KEYWORDS: Software development, Telescopes, Data modeling, Computer architecture, Control systems, Atmospheric Cherenkov telescopes, Data acquisition, Data archive systems, Design, Cameras
The Astrophysics with Italian Replicating Technology Mirrors (ASTRI) Mini-Array is an international collaboration led by the Italian National Institute for Astrophysics (INAF) and devoted to imaging atmospheric Cherenkov light for very-high γ-ray astrophysics, detection of cosmic-rays, and stellar Hambury-Brown intensity interferometry. The project is deploying an array of nine dual-mirror aplanatic imaging atmospheric Cherenkov telescopes of 4-m class at the Teide Observatory on Tenerife in the Canary Islands. Based on SiPM sensors, the focal plane camera covers an unprecedented field of view of 10.5 deg in diameter. The array is most sensitive to γ-ray radiation above 1 up to 200 TeV, with an angular resolution of 3 arcmin, better than the current particle arrays, such as LHAASO and HAWC. We describe the overall software architecture of the ASTRI Mini-Array and the software engineering approach for its development. The software covers the entire life cycle of the Mini-Array, from scheduling to remote operations, data acquisition, and processing until data dissemination. The on-site control software allows remote array operations from different locations, including automated reactions to critical conditions. All data are collected every night, and the array trigger is managed post facto. The high-speed networking connection between the observatory site and the Data Center in Rome allows for ready data availability for stereoscopic event reconstruction, data processing, and almost real-time science products generation.
The ASTRI ("Astrofisica con Specchi a Tecnologia Replicante Italiana") program is a collaborative international effort led by the Italian National Institute for Astrophysics (INAF) for developing and operating an array of nine 4-m class Imaging Atmospheric Cherenkov Telescopes (IACTs), sensitive to gamma-ray radiation at energies above 1 TeV, under deployment at the Teide Observatory in Tenerife, in the Canary Islands. In order to support the development, installation and operations of the ASTRI Mini-Array an on-site Information and Communication Technology (ICT) Infrastructure has been designed. In this paper we describe the main objective of the ICT infrastructure project and its configuration in the initial phase. This ICT infrastructure, which we called mini-ICT (m-ICT), include all hardware and services needed to support the installation and testing of the first three Telescopes Mechanical Structures of the ASTRI Mini-Array that will be installed at the Teide site by 2022, before the definitive ICT infrastructure will be up and running. The m-ICT includes a virtualization system (ProxMox) and a container system to run the ASTRI Mini-Array on-site control and monitoring software. It also includes all interconnection functions of his Local Area Network (LAN) and the necessary network services: Network Time Protocol (NTP), Domain name Server (DNS), Network Address translator (NAT), Virtual Private Network (VPN), Routing. Internet connection will also be supported so that the connection with the ASTRI Data Centre in Italy (Rome) can be tested and all test results transferred to this persistent storage.
The ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) Project was born as a collaborative international effort led by the Italian National Institute for Astrophysics (INAF) to design and realize an end-to-end prototype of the Small-Sized Telescope (SST) of the Cherenkov Telescope Array (CTA) in a dual-mirror configuration (2M). The prototype, named ASTRI-Horn, has been operational since 2014 at the INAF observing station located on Mt. Etna (Italy). The ASTRI Project is now building the ASTRI Mini-Array consisting of nine ASTRI-Horn-like telescopes to be installed and operated at the Teide Observatory (Spain). The ASTRI software is aimed at supporting the Assembly Integration and Verification (AIV), and the operations of the ASTRI Mini-Array. The Array Data Acquisition System (ADAS) includes all hardware, software and communication infrastructure required to gather the bulk data of the Cherenkov Cameras and the Intensity Interferometers installed on the telescopes, and make these data available to the Online Observation Quality System (OOQS) for the on-site quick look, and to the Data Processing System (DPS) for the off-site scientific pipeline. This contribution presents the ADAS software architecture according to the use cases and requirement specifications, with particular emphasis on the interfaces with the Back End Electronics (BEE) of the instruments, the array central control, the OOQS, and the DPS.
