Real-Time Readout System Design for the BULLKID-DM Experiment: Enhancing Dark Matter Search Capabilities

The BULLKID-DM experiment aims to detect WIMP-like potential Dark Matter particles with masses below 1 GeV/c<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula>. Sensing these particles is challenging, as it requires nuclear recoil detectors characterized by high exposure and an energy threshold in the order of 100 eV, achieved with cryogenic phonon detectors. BULLKID-DM introduces a detector that combines the low energy threshold with a new scalable technology, reaching a total target mass of 800 g. The core detector of the BULLKID-DM experiment is composed of 16 100mm silicon wafers, each segmented in 145 dice for a total of more than 2000 units, each sensed by a Microwave Kinetic Inductance Detector (MKID). The MKIDs on each wafer are coupled to a single transmission line and read using a frequency division multiplexing approach by the room-temperature data acquisition. In this contribution, we describe and assess the design of the room-temperature readout electronics system, including the selected hardware components and the FPGA firmware which contains the real-time signal processing stages for tone generation, frequency demultiplexing, and event triggering. We evaluate the system on the ZCU216 board, a commercial evaluation card built around a Radio-Frequency System-on-Chip (RFSoC) with integrated high-speed DACs and ADCs, and connected it to a custom-designed analog front-end for signal conditioning.