe the current VHE gamma-ray emission. The morphology of the source is notwell constrained by the present measurements and a better characterisation would greatly helpthe understanding of the underlying particle acceleration mechanisms. The Cherenkov TelescopeArray (CTA) will be the future most sensitive Imaging Atmospheric Cherenkov Telescope and,thanks to its unprecedented angular resolution, could contribute to better constrain the nature ofthis source. The present work investigates the potentiality of CTA to study the morphology andthe spectrum of HAWC J2227+610. For this aim, the source is simulated assuming the hadronicmodel proposed by the Tibet AS+MD collaboration, recently fitted on multi-wavelength data, andtwo spatial templates associated to the source nearby molecular clouds. Different CTA layouts andobservation times are considered. A 3D map based analysis shows that CTA is able to significantlydetect the extension of the source and to attribute higher detection significance to the simulatedmolecular cloud template compared to the alternative one. CTA data does not allow to disentanglethe hadronic and the leptonic emission models. However, it permits to correctly reproduce thesimulated parent proton spectrum characterized by a ∼ 500 TeV cutoff
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