The ASTRI Mini-Array is an international project led by INAF to construct and operate nine Imaging Atmospheric Cherenkov Telescopes with the scientific goals of studying several classes of objects possibly emitting at energies higher than some TeVs and of performing stellar intensity interferometry observations. The telescopes array will be installed at the Teide Observatory (Tenerife, Spain). A Supervisory Control And Data Acquisition (SCADA) software system will be developed to manage the ASTRI Mini-Array allowing its control remotely, from several locations. One of the most important components of the SCADA system is the Telescope Control System (TCS), i.e. the system responsible for the control and supervision of each telescope. The TCS includes several supervisor components, that interface with the telescope local control systems, the hardware and software that control the telescopes hardware devices such as the telescope mount drive systems and the Cherenkov camera, via the Open Platform Communications - Unified Architecture (OPC-UA) standard. These supervisors are then controlled by a telescope manager component responsible for the execution of the single telescope scientific and technical operations requested, orchestrated and synchronized centrally by the SCADA array central controller. This contribution describes the TCS architecture, design and development approach in the context of the general SCADA architecture and of the ALMA Common Software, the framework chosen for the development of all SCADA software of the ASTRI Mini-Array.
KEYWORDS: Data modeling, Atmospheric Cherenkov telescopes, Control systems, Software development, Telescopes, Data processing, Data archive systems, Data acquisition, Calibration, Computer architecture
The ASTRI Mini-Array is an international collaboration led by the Italian National Institute for Astrophysics (INAF) and devoted to the imaging of atmospheric Cherenkov light for very-high gamma-ray astronomy. The project is deploying an array of 9 telescopes sensitive above 1 TeV. In this contribution, we present the architecture of the software that covers the entire life cycle of the observatory, from scheduling to remote operations and data dissemination. The high-speed networking connection available between the observatory site, at the Canary Islands, and the Data Center in Rome allows for ready data availability for stereo triggering and data processing.
The ASTRI project was born as a collaborative international effort led by the Italian National Institute for Astrophysics (INAF) to design and realise an end-to-end prototype of the Small-Sized Telescope (SST) of the Cherenkov Telescope Array (CTA) in a dual-mirror configuration (2M). The ASTRI Mini-Array is being installed at the Teide Observatory on the island of Tenerife (Canary Islands) and represents the first system of atmospheric Cherenkov telescopes completely dedicated to the study of very high energy gamma emission. The ASTRI software supports the operations of the ASTRI Mini-Array. The Array Data Acquisition System (ADAS) includes all hardware, software and communication infrastructure required to acquire, buffer and store the bulk data of the ASTRI Mini-Array instruments which will be installed to the ASTRI telescopes. The Cherenkov Camera Data Acquisition, one for each telescope, is a component of the ADAS. It connects with the Back End electronics (BEE) of the Cherenkov cameras to acquire and save the raw data. The Cherenkov Camera Dispatcher gets data from the Camera Data Acquisition and interfaces with the Online Observation Quality System (OOQS) to decode and send acquired data in near real-time. The OOQS aims to perform the data quality analysis during the observations. According to the requirement specifications, we are redesigning the software to decode and send the raw data to the OOQS at a rate of 1 kHz. This contribution presents the assessment of a solution based on Avro software for data serialisation and a Kafka server for the data transmission to the OOQS.
KEYWORDS: Telescopes, Atmospheric Cherenkov telescopes, Data modeling, Databases, Data acquisition, Information technology, Gamma radiation, Data archive systems, Control systems, Computer architecture
The ASTRI Mini-Array is a project for the Cherenkov astronomy in the TeV energy range. ASTRI Mini- Array consists of nine Imaging Atmospheric Cherenkov telescopes located at the Teide Observatory (Canarias Islands). Large volumes of monitoring and logging data result from the operation of a large-scale astrophysical observatory. In the last few years, several “Big Data” technologies have been developed to deal with such volumes of data, especially in the Internet of Things (IoT) framework. We present the Monitoring, Logging, and Alarm (MLA) system for the ASTRI Mini-Array aimed at supporting the analysis of scientific data and improving the operational activities of the telescope facility. The MLA system was designed and built considering the latest software tools and concepts coming from Big Data and IoT to respond to the challenges posed by the operation of the array. A particular relevance has been given to satisfying the reliability, availability, and maintainability requirements towards all the array sub-systems and auxiliary devices. The system architecture has been designed to scale up with the number of devices to be monitored and with the number of software components to be considered in the distributed logging system.
