Patrick Nayman - Academia.edu (original) (raw)

Papers by Patrick Nayman

Astroparticle Physics, 2020

The High Energy Stereoscopic System (H.E.S.S.) is one of the three arrays of imaging atmospheric ... more The High Energy Stereoscopic System (H.E.S.S.) is one of the three arrays of imaging atmospheric Cherenkov telescopes (IACTs) currently in operation.

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017), 2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017), 2018

The 14 years old cameras of the H.E.S.S. 12-m telescopes have been upgraded in 2015/2016, with th... more The 14 years old cameras of the H.E.S.S. 12-m telescopes have been upgraded in 2015/2016, with the goals of reducing the system failure rate, reducing the dead time and improving the overall performance of the array. This conference contribution describes the various tests that were carried out on the cameras and their sub-components both in the lab and on site. It also gives an overview of the commissioning and calibration procedures adopted during and after the installation, including e.g. flat-fielding and trigger threshold scans. Finally, it reports in detail about the overall performance of the four new H.E.S.S. I cameras, using very recent data.

EPJ Web of Conferences, 2017

The High Energy Stereoscopic System (H.E.S.S.) is an array of imaging atmospheric Cherenkov teles... more 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.

AIP Conference Proceedings, 2017

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2006

2006 IEEE Nuclear Science Symposium Conference Record, 2006

The H.E.S.S.-I front-end electronics is based on the ARSO chip, a multigigahertz sampler and anal... more The H.E.S.S.-I front-end electronics is based on the ARSO chip, a multigigahertz sampler and analog memory used as a level-1 circular buffer. In the future H.E.S.S.-II, the energy threshold will be decreased as low as 10 GeV. This will require a much higher acquisition rate capability and a larger dynamic range incompatible with the electronics developed for HESS-I. These constraints

AIP Conference Proceedings, 2012

The European astroparticle physics community aims to design and build the next generation array o... more The European astroparticle physics community aims to design and build the next generation array of Imaging Atmospheric Cherenkov Telescopes (IACTs), that will benefit from the experience of the existing H.E.S.S. and MAGIC detectors, and further expand the very-high energy astronomy domain. In order to gain an order of magnitude in sensitivity in the 10 GeV to 4 100 TeV range, the Cherenkov Telescope Array (CTA) will employ 50-100 mirrors of various sizes equipped with 1000-4000 channels per camera, to be compared with the 6000 channels of the final H.E.S.S. array. A 3-year program, started in 2009, aims to build and test a demonstrator module of a generic CTA camera. We present here the NECTAr design of front-end electronics for the CTA, adapted to the trigger and data acquisition of a large IACTs array, with simple production and maintenance. Cost and camera performances are optimized by maximizing integration of the front-end electronics (amplifiers, fast analog samplers, ADCs) in an ASIC, achieving several GS/s and a few ms readout dead-time. We present preliminary results and extrapolated performances from Monte Carlo simulations.

2011 IEEE Nuclear Science Symposium Conference Record, 2011

H.E.S.S. and MAGIC experiments have demonstrated the high level of maturity of Imaging Atmospheri... more H.E.S.S. and MAGIC experiments have demonstrated the high level of maturity of Imaging Atmospheric Cherenkov Telescopes (IACTs) dedicated to very-high-energy gamma ray astronomy domain. The astroparticle physics community is preparing the next generation of instruments, with sensitivity improved by an order of magnitude in the 10 GeV to 100 TeV range. To reach this goal, the Cherenkov Telescope Array (CTA)

Ground-based and Airborne Instrumentation for Astronomy VI, 2016

The High Energy Stereoscopic System (H.E.S.S.) is an array of five imaging atmospheric Cherenkov ... more 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.