A Brief Technical History of the Large Area Picosecond Photodetector (LAPPD) Collaboration
The Large Area Picosecond PhotoDetector (LAPPD) Collaboration was formed in 2009 to develop large area photodetectors capable of time resolutions measured in pico seconds, with accompanying sub millimeter spatial resolution. During the next three and one half years the Collaboration developed the LAPPD design of 20 x 20 cm modules with gains greater than $10^7$ and non uniformity less than $15\ time resolution less than 50 psec for single photons and spatial resolution of 700~microns in both lateral dimensions. We describe the R\&D performed to develop large area micro channel plate glass substrates, resistive and secondary emitting coatings, large area bialkali photocathodes, and RF capable hermetic packaging. In addition, the Collaboration developed the necessary electronics for large systems capable of precise timing, built up from a custom low power 15 GigaSample/sec waveform sampling 6 channel integrated circuit and supported by a two level modular data acquisition system based on Field Programmable Gate Arrays for local control, data sparcification, and triggering. We discuss the formation, organization, and technical successes and short comings of the Collaboration. The Collaboration ended in December 2012 with a transition from R\&D to commercialization.