A detector providing two dimensional spatial measurement of calorimeter showers is described. It consists of scintillator fingers read out by photodiodes. Results from a prototype evaluated in a test ...beam are given, including the effects of charged particle detection by the photodiodes.
Further tests of lead tungstate crystal matrices made in high-energy electron beams in 1996, using new crystals, new APDs and an improved test setup confirm that an energy resolution of better than ...0.6% at 100
GeV can be obtained when the longitudinal uniformity of the struck crystal is adequate. Light loss measurements under low dose irradiation are reported. It is shown that there is no loss of energy resolution after irradiation and it is demonstrated that the calibration change due to light loss can be tracked with a precision monitoring system. Successful tests with a preshower device, equipped with a silicon strip detector readout, are also described.
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