Large volumes of monitoring and logging data result from the operation of a large scale astrophysical observatory. In the last few years several “Big Data” technologies have been developed to deal with such volumes of data especially in the Internet of Things (IoT) framework. We present the logging, monitoring and alarm system architecture for the ASTRI Mini-Array aimed at supporting the analysis of scientific data and improving the operational activities of the telescope facility . A prototype was designed and built considering the latest software tools and concepts coming from Big Data and IoT and a particular relevance has been given in satisfying quality requirements such as performance, scalability and availability.
QUBIC (a Q and U Bolometric Interferometer for Cosmology) is a next generation cosmology experiment designed to detect the B-mode polarisation of the Cosmic Microwave Background (CMB). A B-mode detection is hard evidence of Inflation in the ΛCDM model. QUBIC aims to accomplish this by combining novel technologies to achieve the sensitivity required to detect the faint B-mode signal. QUBIC uses technologies such as a rotating half-wave plate, cryogenics, interferometric horns with self-calibration switches and transition edge sensor bolometers. A Technical Demonstrator (TD) is currently being calibrated in APC in Paris before observations in Argentina in 2021. As part of the calibration campaign, the spectral response of the TD is measured to test and validate QUBIC's spectro-imaging capability. This poster gives an overview of the methods used to measure the spectral response and a comparison of the instrument data with theoretical predictions and optical simulations.
The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10-16W= p √Hz
QUBIC, the QU Bolometric Interferometer for Cosmology, is a novel forthcoming instrument to measure the B-mode polarization anisotropy of the Cosmic Microwave Background. The detection of the B-mode signal will be extremely challenging; QUBIC has been designed to address this with a novel approach, namely bolometric interferometry. The receiver cryostat is exceptionally large and cools complex optical and detector stages to 40 K, 4 K, 1 K and 350 mK using two pulse tube coolers, a novel 4He sorption cooler and a double-stage 3He/4He sorption cooler. We discuss the thermal and mechanical design of the cryostat, modelling and thermal analysis, and laboratory cryogenic testing.
We present a preliminary study of the sky scanning strategy for the LSPE-STRIP instrument, a ground-based telescope that will be installed at the Teide Observatory (Tenerife, Canary Islands) in early 2019 and will observe the polarized emission of about 25% of the sky in the Northern Hemisphere at 43 and 95 GHz. The same sky portion will be observed at 140, 220 and 240 GHz by LSPE-SWIPE, a stratospheric balloon scheduled for a long-duration flight around the North Pole during the Arctic winter of 2019/2020. The combination of data from the two instruments aims at constraining the tensor-to-scalar ratio down to r ~ 0.03. In our paper we discuss the main scanning strategy requirements (overlap with SWIPE coverage, sensitivity distribution, observation of calibration sources) and show how we obtain a trade-off by spinning the telescope around the azimuth axis with constant elevation and angular velocity. The combination of the telescope motion with the Earth rotation will guarantee the access to the large angular scales. We will observe periodically the Crab Nebula as well as the Perseus molecular cloud. The Crab is one of the best known polarized sources in the sky and it will be observed for calibration purposes. The second one is a source of Anomalous Microwave Emission that could be characterized both in intensity and polarization.
