WA80 BGO calorimetry electronics

The authors describe instrumentation designed for BGO scintillator-based calorimetry of particles covering a very wide range of energies (from less than 50 MeV to 50 GeV). The instrumentation was designed to have a measurement accuracy of 0.1% over as much of the energy range as possible so that the energy resolution of BGO would be the limiting factor. Two 1.5-cm/sup 2/ photodiodes were used per 2.5-cm*2.5-cm*25-cm BGO crystal. Both a charge-sensitive preamplifier and a pulse processor were developed specifically for the needs of the WA80 experiment. The preamplifier was designed for high detector capacitance (100 to 700 pF), low integral and differential nonlinearity, and low power consumption (200 mW). The pulse processor is a time-invariant shaping amplifier with integral peak-detect-and-hold and automatic gain selection circuits. The amplifier uses quasi-triangular shaping with 4- mu s peaking time, and the hold circuit is gated with a fast level trigger. The system has more than 20 b of effective resolution when used with an external 12-b ADC (analog-to-digital converter). Preliminary results from beam tests at CERN are presented.<>