Position-sensitive vacuum photon detectors

This article reviews the principles, performance and limitations of position-sensitive vacuum photon detectors which find applications in high-energy physics experiments. Particular emphasis is devoted to multi-anode photo-multiplier tubes, devices based on micro-channel plates and hybrid photon detectors. Over the past 25 years, innovation in industrial environments, research centres and universities has led to the invention and consequent optimization of a number of position-sensitive photon detectors. Miniaturization of known principles and components or the smart combination of established concepts allowed to build new classes of finely-segmented photodetectors which in turn enabled new applications in high-energy physics, but also elsewhere. The imaging of Cherenkov light in hostile hadron environments like at the CERN Large Hadron Collider is perhaps one of the most demanding applications which would not have been possible without this breakthrough.