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

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posted on 01.02.2019, 15:19 by J Zorn, R White, JJ Watson, TP Armstrong, A Balzer, M Barcelo, D Berge, R Bose, AM Brown, M Bryan, PM Chadwick, P Clark, H Costantini, G Cotter, L Dangeon, M Daniel, A De Franco, P Deiml, G Fasola, S Funk, M Gebyehu, J Gironnet, JA Graham, T Greenshaw, JA Hinton, M Kraus, JS Lapington, P Laporte, SA Leach, O Le Blanc, A Malouf, P Molyneux, P Moore, H Prokoph, A Okumura, D Ross, G Rowell, L Sapozhnikov, H Schoorlemmer, H Sol, M Stephan, H Tajima, L Tibaldo, G Varner, A Zink
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 γ-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 × 6 mm2 pixels, leading to a low-cost (∼150 k€), compact (0.5 m × 0.5 m), and light (∼45 kg) camera with 2048 pixels providing a camera FoV of ∼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 γ-ray energy range of 1–300 TeV, and at impact distances up 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 ∼900 Hz. The first prototype, CHEC-M, based on multi-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.

Funding

This work was conducted in the context of the CTA GCT project. We gratefully acknowledge financial support from the agencies and organisationslisted here: http://www.cta-observatory.org/consortium_acknowledgments. Furthermore, we thank the Paris Observatory as well as the DT-INSU for their support during the on-sky campaigns in Meudon. This study was also supported by JSPS KAKENHI Grant Numbers JP17H04838, JP25610040, JP15H02086, and JP23244051. A. Okumura was supported by a Grant-in-Aid for JSPS Fellows

History

Citation

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2018, 904, pp. 44-63

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

AM (Accepted Manuscript)

Published in

Nuclear Instruments and Methods in Physics Research

Publisher

Elsevier for North-Holland

issn

0168-9002

Acceptance date

27/06/2018

Copyright date

2018

Available date

04/07/2019

Publisher version

https://www.sciencedirect.com/science/article/pii/S0168900218308143?via=ihub

Notes

The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.

Language

en