Resistive Anode Photomultiplier Tube Optimum Operating Conditions for Photon Correlation Experiments

One of the most important new photon-counting two-dimensional imaging detectors developed in the last few years is a microchannel plate photomultiplier tube having a resistive anode readout. Some of the details of the design and performance characteristics of this detector have been described by Firmani (3) and Rees (5). This type of imaging photon detector (IPD) has been used by Dainty, et al (6), to perform photon correlation experiments on dynamic speckle. An ITT version, #F4146M, of this IPD has been tested with a Surface Sciences Instruments model 2401 position computer. Limiting resolution, relative counting efficiency, and linearity have been measured under a variety of operational conditions, and optimum values have been determined. These conditions are presented and discussed in detail. The limiting spatial resolution varies from about 50 um FWHM at the center, to about 65 um FWHM near the edge of the IPD's 25 mm active diameter. The relative counting efficiency is found to be optimized for the same general operating conditions that produce the best spatial resolution, and the IPD and Surface Sciences Instruments position computer system is linear for count rates up to at least 1E4 cps.