BeamCal Instrumentation ASIC: Design, Implementation and Test Results

Abstract

The BeamCal detector, one of the calorimeters in the forward region of the International Linear Collider detector, will serve three purposes: ensure hermeticity of the detector for small polar angles, reduce the backscattering from pairs into the detector center, and provide a low-latency signal for beam diagnostics. The BeamCal specifications in terms of noise suppression, signal charge, pulse rate and occupancy pose unique challenges in the front-end and readout electronics design. The Bean – BeamCal Instrumentation IC – is a 32-channel front-end and readout IC that will address the BeamCal instrumentation requirements. By employing switched-capacitor filters and a slow reset-release technique, the Bean will process the signal charge at the International Linear Collider pulse rate. Each channel will have a 10-bit successive approximation analog-to-digital converter and digital memory for readout purposes. The Bean will also feature a fast feedback adder, capable of providing an 8-bit, low-latency output for beam diagnostic purposes. This work presents the design and characterization of the Bean prototype, a 3-channel IC that proves the principle of operation described.