QUBIC, the Q & U Bolometric Interferometer for Cosmology, is a novel ground-based instrument that aims to measure the extremely faint B-mode polarisation anisotropy of the cosmic microwave background at intermediate angular scales (multipoles of 𝑙 = 30 − 200). Primordial B-modes are a key prediction of Inflation as they can only be produced by gravitational waves in the very early universe. To achieve this goal, QUBIC will use bolometric interferometry, a technique that combines the sensitivity of an imager with the immunity to systematic effects of an interferometer. It will directly observe the sky through an array of back-to-back entry horns whose beams will be superimposed using a cooled quasioptical beam combiner. Images of the resulting interference fringes will be formed on two focal planes, each tiled with transition-edge sensors, cooled down to 320 mK. A dichroic filter placed between the optical combiner and the focal planes will select two frequency bands (centred at 150 GHz and 220 GHz), one frequency per focal plane. Polarization modulation will be achieved using a cold stepped half-wave plate (HWP) and polariser in front of the sky-facing horns.
The full QUBIC instrument is described elsewhere1,2,3,4; in this paper we will concentrate in particular on simulations of the optical combiner (an off-axis Gregorian imager) and the feedhorn array. We model the optical performance of both the QUBIC full module and a scaled-down technological demonstrator which will be used to validate the full instrument design. Optical modelling is carried out using full vector physical optics with a combination of commercial and in-house software. In the high-frequency channel we must be careful to consider the higher-order modes that can be transmitted by the horn array. The instrument window function is used as a measure of performance and we investigate the effect of, for example, alignment and manufacturing tolerances, truncation by optical components and off-axis aberrations. We also report on laboratory tests carried on the QUBIC technological demonstrator in advance of deployment to the observing site in Argentina.
QUBIC, the Q & U Bolometric Interferometer for Cosmology, is a novel ground-based instrument that has been designed to measure the extremely faint B-mode polarisation anisotropy of the cosmic microwave background at intermediate angular scales (multipoles of 𝑙 = 30 − 200). Primordial B-modes are a key prediction of Inflation as they can only be produced by gravitational waves in the very early universe. To achieve this goal, QUBIC will use bolometric interferometry, a technique that combines the sensitivity of an imager with the systematic error control of an interferometer. It will directly observe the sky through an array of 400 back-to-back entry horns whose signals will be superimposed using a quasi-optical beam combiner. The resulting interference fringes will be imaged at 150 and 220 GHz on two focal planes, each tiled with NbSi Transition Edge Sensors, cooled to 320 mK and read out with time-domain multiplexing. A dichroic filter placed between the optical combiner and the focal planes will select the two frequency bands. A very large receiver cryostat will cool the optical and detector stages to 40 K, 4 K, 1 K and 320 mK using two pulse tube coolers, a novel 4He sorption cooler and a double-stage 3He/4He sorption cooler. Polarisation modulation and selection will be achieved using a cold stepped half-wave plate (HWP) and polariser, respectively, in front of the sky-facing horns. A key feature of QUBIC’s ability to control systematic effects is its ‘self-calibration’ mode where fringe patterns from individual equivalent baselines can be compared. When observing, however, all the horns will be open simultaneously and we will recover a synthetic image of the sky in the I, Q and U Stokes’ parameters. The synthesised beam pattern has a central peak of approximately 0.5 degrees in width, with secondary peaks further out that are damped by the 13-degree primary beam of the horns. This is Module 1 of QUBIC which will be installed in Argentina, near the city of San Antonio de los Cobres, at the Alto Chorrillos site (4869 m a.s.l.), Salta Province. Simulations have shown that this first module could constrain the tensor-to-scalar ratio down to σ(r) = 0.01 after a two-year survey. We aim to add further modules in the future to increase the angular sensitivity and resolution of the instrument. The QUBIC project is proceeding through a sequence of steps. After an initial successful characterisation of the detection chain, a technological demonstrator is being assembled to validate the full instrument design and to test it electrically, thermally and optically.
The technical demonstrator is a scaled-down version of Module 1 in terms of the number of detectors, input horns and pulse tubes and a reduction in the diameter of the combiner mirrors and filters, but is otherwise similar. The demonstrator will be upgraded to the full module in 2019. In this paper we give an overview of the QUBIC project and instrument.
