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Pointing Calibration for the Cherenkov Telescope Array Medium Size Telescope Prototype  [PDF]
Louise Oakes,Bagmeet Behera,Juergen Baehr,Sandra Gruenewald,Tobias Raeck,Stefan Schlenstedt,Anja Schubert,Ullrich Schwanke,for the CTA Consortium
Physics , 2013,
Abstract: Pointing calibration is an offline correction applied in order to obtain the true pointing direction of a telescope. The Cherenkov Telescope Array (CTA) aims to have the precision to determine the position of point-like as well as slightly extended sources, with the goal of systematic errors less than 7 arc seconds in space angle. This poster describes the pointing calibration concept being developed for the CTA Medium Size Telescope (MST) prototype at Berlin-Adlershof, showing test results and preliminary measurements. The MST pointing calibration method uses two CCD cameras, mounted on the telescope dish, to determine the true pointing of the telescope. The "Lid CCD" is aligned to the optical axis of the telescope, calibrated with LEDs on the dummy gamma-camera lid; the "Sky CCD" is pre-aligned to the Lid CCD and the transformation between the Sky and Lid CCD camera fields of view is precisely modelled with images from special pointing runs which are also used to determine the pointing model. During source tracking, the CCD cameras record images which are analysed offline using software tools including Astrometry.net to determine the true pointing coordinates.
Construction of a Medium-Sized Schwarzschild-Couder Telescope for the Cherenkov Telescope Array: Implementation of the Cherenkov-Camera Data Acquisition System  [PDF]
M. Santander,J. Buckley,B. Humensky,R. Mukherjee,for the CTA Consortium
Physics , 2015,
Abstract: A medium-sized Schwarzchild-Couder Telescope (SCT) is being developed as a possible extension for the Cherenkov Telescope Array (CTA). The Cherenkov camera of the telescope is designed to have 11328 silicon photomultiplier pixels capable of capturing high-resolution images of air showers in the atmosphere. The combination of the large number of pixels and the high trigger rate (> 5 kHz) expected for this telescope results in a multi-Gbps data throughput. This sets challenging requirements on the design and performance of a data acquisition system for processing and storing this data. A prototype SCT (pSCT) with a partial camera containing 1600 pixels, covering a field of view of 2.5 x 2.5 square degrees, is being assembled at the F.L. Whipple Observatory. We present the design and current status of the SCT data acquisition system.
Construction of a medium-sized Schwarzschild-Couder telescope as a candidate for the Cherenkov Telescope Array: development of the optical alignment system  [PDF]
D. Nieto,S. Griffiths,B. Humensky,P. Kaaret,M. Limon,I. Mognet,A. Peck,A. Petrashyk,D. Ribeiro,J. Rousselle,B. Stevenson,V. Vassiliev,P. Yu,for the CTA Consortium
Physics , 2015,
Abstract: The Cherenkov Telescope Array (CTA) is an international project for a next-generation ground-based gamma-ray observatory. CTA, conceived as an array of tens of imaging atmospheric Cherenkov telescopes, comprising small, medium and large-size telescopes, is aiming to improve on the sensitivity of current-generation experiments by an order of magnitude and provide energy coverage from 20 GeV to more than 300 TeV. The Schwarzschild-Couder (SC) medium-size candidate telescope model features a novel aplanatic two-mirror optical design capable of a wide field-of-view with significantly improved imaging resolution as compared to the traditional Davis-Cotton optics design. Achieving this imaging resolution imposes strict alignment requirements to be accomplished by a dedicated alignment system. In this contribution we present the status of the development of the SC optical alignment system, soon to be materialized in a full-scale prototype SC medium-size telescope at the Fred Lawrence Whipple Observatory in southern Arizona.
Recent developments for the testing of Cherenkov Telescope Array mirrors and actuators in Tübingen  [PDF]
J. Dick,A. Bonardi,S. Bressel,M. Capasso,S. Diebold,F. Eisenkolb,D. Gottschall,E. Kendziorra,G. Pühlhofer,S. Renner,A. Santangelo,T. Schanz,C. Tenzer
Physics , 2015,
Abstract: The Cherenkov Telescope Array (CTA) is the next generation Cherenkov telescope facility. It will consist of a large number of segmented-mirror telescopes of three different diameters, placed in two locations, one in the northern and one in the southern hemisphere, thus covering the whole sky. The total number of mirror tiles will be on the order of 10,000, corresponding to a reflective area of ~10^4 m^2. The Institute for Astronomy and Astrophysics in T\"ubingen (IAAT) is currently developing mirror control alignment mechanics, electronics, and software optimized for the medium sized telescopes. In addition, IAAT is participating in the CTA mirror prototype testing. In this paper we present the status of the current developments, the main results of recent tests, and plans for the production phase of the mirror control system. We also briefly present the T\"ubingen facility for mirror testing.
