The XY Scanner - A Versatile Method of the Absolute End-to-End Calibration of Fluorescence Detectors

Discussion timeslot (ZOOM-Meeting): 21. July 2021 - 12:00
ZOOM-Meeting URL: https://desy.zoom.us/j/92210078166
ZOOM-Meeting ID: 92210078166
ZOOM-Meeting Passcode: ICRC2021
Corresponding Session: https://icrc2021-venue.desy.de/channel/13-New-Instrumentation-and-Tools-for-EAS-Detection-CRI/92
Live-Stream URL: https://icrc2021-venue.desy.de/livestream/Discussion-03/4

Abstract:
'One of the crucial detector systems of the Pierre Auger Observatory is the fluorescence detector composed of 27 large-aperture wide-angle Schmidt telescopes.rnIn the past, these telescopes were absolutely calibrated by illuminating the whole aperture with a uniform large-diameter light source.rnThis absolute calibration was performed roughly once every three years, while a relative calibration was performed on a nightly basis.rnIn this contribution, a new technique for an absolute end-to-end calibration of the fluorescence telescopes is presented.rnFor this technique, a portable calibrated light source mounted on a rail system is moved across the aperture of each telescope, instead of illuminating the whole aperture at once.rnA dedicated setup for the absolute calibration of the light source has been built, which uses a combination of NIST traceable photodiodes to measure the mean intensity and a PMT for pulse-to-pulse stability tracking.rnAs a result of these complementary measurements, the pulse-to-pulse light source intensity can be known to the 3.5% uncertainty level.rnThe analysis of the readout of the PMT camera at each position of the light source together with the knowledge of the light source emission provides an absolute end-to-end calibration of the telescope.rnWe will give a brief overview of this novel calibration method and its current status, as well as preliminary results from the measurement campaigns performed so far.'

Authors: Christoph Schäfer | for the Pierre Auger-Collaboration
Collaboration: Auger

Indico-ID: 591
Proceeding URL: https://pos.sissa.it/395/220