EVALUATION OF CANDIDATE PHOTOMULTIPLIER TUBES FOR THE UPGRADE OF THE CDF END PLUG CALORIMETER

The Collider Detector at Fermilab is upgrading its end plug calorimete r 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 provid e in the future. The tile-fiber calorimeter; which is longitudinally s egmented into electromagnetic and hadronic sections, will be read out through 1824 photomultiplier tubes. The performance requirements of th e 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 u p to 25 mA at a gain of 5 x 10(4), and fit into the restricted space a t the rear of the plugs. For convenience, we also desire a single PMT and base combination be used for the electromagnetic and hadron calori meters even though the required gains in these sections differ by a fa ctor of 10. This paper describes the evaluation process used to determ ine the adequacy of the commercially available PMTs which appeared to meet our performance requirements. (C) 1998 Published by Elsevier Scie nce B.V. All rights reserved.