Preliminary characterization of the 64-channel MIZAR ASIC for Cherenkov light detection

This work presents the implementation and the preliminary tests of the Multi-channel Integrated Zone-sampling Analogue-memory based Readout (MIZAR) ASIC. Developed using commercial 65 nm CMOS technology, the MIZAR ASIC is designed as part of the Cherenkov camera for the POEMMA Balloon with Radio (PBR) mission. The goal of the Cherenkov camera is to detect direct Cherenkov signals produced by Extensive Air Showers (EASs) pointing towards the detector. The broader objective of the PBR mission is the detection of Ultra-High Energy Cosmic Rays (UHECRs) and tau-induced air showers resulting from the interaction of Cosmic Neutrinos with the Earth's crust. In the MIZAR ASIC, a single channel is segmented into 256 acquisition cells and each one includes a capacitor, a Wilkinson Analog-to-Digital Converter (ADC) and a digital memory. This full waveform sampling system operates with an integration time of 5 ns and the data are converted on chip at the same frequency. MIZAR is designed to send out a 64-bit hitmap to use as first-level trigger to recognize patterns of interest. Each channel can be programmed to reduce the sampling window to 32 or 64 cells and the resolution can be set within the interval 8-12 bits. MIZAR was delivered in March 2025 and it has undergone laboratory testing in recent months.