Cherenkov Telescope Array (CTA)

Design of nanosecond Light Flasher for CTA Telescope

(In collaboration with SINP)

The Cherenkov Telescope Array (CTA) project is an international collaboration aimed to the VHE gamma ray astrophysics in the energy range 30 GeV-100 TeV. The CTA will consist of two arrays of Cherenkov telescopes, one for each hemisphere, consisting of telescopes of three different sizes. The Large Size Telescope (LST) camera consisting of array of photomultiplier tubes (PMTs), will require an accurate and systematic calibration over a wide dynamic range. A calibration device has been designed to calibrate the camera pixels (PMTs) of LST telescope.

Calibration device is required to be a self-monitoring system producing 3-4 ns FWHM light pulses from single photo-electron (pe) to at least 1000 pe. The calibration system will produce a fast and uniform light pulse in a wavelength range close to the peak of the Cherenkov spectrum. The light pulse produced by the calibration system will be utilized for flat-fielding the camera pixels and for determining the adc/pe ratio of the pixel chain. The calibration system will produce a light pulses of different intensity to determine the linearity of the system. We have designed and developed prototype calibration device according to this requirements.

The various components of Calibration device are:

• UV LASER of 355 nm wavelength with 400 ps pulse width

• Diffuser sphere

• Two sets of neutral density filters

• Temperature controller

• Microcontroller

(Ref: M. Palatiello et al., Proceedings of 35th ICRC at Busan, Korea, during 12-20 July, 2017)


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