37 research outputs found
Boosting the performance of the ASTRI SST-2M prototype: reflective and anti-reflective coatings
ASTRI is a Flagship Project of the Italian Ministry of Education, University
and Research, led by the Italian National Institute of Astrophysics, INAF. One
of the main aims of the ASTRI Project is the design, construction and
verification on-field of a dual mirror (2M) end-to-end prototype for the Small
Size Telescope (SST) envisaged to become part of the Cherenkov Telescope Array.
The ASTRI SST-2M prototype adopts the Schwarzschild-Couder design, and a camera
based on SiPM (Silicon Photo Multiplier); it will be assembled at the INAF
astronomical site of Serra La Nave on mount Etna (Catania, Italy) within mid
2014, and will start scientific validation phase soon after. The peculiarities
of the optical design and of the SiPM bandpass pushed towards specifically
optimized choices in terms of reflective coatings for both the primary and the
secondary mirror. In particular, multi-layer dielectric coatings, capable of
filtering out the large Night Sky Background contamination at wavelengths
nm have been developed and tested, as a solution for the
primary mirrors. Due to the conformation of the ASTRI SST-2M camera, a
reimaging system based on thin pyramidal light guides could be optionally
integrated aiming to increase the fill factor. An anti-reflective coating
optimized for a wide range of incident angles faraway from normality was
specifically developed to enhance the UV-optical transparency of these
elements. The issues, strategy, simulations and experimental results are
thoroughly presented.Comment: 4 pages, 6 figures. In Proceedings of the 33rd International Cosmic
Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All ASTRI contributions
at arXiv:1307.463
Volcanoes muon imaging using Cherenkov telescopes
A detailed understanding of a volcano inner structure is one of the
key-points for the volcanic hazards evaluation. To this aim, in the last
decade, geophysical radiography techniques using cosmic muon particles have
been proposed. By measuring the differential attenuation of the muon flux as a
function of the amount of rock crossed along different directions, it is
possible to determine the density distribution of the interior of a volcano. Up
to now, a number of experiments have been based on the detection of the muon
tracks crossing hodoscopes, made up of scintillators or nuclear emulsion
planes. Using telescopes based on the atmospheric Cherenkov imaging technique,
we propose a new approach to study the interior of volcanoes detecting the
Cherenkov light produced by relativistic cosmic-ray muons that survive after
crossing the volcano. The Cherenkov light produced along the muon path is
imaged as a typical annular pattern containing all the essential information to
reconstruct particle direction and energy. Our new approach offers the
advantage of a negligible background and an improved spatial resolution. To
test the feasibility of our new method, we have carried out simulations with a
toy-model based on the geometrical parameters of ASTRI SST-2M, i.e. the imaging
atmospheric Cherenkov telescope currently under installation onto the Etna
volcano. Comparing the results of our simulations with previous experiments
based on particle detectors, we gain at least a factor of 10 in sensitivity.
The result of this study shows that we resolve an empty cylinder with a radius
of about 100 m located inside a volcano in less than 4 days, which implies a
limit on the magma velocity of 5 m/h.Comment: 21 pages, 21 figures, in press on Nuclear Inst. and Methods in
Physics Research, A. Final version published online: 3-NOV-201
The DAQ system support to the AIV activities of the ASTRI camera proposed for the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA), the next generation ground-based observatory for very high-energy gamma rays, is being built and will be operated by an international consortium. Two arrays will be located in the northern and southern hemispheres. Each telescope array will operate different numbers and types of telescopes. The Italian National Institute for Astrophysics (INAF) is leading the ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) project in the framework of the small size class of telescopes (SST). A first goal of the ASTRI project is the realization of an end-to-end prototype in dual-mirror configuration (SST-2M). The ASTRI camera focal plane is composed of a matrix of silicon photo-multiplier sensors managed by innovative front-end and back-end electronics. The ASTRI SST2M prototype is installed in Italy at the INAF "M.G. Fracastoro" observing station located at Serra La Nave, 1735 m a.s.l. on Mount Etna, Sicily. The ASTRI Data AcQuisition (DAQ) system acquires, packet by packet, the camera data from the back-end electronics. The packets are then stored locally in one raw file as soon as they arrive. During the acquisition, the DAQ system groups the packets by data type (scientific, calibration, engineering) before processing and storing the data in FITS format. All the files are then transferred to the on-site archive. In addition, we implemented a quick-look component the allows the operator to display the camera data during the acquisition. A graphical user interface enables the operator to configure, monitor and control the DAQ software. Furthermore, we implemented the control panel algorithms within the framework of the Alma Common Software, in order to integrate the DAQ software within the ASTRI control software. The ASTRI DAQ system supports the camera AIV activities and operations. We provide the instrument workstation to support the AIV activities in the laboratory, and the camera server on-site. In this paper, we assess the ASTRI DAQ system as it has performed the AIV tasks for the ASTRI SST-2M prototype
The software architecture of the camera for the ASTRI SST-2M prototype for the Cherenkov Telescope Array
