An electromagnetic calorimeter for the small angle regions of the collider detector at Fermilab

Abstract

Two large electromagnetic calorimeters have been built for the Collider Detector at Fermilab (CDF). These have been designed for use in the small angle regions in both the proton and the antiproton beam directions. Each calorimeter consists of 30 sampling layers of proportional tube chambers with cathode pad readout separated by lead sheets for a total thickness of 25.5 radiation lengths. Each proportional tube chamber is constructed using a novel technique in which the insulating side of the cathode pad board is bonded to the proportional tube walls using resistive epoxy. The measured energy response of the calorimeter is linear up to 160 GeV, and the measured energy resolution, $\text{σ}{}_{\mathrm{E}}\text{E}$, is approximately $\text{25\%}\text{√E + 0.5\%}$. The position resolution for single electrons varies between 1 and 4 mm depending on location in the calorimeter. The calorimeter offers good $\text{e}\text{π}$ discrimination, where typically the pion misidentification probability $\text{ƒ}{}_{\mathrm{<mtext>\pi \; \to \; </mtext><mtext>e</mtext>}}\text{< 0.5\%}$ for an electron identification efficiency ϵ90%.