Tests of a third generation multianode phototube for the CDF plug shower maximum detector

The CDF experiment at Fermilab is upgrading most of the detector in preparation for run II. We report here the results of tests of the 16-channel Hamamatsu R5900-M16 photomultiplier tube, which has been chosen as the photodetector for the plug calorimeter shower maximum readout. The gain uniformity, stability, pixel uniformity, linearity, cross-talk, and quantum efficiency is found to be superior to that of earlier generations of multianode photomultiplier tubes.