Measurement of the energy resolution and related properties of an SCG1-C scintillation glass shower counter array for 1 to 25 GeV positrons

The measurement of the energy resolution of a 4 x 4 array of SCG1-C scintilation glass counters exposed to positrons in the energy range of 1 to 25 GeV is reported. Each element of the array was 20.5 radiation lengths long. The resolution of the array was measured both with and without a 3.5 radiation length SCG1-C scintillation glass active converter and 0.2 radiation length hodoscopes used to measure shower position. An energy resolution sigma/E = (1.63 + 1/46/ (RADICAL)E)% was obtained without the active converter and sigma/E = (0.64/ (RADICAL)E)% with the active converter. Performing a partial correction for the average energy loss in the 0.2 radiation length hodoscopes resulted in an energy resolution of sigma/E = (0.50 + 3.43/ (RADICAL)E)% for the active converter measurement. The measurement of the absolute number of photons produced by 1 GeV showers, the optical attenuation length for the light produced by showers, the fraction or the total light output that is due to Cerenkov light relative to scintillation light for showers, and the radiation darkening sensitivity of the scintillation glass are also reported.