A Major Upgrade of the H.E.S.S. Cherenkov Cameras

I Lypova ,Marko Kossatz,Markus Schade,Tobias Gräber,Emmanuel Moulin,Albert Jahnke,V Lefranc ,A Kretzschmann ,D Šálek ,R Simoni ,É Delagnes ,M Füßling ,H Lüdecke ,H Leich ,S Ohm ,F Brun ,J A Hinton ,J Thornhill ,B Giebels ,S Klepser ,M Penno ,T Ashton ,C Stegmann ,G Giavitto ,P Nayman ,T Chaminade ,J F Glicenstein ,A Balzer ,D Berge ,C Steppa ,P Manigot ,G Fontaine ,M De Naurois ,Thomas Schwab,D Ross ,V Marandon ,François Toussnel

doi:10.1051/epjconf/201713603002

Abstract

The High Energy Stereoscopic System (H.E.S.S.) is an array of imaging atmospheric Cherenkov telescopes (IACTs) located in Namibia. It was built to detect Very High Energy (VHE, >100 GeV) cosmic gamma rays, and consists of four 12 m diameter Cherenkov telescopes (CT1-4), built in 2003, and a larger 28 m telescope (CT5), built in 2012. The larger mirror surface of CT5 permits to lower the energy threshold of the array down to 30 GeV. The cameras of CT1-4 are currently undergoing an extensive upgrade, with the goals of reducing their failure rate, reducing their readout dead time and improving the overall performance of the array. The entire camera electronics has been renewed from ground-up, as well as the power, ventilation and pneumatics systems, and the control and data acquisition software. Technical solutions forseen for the next-generation Cherenkov Telescope Array (CTA) observatory have been introduced, most notably the readout is based on the NECTAr analog memory chip. The camera control subsystems and the control software framework also pursue an innovative design, increasing the camera performance, robustness and flexibility. The CT1 camera has been upgraded in July 2015 and is currently taking data; CT2-4 will upgraded in Fall 2016. Together they will assure continuous operation of H.E.S.S at its full sensitivity until and possibly beyond the advent of CTA. This contribution describes the design, the testing and the in-lab and on-site performance of all components of the newly upgraded H.E.S.S. camera.

Highlights

The H.E.S.S. experiment is situated at 1800 m hight in the Khomas Highland of Namibia
The dead time of the old H.E.S.S. phase I camera was ∼450 μs, which is much bigger than the dead time of the modern CT5 (∼15 μs) and is not suitable for such high rates
The electronics and cabling of the cameras are renewed during the upgrade. As it is seen from figure 1 most of the electronic components of the camera were replaced

Summary

Introduction

The H.E.S.S. experiment is situated at 1800 m hight in the Khomas Highland of Namibia. The larger mirror of the new telescope lowered the array energy threshold from ∼100 GeV to ∼30 GeV and increased the array trigger rate from (200 - 300) Hz to more than 1.5 kHz. The dead time of the old H.E.S.S. phase I camera was ∼450 μs, which is much bigger than the dead time of the modern CT5 (∼15 μs) and is not suitable for such high rates. Thereby, one of the main goals of the H.E.S.S. phase I upgrade is to reduce the dead time and to increase the number of recorded stereoscopic events. The electronics and cabling of the cameras are renewed during the upgrade.

Results

Conclusion