Our contribution presents a high bandwidth platform that implements traffic aggregation and switching capabilities for the Cherenkov telescope array (CTA) cameras. Our proposed system integrates two different data flows: a unidirectional one from the cameras to an external server and a second one, fully configurable dedicated to configuration and control traffic for the camera management. The former requires high bandwidth mechanisms to be able to aggregate several 1 gigabit Ethernet links into one high speed 10 gigabit Ethernet port. The latter is responsible for providing routing components to allow a control and management path for all the elements of the cameras. Hence, a simple, efficient, and flexible routing mechanism has been implemented avoiding complex circuitry that impacts in the system performance. As a consequence, an asymmetric network topology allows high bandwidth communication and, at the same time, a flexible and cost-effective implementation. In our contribution, we analyze the camera requirements and present the proposed architecture. Moreover, we have designed several evaluation tests to demonstrate that our solution fulfills the CTA project needs. Finally, we illustrate the general possibilities of the proposed solution for other data acquisition applications and the most promising futures lines of research are discussed.
The Gamma-ray Cherenkov Telescope (GCT) is one of the telescopes proposed for the Small Sized Telescope (SST) section of CTA. Based on a dual-mirror Schwarzschild-Couder design, which allows for more compact telescopes and cameras than the usual single-mirror designs, it will be equipped with a Compact High-Energy Camera (CHEC) based on silicon photomultipliers (SiPM). In 2015, the GCT prototype was the first dual-mirror telescope constructed in the prospect of CTA to record Cherenkov light on the night sky. Further tests and observations have been performed since then. This report describes the current status of the GCT, the results of tests performed to demonstrate its compliance with CTA requirements, and the optimisation of the design for mass production. The GCT collaboration, including teams from Australia, France, Germany, Japan, the Netherlands and the United Kingdom, plans to install the first telescopes on site in Chile for 2019-2020 as part of the CTA pre-production phase.
Proc. SPIE. 9908, Ground-based and Airborne Instrumentation for Astronomy VI
KEYWORDS: Telescopes, Electronics, Imaging systems, Imaging systems, Cameras, Calibration, Field programmable gate arrays, Control systems, Control systems, Data acquisition, Analog electronics, Atmospheric Cherenkov telescopes
The High Energy Stereoscopic System (H.E.S.S.) is an array of five imaging atmospheric Cherenkov telescopes, sensitive to cosmic gamma rays of energies between ~30 GeV and several tens of TeV. Four of them started operations in 2003 and their photomultiplier tube (PMT) cameras are currently undergoing a major upgrade, with the goals of improving the overall performance of the array and reducing the failure rate of the ageing systems. With the exception of the 960 PMTs, all components inside the camera have been replaced: these include the readout and trigger electronics, the power, ventilation and pneumatic systems and the control and data acquisition software. New designs and technical solutions have been introduced: the readout makes use of the NECTAr analog memory chip, which samples and stores the PMT signals and was developed for the Cherenkov Telescope Array (CTA). The control of all hardware subsystems is carried out by an FPGA coupled to an embedded ARM computer, a modular design which has proven to be very fast and reliable. The new camera software is based on modern C++ libraries such as Apache Thrift, ØMQ and Protocol buffers, offering very good performance, robustness, flexibility and ease of development. The first camera was upgraded in 2015, the other three cameras are foreseen to follow in fall 2016. We describe the design, the performance, the results of the tests and the lessons learned from the first upgraded H.E.S.S. camera.