  Hamamatsu single anode R7761 and multi-anode R5900-00-M16 Photomultiplier
Tubes have been characterized for use in a Secondary Emission (SE) Ionization
Calorimetry study. SE Ionization Calorimetry is a novel technique to measure
electromagnetic shower particles in extreme radiation environments. The
different operation modes used in these tests were developed by modifying the
conventional PMT bias circuit. These modifications were simple changes to the
arrangement of the voltage dividers of the baseboard circuits. The PMTs with
modified bases, referred to as operating in SE mode, are used as an SE detector
module in an SE calorimeter prototype, and placed between absorber materials
(Fe, Cu, Pb, W, etc.). Here, the technical design of different operation modes,
as well as the characterization measurements of both SE modes and the
conventional PMT mode are reported.