Development of the Photomultiplier-Tube Readout System for the CTA Large Size Telescope  [PDF]
H. Kubo,R. Paoletti,Y. Awane,A. Bamba,M. Barcelo,J. A. Barrio,O. Blanch,J. Boix,C. Delgado,D. Fink,D. Gascon,S. Gunji,R. Hagiwara,Y. Hanabata,K. Hatanaka,M. Hayashida,M. Ikeno,S. Kabuki,H. Katagiri,J. Kataoka,Y. Konno,S. Koyama,T. Kishimoto,J. Kushida,G. Martinez,S. Masuda,J. M. Miranda,R. Mirzoyan,T. Mizuno,T. Nagayoshi,D. Nakajima,T. Nakamori,H. Ohoka,A. Okumura,R. Orito,T. Saito,A. Sanuy,H. Sasaki,M. Sawada,T. Schweizer,R. Sugawara,K. -H. Sulanke,H. Tajima,M. Tanaka,S. Tanaka,L. A. Tejedor,Y. Terada,M. Teshima,F. Tokanai,Y. Tsuchiya,T. Uchida,H. Ueno,K. Umehara,T. Yamamoto,for the CTA Consortium
Physics , 2013,
Abstract: We have developed a prototype of the photomultiplier tube (PMT) readout system for the Cherenkov Telescope Array (CTA) Large Size Telescope (LST). Two thousand PMTs along with their readout systems are arranged on the focal plane of each telescope, with one readout system per 7-PMT cluster. The Cherenkov light pulses generated by the air showers are detected by the PMTs and amplified in a compact, low noise and wide dynamic range gain block. The output of this block is then digitized at a sampling rate of the order of GHz using the Domino Ring Sampler DRS4, an analog memory ASIC developed at Paul Scherrer Institute. The sampler has 1,024 capacitors per channel and four channels are cascaded for increased depth. After a trigger is generated in the system, the charges stored in the capacitors are digitized by an external slow sampling ADC and then transmitted via Gigabit Ethernet. An onboard FPGA controls the DRS4, trigger threshold, and Ethernet transfer. In addition, the control and monitoring of the Cockcroft-Walton circuit that provides high voltage for the 7-PMT cluster are performed by the same FPGA. A prototype named Dragon has been developed that has successfully sampled PMT signals at a rate of 2 GHz, and generated single photoelectron spectra.
Development of a SiPM Camera for a Schwarzschild-Couder Cherenkov Telescope for the Cherenkov Telescope Array  [PDF]
A. N. Otte,J. Biteau,H. Dickinson,S. Funk,T. Jogler,C. A. Johnson,P. Karn,K. Meagher,H. Naoya,T. Nguyen,A. Okumura,M. Santander,L. Sapozhnikov,A. Stier,H. Tajima,L. Tibaldo,J. Vandenbroucke,S. Wakely,A. Weinstein,D. A. Williams,for the CTA Consortium
Physics , 2015,
Abstract: We present the development of a novel 11328 pixel silicon photomultiplier (SiPM) camera for use with a ground-based Cherenkov telescope with Schwarzschild-Couder optics as a possible medium-sized telescope for the Cherenkov Telescope Array (CTA). The finely pixelated camera samples air-shower images with more than twice the optical resolution of cameras that are used in current Cherenkov telescopes. Advantages of the higher resolution will be a better event reconstruction yielding improved background suppression and angular resolution of the reconstructed gamma-ray events, which is crucial in morphology studies of, for example, Galactic particle accelerators and the search for gamma-ray halos around extragalactic sources. Packing such a large number of pixels into an area of only half a square meter and having a fast readout directly attached to the back of the sensors is a challenging task. For the prototype camera development, SiPMs from Hamamatsu with through silicon via (TSV) technology are used. We give a status report of the camera design and highlight a number of technological advancements that made this development possible.
Status of the technologies for the production of the Cherenkov Telescope Array (CTA) mirrors  [PDF]
G. Pareschi,T. Armstrong,H. Baba,J. B?hr,A. Bonardi,G. Bonnoli,P. Brun,R. Canestrari,P. Chadwick,M. Chikawa,P. -H. Carton,V. de Souza,J. Dipold,M. Doro,D. Durand,M. Dyrda,A. F?rster,M. Garczarczyk,E. Giro,J. -F. Glicenstein,Y. Hanabata,M. Hayashida,M. Hrabovski,C. Jeanney,M. Kagaya,H. Katagiri,L. Lessio,D. Mandat,M. Mariotti,C. Medina,J. Micha?owski,P. Micolon,D. Nakajima,J. Niemiec,A. Nozato,M. Palatka,M. Pech,B. Peyaud,G. Pühlhofer,M. Rataj,G. Rodeghiero,G. Rojas,J. Rousselle,R. Sakonaka,P. Schovanek,K. Seweryn,C. Schultz,S. Shu,F. Stinzing,M. Stodulski,M. Teshima,P. Travniczek,C. van Eldik,V. Vassiliev,?. Wi?niewski,A. W?rnlein,T. Yoshida
Physics , 2013, DOI: 10.1117/12.2025476
Abstract: The Cherenkov Telescope Array (CTA) is the next generation very high-energy gamma-ray observatory, with at least 10 times higher sensitivity than current instruments. CTA will comprise several tens of Imaging Atmospheric Cherenkov Telescopes (IACTs) operated in array-mode and divided into three size classes: large, medium and small telescopes. The total reflective surface could be up to 10,000 m2 requiring unprecedented technological efforts. The properties of the reflector directly influence the telescope performance and thus constitute a fundamental ingredient to improve and maintain the sensitivity. The R&D status of lightweight, reliable and cost-effective mirror facets for the CTA telescope reflectors for the different classes of telescopes is reviewed in this paper.
