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Found in: osebi
Keywords: Cherenkov Telescope Array (CTA), Large Size Telescopes (LST), imaging camera, slow control board (SCB)
Published: 21.03.2016; Views: 1877; Downloads: 122
Fulltext (4,05 MB)

Found in: osebi
Keywords: Cherenkov Telescope Array (CTA), medium-sized telescopes (MST), imaging camera, NectarCAM design, NECTAr ASIC, Switched Capacitor Array
Published: 24.03.2016; Views: 2155; Downloads: 169
Fulltext (4,86 MB)

Abstract: The azimuthal asymmetry in the risetime of signals in Auger surface detector stations is a source of information on shower development. The azimuthal asymmetry is due to a combination of the longitudinal evolution of the shower and geometrical effects related to the angles of incidence of the particles into the detectors. The magnitude of the effect depends upon the zenith angle and state of development of the shower and thus provides a novel observable, (secθ)max, sensitive to the mass composition of cosmic rays above 3×1018  eV. By comparing measurements with predictions from shower simulations, we find for both of our adopted models of hadronic physics (QGSJETII-04 and EPOS-LHC) an indication that the mean cosmic-ray mass increases slowly with energy, as has been inferred from other studies. However, the mass estimates are dependent on the shower model and on the range of distance from the shower core selected. Thus the method has uncovered further deficiencies in our understanding of shower modeling that must be resolved before the mass composition can be inferred from (secθ)max.
Found in: osebi
Keywords: ultra-high energy cosmic rays (UHECR), UHECR mass composition, Pierre Auger Observatory, extensive air showers, Auger Surface Detector signals risetime, azimuthal symmetry
Published: 15.04.2016; Views: 2555; Downloads: 0
Fulltext (698,19 KB)

Abstract: This master thesis describes characterization of Silicon photomultipliers (SiPM) for the upgrade of large size telescope (LST) camera at Cherenkov telescope array (CTA). Upon the construction, CTA will be the largest and most sensitive facility for detection of very-high energy (VHE, > 30 GeV) gamma-rays ever. It will use three different sizes of telescopes, where small and medium telescopes camera will be SiPM based from the beginning, but LST camera is planned to get SiPM based camera with frst upgrade. Camera upgrade is among others also being developed at University of Padovas Department of Physics and Astronomy (INFN). Due to limitations of their laboratory characterization of prototypes is done at Institute Jooef Stefan in Ljubljana, where I measured breakdown voltage of and determined photon detection effciency depending on angle of photon arrival. This information is important for determining which SiPM is best for CTA telescopes.
Found in: osebi
Keywords: Silicon photomultiplier, SiPM, CTA
Published: 03.05.2017; Views: 3272; Downloads: 78
Fulltext (14,05 MB)

Abstract: The Cherenkov Telescope Array (CTA) is the next generation ground-based observatory for gamma-ray astronomy at very-high energies. Employing more than 100 (north and south sites) Imaging Atmospheric Cherenkov Telescopes in the northern and southern hemispheres, it was designed to reach unprecedented sensitivity and energy resolution. Understanding and correcting for systematic biases on the absolute energy scale and instrument response functions will be a cru- cial issue for the performance of CTA. The Montpellier group and the Spanish/Italian/Slovenian collaboration are currently building two Raman LIDAR prototypes for the online atmospheric cal- ibration along the line-of-sight of the CTA. Requirements for such a solution include the ability to characterize aerosol extinction at two wavelengths to distances up to 30 km with an accuracy better than 5%, within exposure time scales of about a minute, steering capabilities and close interaction with the CTA array control and data acquisition system as well as other auxiliary in- struments. Our Raman LIDARs have design features that make them different from those used in atmospheric science and are characterized by large collecting mirrors (∼2.5 m 2 ), liquid light- guides that collect the light at the focal plane and transport it to the readout system, reduced acquisition time and highly precise Raman spectrometers. The Raman LIDARs will participate in a cross-calibration and characterization campaign of the atmosphere at the CTA North site at La Palma, together with other site characterization instruments. After a one-year test period there, an in-depth evaluation of the solutions adopted by the two projects will lead to a final Raman LIDAR design proposal for both CTA sites.
Found in: osebi
Keywords: Raman lidar atmospheric calibration Cherenkov Telescope Array
Published: 29.08.2019; Views: 792; Downloads: 35
Fulltext (1,29 MB)