A measurement of the energy and timing resolution of GlueX Forward Calorimeter using an electron beam

TL;DR

This study measures the energy and timing resolution of the GlueX Forward Calorimeter using an electron beam, demonstrating it meets design goals and provides precise timing for background discrimination.

Contribution

First measurement of the GlueX Forward Calorimeter's energy and timing resolution at low electron energies near the design sensitivity.

Findings

Energy resolution ranges from 20% to 14% for 110-260 MeV electrons.

Timing resolution achieved is 0.38 ns for a 100 mV pulse.

Detector performance meets design specifications.

Abstract

The performance of the GlueX Forward Calorimeter was studied using a small version of the detector and a variable energy electron beam derived from the Hall B tagger at Jefferson Lab. For electron energies from 110 MeV to 260 MeV, which are near the lower-limits of the design sensitivity, the fractional energy resolution was measured to range from 20% to 14%, which meets the design goals. The use of custom 250 MHz flash ADCs for readout allowed precise measurements of signal arrival times. The detector achieved timing resolutions of 0.38 ns for a single 100 mV pulse, which will allow timing discrimination of photon beam bunches and out-of-time background during the operation of the GlueX detector.