Single-Mirror Small-Size Telescope structure for the Cherenkov Telescope Array  [PDF]
Jacek Niemiec,Jerzy Micha?owski,Micha? Dyrda,Wojciech Kochański,Jaromir Ludwin,Marek Stodulski,Pawe? Zió?kowski,Pawe? ?ychowski for the CTA Consortium
Physics , 2013,
Abstract: A single-mirror small-size (1M-SST) Davies-Cotton telescope has been proposed for the southern observatory of the Cherenkov Telescope Array (CTA) by a consortium of scientific institutions from Poland, Switzerland, and Germany. The telescope has a 4 m diameter reflector and will be equipped with a fully digital camera based on Geiger avalanche photodiodes (APDs). Such a design is particularly interesting for CTA because it represents a very simple, reliable, and cheap solution for a SST. Here we present the design and the characteristics of the mechanical structure of the 1M-SST telescope and its drive system. We also discuss the results of a finite element method analysis in order to demonstrate the conformance of the design with the CTA specifications and scientific objectives. In addition, we report on the current status of the construction of a prototype telescope structure at the Institute of Nuclear Physics PAS in Krakow.
Software design for the control system for Small-Size Telescopes with single-mirror of the Cherenkov Telescope Array  [PDF]
A. Porcelli for the CTA Consortium,for the SST-1M sub-consortium,:,W. Bilnik,J. B?ocki,L. Bogacz,J. Borkowski,T. Bulik,F. Cadoux,A. Christov,M. Cury?o,D. della Volpe,M. Dyrda,Y. Favre,A. Frankowski,?. Grudnik,M. Grudzińska,M. Heller,B. Id?kowski,M. Jamrozy,M. Janiak,J. Kasperek,K. Lalik,E. Lyard,E. Mach,D. Mandat,A. Marsza?ek,J. Micha?owski,R. Moderski,M. Rameez,T. Montaruli,A. Neronov,J. Niemiec,M. Ostrowski,P. Pa?ko,M. Pech,A. Porcelli,E. Prandini,P. Rajda,E. jr Schioppa,P. Schovanek,K. Seweryn,K. Skowron,V. Sliusar,M. Sowiński,?. Stawarz,M. Stodulska,M. Stodulski,I. Troyano Pujadas,S. Toscano,R. Walter,M. Wi?cek,A. Zagdański,K. Zi?tara,P. Zychowski
Physics , 2015,
Abstract: The Small-Size Telescope with single-mirror (SST-1M) is a 4 m Davies-Cotton telescope and is among the proposed telescope designs for the Cherenkov Telescope Array (CTA). It is conceived to provide the high-energy ($>$ few TeV) coverage. The SST-1M contains proven technology for the telescope structure and innovative electronics and photosensors for the camera. Its design is meant to be simple, low-budget and easy-to-build industrially. Each device subsystem of an SST-1M telescope is made visible to CTA through a dedicated industrial standard server. The software is being developed in collaboration with the CTA Medium-Size Telescopes to ensure compatibility and uniformity of the array control. Early operations of the SST-1M prototype will be performed with a subset of the CTA central array control system based on the Alma Common Software (ACS). The triggered event data are time stamped, formatted and finally transmitted to the CTA data acquisition. The software system developed to control the devices of an SST-1M telescope is described, as well as the interface between the telescope abstraction to the CTA central control and the data acquisition system.
Status of the Medium-Sized Telescope for the Cherenkov Telescope Array  [PDF]
Markus Garczarczyk,Stefan Schlenstedt,Louise Oakes,Ullrich Schwanke,the MST Team
Physics , 2015,
Abstract: The Cherenkov Telescope Array (CTA), is an international project for the next generation ground- based observatory for gamma-ray astronomy in the energy range from 20 GeV to 300 TeV. The sensitivity in the core energy range will be dominated by up to 40 Medium-Sized Telescopes (MSTs). The MSTs, of Davies-Cotton type with a 12 m diameter reflector are currently in the prototype phase. A full-size mechanical telescope structure has been assembled in Berlin. The telescope is partially equipped with different mirror prototypes, which are currently being tested and evaluated for performances characteristics. A report concentrating on the details of the tele- scope structure, the drive assemblies and the optics of the MST prototype will be given.
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