Hamburg 2016 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 38: Gammaastronomie II

T 38.2: Vortrag

Montag, 29. Februar 2016, 17:00–17:15, VMP9 SR 27

Upgrade of the MAGIC telescopes single wavelength micro power LIDAR system — •Dominik Müller for the MAGIC collaboration — Max-Planck-Institut für Physik, München

Since 2011 a single wavelength LIDAR system is operated alongside the observations of the MAGIC telescopes. It is used for real-time monitoring of the atmospheric transmission and for detecting cloud layers within the field of view of MAGIC. The system uses a pulsed Nd:YAG laser with 532nm wavelength and a pulse energy of 5μJ as transmitter. The receiver is mounted to a 60cm spherical single mirror telescope with a F/D ratio of 2.5. To compensate for the low light intensities a sensitive detector with the capability of single photon detection as well as charge integration is needed. For this purpose, a hybrid photo diode with a peak quantum efficiency of 55% an a pulse width of 2.5ns is used in a custom designed detector. The analog signal is recorded by a computer mounted 8-bit FADC with 200MS/s. A signal analysis algorithm converts the LIDAR return signal into a number of single photoelectron counts per range bin. The atmospheric transmission is calculated by fitting a Rayleigh back-scattering model with a sliding window. The resulting transmission profile is used to correct the MAGIC gamma ray data for adverse weather conditions. After five years of data taking the MAGIC LIDAR system is upgraded with a stronger laser and a new detector unit in order to extend the measurement range and to optimize the operation.