E. Mach

Prototype of the SST-1M Telescope Structure for the Cherenkov Telescope Array

A single-mirror small-size (SST-1M) Davies-Cotton telescope with a dish diameter of 4 m has been built by a consortium of Polish and Swiss institutions as a prototype for one of the proposed small-size telescopes for the southern observatory of the Cherenkov Telescope Array (CTA). The design represents a very simple, reliable, and cheap solution. The mechanical structure prototype with its drive system is now being tested at the Institute of Nuclear Physics PAS in Krakow. Here we present the design of the prototype and results of the performance tests of the structure and the drive and control system.

Using muon rings for the optical throughput calibration of the SST-1M prototype for the Cherenkov Telescope Array

S. Toscano∗ a,n, E. Prandinia E-mail: simona.toscano@vub.ac.be W. Bilnikk, J. Blockic, L. .Bogaczm, T .Bulikd , F. Cadouxb, A. Christovb, M. Curyloc, D. della Volpeb, M. Dyrdac, Y. Favreb, A. Frankowskig, Ł. Grudnikic, M. Grudzinskad , M. Hellerb, B. Idźkowskie, M. Jamrozye, M. Janiakg, J. Kasperekk, K. Lalikk, E. Lyarda, E. Machc, D. Mandatl , A. Marszalekc,e, J. Michalowskic, R. Moderskig, T. Montarulib, A. Neronova, J. Niemiecc, M. Ostrowskie, P. Paśko f , M. Pechl , A. Porcellib, P. Rajdak, M. Rameezb, E. Jr. Schioppab, P. Schovanekl , K. Seweryn f , K. Skowronc, V. Sliusar j, M. Sowinskic, Ł. Stawarze, M. Stodulskae, M. Stodulskic, I. Troyano Pujadasb, R. Waltera, M. Wiȩcekk, A. Zagdanskie, K. Ziȩtarae, P. Żychowskic for the CTA Consortium† a. ISDC, Observatoire de Geneve, Universite de Geneve, 1290 Versoix, Switzerland. b. Department de physique nucleaire et corpusculaire, Universite de Geneve, CH-1205 Switzerland. c. Instytut Fizyki Jadrowej im. H. Niewodniczanskiego Polskiej Akademii Nauk, 31-342 Krakow, Poland. d. Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warsaw, Poland e. Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244, Krakow, Poland. f. Centrum Badan Kosmicznych Polskiej Akademii Nauk, 18a Bartycka str., 00-716 Warsaw, Poland. g. Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warsaw, Poland. j. Astronomical Observatory, Taras Shevchenko Nat. University of Kyiv, Observatorna str., 3, Kyiv, Ukraine. k. AGH University of Science and Technology, al.Mickiewicza 30, Krakow, Poland, l. Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic. m. Department of Information Technologies, Jagiellonian University, 30-348 Krakow, Poland. n. Vrije Universiteit Brussels, Pleinlaan 2 1050 Brussels, Belgium.

Development of an optical system for the SST-1M telescope of the Cherenkov Telescope Array observatory

The prototype of a Davies-Cotton small size telescope (SST-1M) has been designed and developed by a consortium of Polish and Swiss institutions and proposed for the Cherenkov Telescope Array (CTA) observatory. The main purpose of the optical system is to focus the Cherenkov light emitted by extensive air showers in the atmosphere onto the focal plane detectors. The main component of the system is a dish consisting of 18 hexagonal mirrors with a total effective collection area of 6.47 m 2 (including the shadowing and estimated mirror reflectivity). Such a solution was chosen taking into account the analysis of the Cherenkov light propagation and based on optical simulations. The proper curvature and stability of the dish is ensured by the mirror alignment system and the isostatic interface to the telescope structure. Here we present the design of the optical subsystem together with the performance measurements of its components.

The single mirror small size telescope (SST-1M) of the Cherenkov Telescope Array

The Small Size Telescope with Single Mirror (SST-1M) is one of the proposed types of Small Size Telescopes (SST) for the Cherenkov Telescope Array (CTA). The CTA south array will be composed of about 100 telescopes, out of which about 70 are of SST class, which are optimized for the detection of gamma rays in the energy range from 5 TeV to 300 TeV. The SST-1M implements a Davies-Cotton optics with a 4 m dish diameter with a field of view of 9°. The Cherenkov light produced in atmospheric showers is focused onto a 88 cm wide hexagonal photo-detection plane, composed of 1296 custom designed large area hexagonal silicon photomultipliers (SiPM) and a fully digital readout and trigger system. The SST-1M camera has been designed to provide high performance in a robust as well as compact and lightweight design. In this contribution, we review the different steps that led to the realization of the telescope prototype and its innovative camera.

