No abstract

We describe two test benches that were designed and constructed to perform a set of acceptance tests for about 1200 Photomultiplier Tube (PMT) units to be installed in the surface scintillation detectors of AugerPrime. Besides possessing robustness, long-term reliability, and low power consumption, each PMT-unit requires a dynamic range wide enough to cover signals ranging from a single to more than 20,000 minimum ionizing particles with not more than 5 % deviation from linear response. This posed a particular challenge which was met by combining a specially selected 1.5" PMT type with a custom made Cockcroft Walton type base. The characteristics of the PMT units and qualification results obtained for a large quantity of tested units will be presented and discussed. Besides measuring the gain and linearity for each PMT-unit for different supply voltages, in a sub-sample of about 10 %, we also measured the quantum-efficiency of the photocathode as a function of wavelength as well as its homogeneity across the full photocathode area with 1 mm spatial resolution. The latter is of importance because of the fiber-optical readout of the scintillation detectors.

In space Earth Observation related projects, Sun Simulators are regular used for on-ground calibrations of the flight instruments. Instrument radiometric calibration is established by illuminating the on-board diffuser(s) via the Sun port in irradiance configuration and an external OGSE calibrated diffuser for the radiance configuration via the Earth Port. Usually, Sun Simulator designs are complex containing multiple coated mirrors, and its implementation requires large volume and mass. The paper will present an elegant and innovative concept of building such a Sun Simulator using minimum elements. The new concept consists of three major units: the illumination unit, the diffuser unit and the collimator unit. All units have been purchased, mounted on an optical table and aligned. Finally, preliminary performance tests of the Sun Simulator Breadboard are presented. The Breadboard proves the concept and also allows scaling to different instrument needs.