A scanning device for spatial quantum efficiency measurements of photomultipliers tubes

TL;DR

This paper introduces a precise, scalable measurement setup for assessing the quantum efficiency of large-area photomultiplier tubes across a broad wavelength range, improving accuracy and repeatability over existing methods.

Contribution

The paper presents a novel, high-precision quantum efficiency measurement system utilizing a 2D motorized stage and calibrated photodiodes, capable of testing large PMTs with enhanced accuracy.

Findings

High precision in QE measurement across 250-1100 nm

Effective technical refinements improve measurement reliability

Capability to characterize large-area PMTs up to 10 inches

Abstract

This paper presents a quantum efficiency measurement setup based on a 2D motorized stage, a wide spectrum xenon lamp, a beam splitter system, and two calibrated photo-diodes for measuring the quantum efficiency (QE) of photomultiplier tubes (1 to 10 inches). We will demonstrate the effectiveness of technical refinements on the measurements procedures over some existing setups already shown in literature. The large area covered by the 2D stages permit to study the quantum efficiency of PMTs with diameter up to ten inches. The results obtained will show the high precision and accuracy in characterizing the quantum efficiency versus wavelength over the range of 250 nm to 1100 nm and along the photo-catode surface. The setup monitors the light intensity synchronously with the output current yield from photosensors under test. This ensures the accuracy and repeatability of the measurements. The motorized stage allows precise positioning of the light source with respect to the active area. The emission spectrum of the xenon lamp provides a broad range of illumination in terms of dynamics and wavelength span.