QUBIC (the Q and U Bolometric Interferometer for Cosmology) is a ground-based experiment which seeks to improve the current constraints on the amplitude of primordial gravitational waves. It exploits the unique technique, among Cosmic Microwave Background experiments, of bolometric interferometry, combining together the sensitivity of bolometric detectors with the control of systematic effects typical of interferometers. QUBIC will perform sky observations in polarization, in two frequency bands centered at 150 and 220 GHz, with two kilo-pixel focal plane arrays of NbSi Transition-Edge Sensors (TES) cooled down to 350 mK. A subset of the QUBIC instrument, the so called QUBIC Technological Demonstrator (TD), with a reduced number of detectors with respect to the full instrument, will be deployed and commissioned before the end of 2018.
The voltage-biased TES are read out with Time Domain Multiplexing and an unprecedented multiplexing (MUX) factor equal to 128. This MUX factor is reached with two-stage multiplexing: a traditional one exploiting Superconducting QUantum Interference Devices (SQUIDs) at 1K and a novel SiGe Application-Specific Integrated Circuit (ASIC) at 60 K. The former provides a MUX factor of 32, while the latter provides a further 4. Each TES array is composed of 256 detectors and read out with four modules of 32 SQUIDs and two ASICs. A custom software synchronizes and manages the readout and detector operation, while the TES are sampled at 780 Hz (100kHz/128 MUX rate).
In this work we present the experimental characterization of the QUBIC TES arrays and their multiplexing readout chain, including time constant, critical temperature, and noise properties.
In this paper we discuss the latest developments of the STRIP instrument of the “Large Scale Polarization Explorer” (LSPE) experiment. LSPE is a novel project that combines ground-based (STRIP) and balloon-borne (SWIPE) polarization measurements of the microwave sky on large angular scales to attempt a detection of the “B-modes” of the Cosmic Microwave Background polarization. STRIP will observe approximately 25% of the Northern sky from the “Observatorio del Teide” in Tenerife, using an array of forty-nine coherent polarimeters at 43 GHz, coupled to a 1.5 m fully rotating crossed-Dragone telescope. A second frequency channel with six-elements at 95 GHz will be exploited as an atmospheric monitor. At present, most of the hardware of the STRIP instrument has been developed and tested at sub-system level. System-level characterization, starting in July 2018, will lead STRIP to be shipped and installed at the observation site within the end of the year. The on-site verification and calibration of the whole instrument will prepare STRIP for a 2-years campaign for the observation of the CMB polarization.
Remnant radiation from the early universe, known as the Cosmic Microwave Background (CMB), has been redshifted and cooled, and today has a blackbody spectrum peaking at millimetre wavelengths. The QUBIC (Q&U Bolometric Interferometer for Cosmology) instrument is designed to map the very faint polaristion structure in the CMB. QUBIC is based on the novel concept of bolometric interferometry in conjunction with synthetic imaging. It will have a large array of input feedhorns, which creates a large number of interferometric baselines.
The beam from each feedhorn is passed through an optical combiner, with an off-axis compensated Gregorian design, to allow the generation of the synthetic image. The optical-combiner will operate in two frequency bands (150 and 220 GHz with 25% and 18.2 % bandwidth respectively) while cryogenically cooled TES bolometers provide the sensitivity required at the image plane.
The QUBIC Technical Demonstrator (TD), a proof of technology instrument that contains 64 input feed-horns, is currently being built and will be installed in the Alto Chorrillos region of Argentina. The plan is then for the full QUBIC instrument (400 feed-horns) to be deployed in Argentina and obtain cosmologically significant results.
In this paper we will examine the output of the manufactered feed-horns in comparison to the nominal design. We will show the results of optical modelling that has been performed in anticipation of alignment and calibration of the TD in Paris, in particular testing the validity of real laboratory environments. We show the output of large calibrator sources (50 ° full width haf max Gaussian beams) and the importance of accurate mirror definitions when modelling large beams. Finally we describe the tolerance on errors of the position and orientation of mirrors in the optical combiner.
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