The single mirror small sized telescope for the Cherenkov telescope array

The Small Size Telescope with Single Mirror (SST-1M) is one of the proposed types of Small Size Telescopes (SST) for the Cherenkov Telescope Array (CTA). About 70 SST telescopes will be part the CTA southern array which will also include Medium Sized Telescopes (MST) in its threshold configuration. Optimized for the detection of gamma rays in the energy range from 5 TeV to 300 TeV, the SST-1M uses a Davies-Cotton optics with a 4 m dish diameter with a field of view of 9 degrees. The Cherenkov light resulting from the interaction of the gamma-rays in the atmosphere is focused onto a 88 cm side-to-side hexagonal photo-detection plane. The latter is composed of 1296 hollow light guides coupled to large area hexagonal silicon photomultipliers (SiPM). The SiPM readout is fully digital readout as for the trigger system. The compact and lightweight design of the SST-1M camera offers very high performance ideal for gamma-ray observation requirement. In this contribution, the concept, design, performance and status of the first telescope prototype are presented.

Performance of a small size telescope (SST-1M) camera for gamma-ray astronomy with the Cherenkov Telescope Array

The foreseen implementations of the Small Size Telescopes (SST) in CTA will provide unique insights into the highest energy gamma rays offering fundamental means to discover and under- stand the sources populating the Galaxy and our local neighborhood. Aiming at such a goal, the SST-1M is one of the three different implementations that are being prototyped and tested for CTA. SST-1M is a Davies-Cotton single mirror telescope equipped with a unique camera technology based on SiPMs with demonstrated advantages over classical photomultipliers in terms of duty-cycle. In this contribution, we describe the telescope components, the camera, and the trigger and readout system. The results of the commissioning of the camera using a dedicated test setup are then presented. The performances of the camera first prototype in terms of expected trigger rates and trigger efficiencies for different night-sky background conditions are presented, and the camera response is compared to end-to-end simulations.

Control Software for the SST-1M Small-Size Telescope prototype for the Cherenkov Telescope Array

The SST-1M is a 4-m Davies-Cotton atmospheric Cherenkov telescope optimized to provide gamma-ray sensitivity above a few TeV. The SST-1M is proposed as part of the Small-Size Telescope array for the Cherenkov Telescope Array (CTA), the first prototype has already been deployed. The SST-1M control software of all subsystems (active mirror control, drive system, safety system, photo-detection plane, DigiCam, CCD cameras) and the whole telescope itself (master controller) uses the standard software design proposed for all CTA telescopes based on the ALMA Common Software (ACS) developed to control the Atacama Large Millimeter Array (ALMA). Each subsystem is represented by a separate ACS component, which handles the communication to and the operation of the subsystem. Interfacing with the actual hardware is performed via the OPC UA communication protocol, supported either natively by dedicated industrial standard servers (PLCs) or separate service applications developed to wrap lower level protocols (e.g. CAN bus, camera slow control) into OPC UA. Early operations of the telescope without the camera were already carried out. The camera is fully assembled and is capable to perform data acquisition using artificial light source.

Development of a strategy for calibrating the novel SiPM camera of the SST-1M telescope proposed for the Cherenkov Telescope Array

CTA will comprise a sub-array of up to 70 small size telescopes (SSTs) at the southern array. The SST-1M project, a 4 m-diameter Davies Cotton telescope with 9 degrees FoV and a 1296 pixels SiPM camera, is designed to meet the requirements of the next generation ground based gammaray observatory CTA in the energy range above 3 TeV. Silicon photomultipliers (SiPM) cameras of gamma-ray telescopes can achieve good performance even during high night sky background conditions. Defining a fully automated calibration strategy of SiPM cameras is of great importance for large scale production validation and online calibration. The SST-1M sub-consortium developed a software compatible with CTA pipeline software (CTApipe). The calibration of the SST-1M camera is based on the Camera Test Setup (CTS), a set of LED boards mounted in front of the camera. The CTS LEDs are operated in pulsed or continuous mode to emulate signal and night sky background respectively. Continuous and pulsed light data analysis allows us to extract single pixel calibration parameters to be used during CTA operation.

