Response Magnitude Uniformity of Two Commercial 5'' Photomultiplier Tubes

We are investigating the magnitude of the signal response of two photomultiplier tubes, the Hamamatsu R1250 and the Adit B133D01, to characterize the response across the full spatial extent of each tube. The tubes are mounted on translational stages to direct an attenuated light pulse through a pinhole onto regularly spaced regions of the photocathode. Each pulse is simultaneously measured by a fast photodiode to be used as a reference for the magnitude of the photomultiplier tube response. Peak and area responses will both be considered. Together with the timing characteristics previously studied, this research will provide a more complete description of the response characteristics of these photomultiplier tubes across the entire photocathode.