Evaluation of candidate photomultiplier tubes for the upgrade of the CDF end plug calorimeter

Abstract

The Collider Detector at Fermilab is upgrading its end plug calorimeter from a gas detector system to one using scintillating tiles read out through wavelength shifting fibers. This upgrade is required to take advantage of the increase in luminosity which the Tevatron will provide in the future. The tile-fiber calorimeter, which is longitudinally segmented into electromagnetic and hadronic sections, will be read out through 1824 photomultiplier tubes. The performance requirements of the calorimeter demand that the PMTs have good response to light in the 500 nm region, provide adequate amplification for signals from minimum ionizing particles, provide linear response for peak anode currents up to 25 mA at a gain of 5×10 4, and fit into the restricted space at the rear of the plugs. For convenience, we also desire a single PMT and base combination be used for the electromagnetic and hadron calorimeters even though the required gains in these sections differ by a factor of 10. This paper describes the evaluation process used to determine the adequacy of the commercially available PMTs which appeared to meet our performance requirements.