Characterisation and testing of CHEC-M-A camera prototype for the small-sized telescopes of the Cherenkov telescope array



Zorn, J, White, R, Watson, JJ, Armstrong, TP, Balzer, A, Barcelo, M, Berge, D, Bose, R, Brown, AM, Bryan, M
et al (show 35 more authors) (2018) Characterisation and testing of CHEC-M-A camera prototype for the small-sized telescopes of the Cherenkov telescope array. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 904. 44 - 63.

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Abstract

The Compact High Energy Camera (CHEC) is a camera design for the Small-Sized Telescopes (SSTs; 4 m diameter mirror) of the Cherenkov Telescope Array (CTA). The SSTs are focused on very-high-energy gamma-ray detection via atmospheric Cherenkov light detection over a very large area. This implies many individual units and hence cost-effective implementation, as well as shower detection at large impact distance, and hence large field of view (FoV), and efficient image capture in the presence of large time gradients in the shower image detected by the camera. CHEC relies on dual-mirror optics to reduce the plate-scale and make use of 6 x 6 mm(2) pixels, leading to a low-cost (similar to 150 k(sic)), compact (0.5 m x 0.5 m), and light (similar to 45 kg) camera with 2048 pixels providing a camera FoV of similar to 9 degrees. The CHEC electronics are based on custom TARGET (TeV array readout with GSa/s sampling and event trigger) application-specific integrated circuits (ASICs) and field programmable gate arrays (FPGAs) sampling incoming signals at a gigasample per second, with flexible camera-level triggering within a single backplane FPGA. CHEC is designed to observe in the gamma-ray energy range of 1-300 TeV, and at impact distances up to similar to 500 m. To accommodate this and provide full flexibility for later data analysis, full waveforms with 96 samples for all 2048 pixels can be read out at rates up to similar to 900 Hz. The first prototype, CHEC-M, based on mull-anode photomultipliers (MAPMs) as photosensors, was commissioned and characterised in the laboratory and during two measurement campaigns on a telescope structure at the Paris Observatory in Meudon. In this paper, the results and conclusions from the laboratory and on-site testing of CHEC-M are presented. They have provided essential input on the system design and on operational and data analysis procedures for a camera of this type. A second full-camera prototype based on Silicon photomultipliers (SiPMs), addressing the drawbacks of CHEC-M identified during the first prototype phase, has already been built and is currently being commissioned and tested in the laboratory.

Item Type: Article
Uncontrolled Keywords: Gamma-rays, Imaging atmospheric Cherenkov telescopes, Cherenkov telescope array, Full-waveform readout
Depositing User: Symplectic Admin
Date Deposited: 13 May 2019 15:26
Last Modified: 09 Sep 2022 11:50
DOI: 10.1016/j.nima.2018.06.078
Open Access URL: http://dro.dur.ac.uk/25428/
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3041086