First light on a new fully digital camera based on SiPM for CTA SST-1M telescope

The Cherenkov Telescope Array (CTA) will explore with unprecedented precision the Universe in the gammaray domain covering an energy range from 50 GeV to more the 300 TeV. To cover such a broad range with a sensitivity which will be ten time better than actual instruments, different types of telescopes are needed: the Large Size Telescopes (LSTs), with a ∼24 m diameter mirror, a Medium Size Telescopes (MSTs), with a ∼12 m mirror and the small size telescopes (SSTs), with a ∼4 m diameter mirror. The single mirror small size telescope (SST-1M), one of the proposed solutions to become part of the small-size telescopes of CTA, will be equipped with an innovative camera. The SST-1M has a Davies-Cotton optical design with a mirror dish of 4 m diameter and focal ratio 1.4 focussing the Cherenkov light produced in atmospheric showers onto a 90 cm wide hexagonal camera providing a FoV of 9 degrees. The camera is an innovative design based on silicon photomultipliers (SiPM ) and adopting a fully digital trigger and readout architecture. The camera features 1296 custom designed large area hexagonal SiPM coupled to hollow optical concentrators to achieve a pixel size of almost 2.4 cm. The SiPM is a custom design developed with Hamamatsu and with its active area of almost 1 cm2 is one of the largest monolithic SiPM existing. Also the optical concentrators are innovative being light funnels made of a polycarbonate substrate coated with a custom designed UV-enhancing coating. The analog signals coming from the SiPM are fed into the fully digital readout electronics, where digital data are processed by high-speed FPGAs both for trigger and readout. The trigger logic, implemented into an Virtex 7 FPGA, uses the digital data to elaborate a trigger decision by matching data against predefined patterns. This approach is extremely flexible and allows improvements and continued evolutions of the system. The prototype camera is being tested in laboratory prior to its installation expected in fall 2017 on the telescope prototype in Krakow (Poland). In this contribution, we will describe the design of the camera and show the performance measured in laboratory.

Performance of the SST-1M telescope of the Cherenkov Telescope Array observatory

R. Moderskic,W. Bilnikk, J. Blockig, L. Bogacze, T. Bulikd , F. Cadouxa, A. Christova, M. Chruślinskad , M. Curylog, D. della Volpea, M. Dyrdag, Y. Favrea, A. Frankowskic, Ł. Grudnikg, M. Grudzinskad , M. Hellera, B. Idźkowskib, M. Jamrozyb, M. Janiakc, J. Kasperekk, K. Lalikk, E. Lyard f , E. Machg, D. Mandatm, A. Marszalekh,b, J. Michalowskig, T. Montarulia, A. Neronov f , J. Niemiecg, M. Ostrowskib, P. Paśkoh, M. Pechm, A. Porcelli∗a, E. Prandini f , E. Puescheln, P. Rajdak, M. Rameeza, P. Rozwadowskid , E. jr Schioppaa, P. Schovanekm, K. Sewerynh, K. Skowrong, V. Sliusari, M. Sowinskig, Ł. Stawarzb, M. Stodulskab, M. Stodulskig, S. Toscano f ,l, I. Troyano Pujadasa, R. Walter f , M. Wiȩcekk, A. Zagdanskib, K. Ziȩtarab, P. Żychowskig for the CTA Consortium† aDPNC – Universite de Geneve, Geneve, Switzerland bAstronomical Observatory, Jagiellonian University, Krakow, Poland cNicolaus Copernicus Astronomical Centre, Polish Academy of Sciences, Warsaw, Poland dAstronomical Observatory, University of Warsaw, Warsaw,Poland eDepartment of Information Technologies, Jagiellonian University, Krakow, Poland f ISDC, Observatoire de Geneve, Universite de Geneve, Versoix, Switzerland gInstytut Fizyki Jadrowej im. H. Niewodniczanskiego Polskiej Akademii Nauk, Krakow, Poland hCentrum Badan Kosmicznych Polskiej Akademii Nauk, Warsaw, Poland iAstronomical Observatory, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine kAGH University of Science and Technology, Krakow, Poland lVrije Universiteit Brussels, Brussels, Belgium mInstitute of Physics of the Czech Academy of Sciences, Prague, Czech Republic nUniversity College Dublin, Ireland