Development of a high efficient PMT Winston-cone system for fluorescence measurement of extensive air showers

Abstract

Fluorescence telescopes are important instruments to measure extensive air showers initiated by ultra-high energetic cosmic rays. They measure the longitudinal profile of the energy deposited in the atmosphere by detecting the de-excitation of nitrogen molecules in the UV-range. In recent years the development of photomultiplier tubes (PMTs) has led to an increase of more than 30% in photon detection sensitivity, by using newly developed super-bialkali (SBA) photocathodes. Thus, the telescopes can detect even fainter signals over a larger area resulting in a significant increase in aperture. To develop telescopes for a next generation cosmic ray observatory, the camera needs to have a maximal sensitive area in the focal plane. Winston cones can efficiently cover the dead area between the photocathodes of the PMTs. Such a highly efficient system composed of an SBA PMT and Winston cone has been developed, based on the design of the fluorescence telescopes of the Pierre Auger Observatory. This contribution shows the development of the optical detection system and first tests in one of the fluorescence telescopes.

A photomultiplier tube test stand and on-site measurements to characterise the performance of Photonis XP3062 photomultiplier tubes at increased background light conditions and lower gain

“…where e is the elementary charge, I A the anode current, ρ the quantum efficiency, and G the gain of the PMT. Using the nominal FD gain and the quantum efficiency ρ of ∼29% at 375 nm [14], this results in…”