The purpose of this contribution is to present the current status of the software architecture of the ASTRI SST-2M Cherenkov Camera. The ASTRI SST-2M telescope is an end-to-end prototype for the Small Size Telescope of the Cherenkov Telescope Array. The ASTRI camera is an innovative instrument based on SiPM detectors and has several internal hardware components. In this contribution we will give a brief description of the hardware components of the camera of the ASTRI SST-2M prototype and of their interconnections. Then we will present the outcome of the software architectural design process that we carried out in order to identify the main structural components of the camera software system and the relationships among them. We will analyze the architectural model that describes how the camera software is organized as a set of communicating blocks. Finally, we will show where these blocks are deployed in the hardware components and how they interact. We will describe in some detail, the physical communication ports and external ancillary devices management, the high precision time-tag management, the fast data collection and the fast data exchange between different camera subsystems, and the interfacing with the external systems
The possibilities of Cherenkov telescopes to perform cosmic-ray muon imaging of volcanoes
Volcanic activity is regulated by the interaction of gas-liquid flow with conduit geometry. Hence, the quantitative understanding of the inner shallow structure of a volcano is mandatory to forecast the occurrence of dangerous stages of activity and mitigate volcanic hazards. Among the techniques used to investigate the underground structure of a volcano, muon imaging offers some advantages, as it provides a fine spatial resolution, and does not require neither spatially dense measurements in active zones, nor the implementation of cost demanding energizing systems, as when electric or active seismic sources are utilized. The principle of muon radiography is essentially the same as X-ray radiography: muons are more attenuated by higher density parts inside the target and thus information about its inner structure are obtained from the differential muon absorption. Up-to-date, muon imaging of volcanic structures has been mainly accomplished with detectors that employ planes of scintillator strips. These telescopes are exposed to different types of background noise (accidental coincidence of vertical shower particles, horizontal high-energy electrons, flux of upward going particles), whose amplitude is high relative to the tiny flux of interest. An alternative technique is based on the detection of the Cherenkov light produced by muons. The latter can be imaged as an annular pattern that contains the information needed to reconstruct both direction and energy of the particle. Cherenkov telescopes have never been utilized to perform muon imaging of volcanoes. Nonetheless, thanks to intrinsic features, they offer the possibility to detect the through-target muon flux with negligible levels of background noise. Under some circumstances, they would also provide a better spatial resolution and acceptance than scintillator-based telescopes. Furthermore, contrarily to the latter systems, Cherenkov detectors allow in-situ measurements of the open-sky energy spectrum of atmospheric muons, that is needed to asses a reference model of the through-target integrated flux. Here we describe our plans for the production of a Cherenkov telescope with suitable characteristics for installation in the summit zone of Etna volcano. <P /
Software design of the ASTRI camera server proposed for the Cherenkov Telescope Array
The Italian National Institute for Astrophysics (INAF) is leading the ASTRI project within the ambitious Cherenkov Telescope Array (CTA), the next generation of ground-based observatories for very high energy gamma-ray astronomy. In the framework of the small sized telescopes (SST), a first goal of the ASTRI project is the realization of an end-to-end prototype in dual-mirror configuration (2M) with the camera composed of a matrix of Silicon photo-multiplier sensors managed by innovative front-end and back-end electronics. The prototype, named ASTRI SST-2M, is installed in Italy at the INAF "M.G. Fracastoro" observing station located at Serra La Nave, 1735 m a.s.l. on Mount Etna, Sicily. As a second step, the ASTRI project is focused on the implementation of a mini-array composed at least of nine ASTRI telescopes and proposed to be placed at the CTA southern site. This paper outlines the design of the camera server software that will be installed on the ASTRI mini-array. The software is based on the version installed on the ASTRI SST-2M prototype operating in a single telescope configuration. The migration from single telescope to mini-array context has required additional interfaces in order to guarantee high interoperability with other software and hardware components. In the mini-array configuration each camera communicates with its own camera server via a dedicated high rate data link. The primary goal of the camera server is to acquire the bulk data, packet by packet, without any data loss and to timestamp each packet very precisely. During array operation, the camera server receives from the SoftWare Array Trigger (SWAT) the list of science events that participate in stereo triggered events. These science events, and all others that are flagged either by the camera as interleaved calibration or by the camera server as possible single-muon events, are sent to the Array DAQ. All remaining science events will be discarded. A suitable buffer is provided to perform this processing on all the incoming event packets. The camera server provides interfaces to the array control software to allow for monitoring and control during array operations. In this paper we present the design of the camera server software with particular emphasis on the external interfaces. In addition, we report the results of the first integration activities and performance tests. <P /
Apparatus and method for non-invasive inspection of solid bodies by muon imaging
The present invention has application in the technical field of measuring instruments and it relates to an apparatus for non-invasive inspection of solid bodies by muon imaging usable in civil engineering, archeology, volcanology, tectonics and everywhere a radiographic and/or tomographic non-destructive inspection of geological and/or engineering structures, even of large dimensions, is necessary The invention further relates to a method for non-invasive inspection by muon imaging implementable by said apparatus