Construction and Response of a Highly Granular Scintillator-based Electromagnetic Calorimeter

A highly granular electromagnetic calorimeter with scintillator strip readout is being developed for future lepton collider experiments. A prototype of 21.5 $X_0$ depth and $180\times 180$mm${}^2$ transverse dimensions was constructed, consisting of 2160 individually read out $10\times 45\times 3$ mm${}^3$ scintillator strips. This prototype was tested using electrons of 2–32 GeV at the Fermilab Test Beam Facility in 2009. Deviations from linear energy response were less than 1.1%, and the intrinsic energy resolution was determined to be $(12.5 \pm 0.1 ($\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.}$) \pm0.4 ($\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.}$))%/\sqrt{E[$\mathrm{G}\mathrm{e}\mathrm{V}$]}\oplus (1.2 \pm 0.1($\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.}$)^{+0.6}_{-0.7}($\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.}$))%$, where the uncertainties correspond to statistical and systematic sources, respectively.