A NECTAr-based upgrade for the Cherenkov cameras of the H.E.S.S. 12-meter telescopes
Abstract
The High Energy Stereoscopic System (H.E.S.S.) is one of the three arrays of imaging atmospheric Cherenkov telescopes (IACTs) currently in operation. It is composed of four 12-meter telescopes and a 28-meter one, and is sensitive to gamma rays in the energy range ~ 30 GeV – 100 TeV. The cameras of the 12-m telescopes recently underwent a substantial upgrade, with the goal of improving their performance and robustness. The upgrade involved replacing all camera components except for the photomultiplier tubes (PMTs). This meant developing new hardware for the trigger, readout, power, cooling and mechanical systems, and new software for camera control and data acquisition. Several novel technologies were employed in the cameras: the readout is built around the new NECTAr digitizer chip, developed for the next generation of IACTs; the camera electronics is fully controlled and read out via Ethernet using a combination of FPGA and embedded ARM computers; the software uses modern libraries such as Apache Thrift, ØMQ and Protocol buffers. This work describes in detail the design and the performance of the upgraded cameras.
Keywords
PMT Cameras
NECTAr
H.E.S.S
Cherenkov counter: atmosphere
upgrade
programming
performance
HESS
data acquisition
electronics: design
electronics: readout
photon: detector
detector: design
computer: communications
trigger
electrical engineering
mechanical engineering
FPGA
PMT Cameras
Gamma-ray astronomy
Cherenkov camera
High-energy instrumentation upgrade