Student : TSIAHINA Adellain
Advisor : JEAN Pierre, OLIVE Jean-François
Start : 2017
Group : GAHEC
The major facilities of very high energy gamma ray telescope arrays with
the imaging atmospheric Cherenkov technique (i.e. CANGAROO, HEGRA, HESS,
MACE, MAGIC and VERITAS) host up to a maximum of five individual
telescopes. The Cherenkov Telescope Array (CTA) Observatory is designed
to detect gamma rays with more than 100 telescopes. For achieving a
large energy range detection, small-sized, medium-sized and large-sized
telescopes (with diameters of 4 m, 12 m and 23 m respectively), will be
located in the northern and southern hemispheres. They will cover an
energy range of 20 GeV to 300 TeV. More than 30 countries are involved
in various activities ranging from construction to scientific
development of the facility. The NectarCAM is one of the cameras for the
medium-sized telescopes which covers the 100 GeV-30 TeV range. It
contains 1855 pixels mounted on a surface of 6 m2 and has a modular
design. All the 265 modules of the NectarCAM contains 7 photomultiplier
tubes with their power supply and preamplification which is connected to
an interface board that allows them to communicate with the rest of the
camera. The design, development and the production of the modules is
under responsability of IRAP. When manufacturing them, we must ensure
that they are valid and fulfills the requirements of the CTA consortium.
My thesis work is to implement a test bench and then studying it,
characterizing it and calibrating it to control the quality and
scientific performance of the modules. After having calibrated the gains
of the pixels of the detection units of a module, the impulse response,
the noise level, the stability within night sky background noise, the
resolution and the determination of the various defects of the
photodetectors, characterize the performances of each detector before
being integrated into the camera. The test bench has enabled us to get
the performances measurements of 61 modules for the NectarCAM prototype
that has been mounted on a protoype of medium-sized telescope in
Adlershof (Germany). These tests showed that scientific performances
fulfill the requirements. The test bench was upgraded for the analysis
of the production of the modules for the qualification model of the
camera and we discussed the results we obtained compared to NectarCAM
requirements. The qualification model will be the first camera installed
at the CTA north site in La Palma, Spain.