PERFORMANCE OF A LONGITUDINALLY-SEGMENTED CSI(TL) ARRAY SUITABLE FOR A DETECTOR IN A LOW OR MEDIUM-ENERGY E(+)E(-) STORAGE-RING

We present results on energy resolution and linearity, and position resolution, from a test of an array of CsI(Tl) crystals in a pi/e/mu beam (120 to 400 MeV) at TRIUMF. The crystal array was designed to study the effects of longitudinal and transverse crystal segmentation on energy and position resolution and background rejection. We also studied the feasibility of a wavelength-shifter and multi-photodiode readout system, suitable for use in magnetic detectors at low and medium energy, high-luminosity e+e- storage rings. Energy resolutions of (1.69 +/- 0.08)%/square-root E(GeV) and (1.83 +/- 0.05)%/square-root E(GeV) were obtained for two different crystal tower configurations. Position resolution of 6.5 (9.0) mm was obtained at 300 (120) MeV for a 2 x 2 square array of four 4 x 4 x 7.4 cm3 crystals transverse to the beam.