868 research outputs found
Second large-scale Monte Carlo study for the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) represents the next generation of ground
based instruments for Very High Energy gamma-ray astronomy. It is expected to
improve on the sensitivity of current instruments by an order of magnitude and
provide energy coverage from 20 GeV to more than 200 TeV. In order to achieve
these ambitious goals Monte Carlo (MC) simulations play a crucial role, guiding
the design of CTA. Here, results of the second large-scale MC production are
reported, providing a realistic estimation of feasible array candidates for
both Northern and Sourthern Hemisphere sites performance, placing CTA
capabilities into the context of the current generation of High Energy
-ray detectors.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Monte Carlo Performance Studies of Candidate Sites for the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) is the next-generation gamma-ray
observatory with sensitivity in the energy range from 20 GeV to beyond 300 TeV.
CTA is proposed to consist of two arrays of 40-100 imaging atmospheric
Cherenkov telescopes, with one site located in each of the Northern and
Southern Hemispheres. The evaluation process for the candidate sites for CTA is
supported by detailed Monte Carlo simulations, which take different attributes
like site altitude and geomagnetic field configuration into account. In this
contribution we present the comparison of the sensitivity and performance of
the different CTA site candidates for the measurement of very-high energy gamma
rays.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Plasduino: an inexpensive, general purpose data acquisition framework for educational experiments
Based on the Arduino development platform, Plasduino is an open-source data
acquisition framework specifically designed for educational physics
experiments. The source code, schematics and documentation are in the public
domain under a GPL license and the system, streamlined for low cost and ease of
use, can be replicated on the scale of a typical didactic lab with minimal
effort. We describe the basic architecture of the system and illustrate its
potential with some real-life examples.Comment: 11 pages, 10 figures, presented at the XCIX conference of the
Societ\`a Italiana di Fisic
Monte Carlo Performance Studies for the Site Selection of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) represents the next generation of
ground-based instruments for very-high-energy (VHE) gamma-ray astronomy, aimed
at improving on the sensitivity of current-generation experiments by an order
of magnitude and providing coverage over four decades of energy. The current
CTA design consists of two arrays of tens of imaging atmospheric Cherenkov
telescopes, comprising Small, Medium and Large-Sized Telescopes, with one array
located in each of the Northern and Southern Hemispheres. To study the effect
of the site choice on the overall \gls{cta} performance and support the site
evaluation process, detailed Monte Carlo simulations have been performed. These
results show the impact of different site-related attributes such as altitude,
night-sky background and local geomagnetic field on CTA performance for the
observation of VHE gamma rays.Comment: 34 pages, 11 figures, Accepted for publication in AP
Structural transitions in the RNA 7SK 5' hairpin and their effect on HEXIM binding.
7SK RNA, as part of the 7SK ribonucleoprotein complex, is crucial to the regulation of transcription by RNA-polymerase II, via its interaction with the positive transcription elongation factor P-TEFb. The interaction is induced by binding of the protein HEXIM to the 5' hairpin (HP1) of 7SK RNA. Four distinct structural models have been obtained experimentally for HP1. Here, we employ computational methods to investigate the relative stability of these structures, transitions between them, and the effects of mutations on the observed structural ensembles. We further analyse the results with respect to mutational binding assays, and hypothesize a mechanism for HEXIM binding. Our results indicate that the dominant structure in the wild type exhibits a triplet involving the unpaired nucleotide U40 and the base pair A43-U66 in the GAUC/GAUC repeat. This conformation leads to an open major groove with enough potential binding sites for peptide recognition. Sequence mutations of the RNA change the relative stability of the different structural ensembles. Binding affinity is consequently lost if these changes alter the dominant structure
Data model issues in the Cherenkov Telescope Array project
The planned Cherenkov Telescope Array (CTA), a future ground-based
Very-High-Energy (VHE) gamma-ray observatory, will be the largest project of
its kind. It aims to provide an order of magnitude increase in sensitivity
compared to currently operating VHE experiments and open access to guest
observers. These features, together with the thirty years lifetime planned for
the installation, impose severe constraints on the data model currently being
developed for the project.
In this contribution we analyze the challenges faced by the CTA data model
development and present the requirements imposed to face them. While the full
data model is still not completed we show the organization of the work, status
of the design, and an overview of the prototyping efforts carried out so far.
We also show examples of specific aspects of the data model currently under
development.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
The Cherenkov Telescope Array Performance in Divergent Mode
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 to a
position in the sky that is slightly offset, in the outward direction, from the
center of the field of view. In this contribution, we present the first
performance estimation from full Monte Carlo simulation of possible CTA
divergent mode setups
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