BeamCal Instrumentation IC: Design, Implementation, and Test Results

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 beamstrahlung electron-positron 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 the integrated circuit under study to fulfill these requirements. To process the signal charge at the International Collider pulse rate, the Bean uses switched-capacitor filters and a slow reset-release technique. Each channel has a 10-bit successive approximation analog-to-digital converter. The Bean also features a fast feedback adder capable of providing a low latency output for beam diagnostic purposes. This work presents the design and characterization of a 3-channel prototype of the Bean built to validate concepts while the final device will comprise 32 channels.