Front-end readout electronics design for the anti-coincidence detector and charge detector in VLAST

Abstract

Building on experience gained from the DArk Matter Particle Explorer (DAMPE) mission, a new satellite mission-the Very Large Area gamma-ray Space Telescope (VLAST) is proposed to advance $\gamma$-ray observations and extend cosmic-ray nucleus measurements to zirconium (Zr, Z = 40) or heavier ions. As key subdetectors of VLAST, the charge detector requires a wide dynamic range to measure cosmic-ray particles from protons to ultra-heavy ions, while the anti-coincidence detector must exhibit high detection efficiency. This paper presents the prototype design of an electronic readout system applicable to both detectors. Charge information is derived via high-precision measurement using the IDE3381 ASIC, featuring amplification, shaping, and trigger signal functions. Data from waveform digitization are processed by the Data Acquisition (DAQ) board and categorized into scientific data and trigger signals, and transmitted to the host PC and trigger logic unit. Preliminary tests indicate the system has noise levels below 28 fC, a dynamic range of 100 fC to 40 pC, and can handle event rates of $<$370 kHz. With the assistance of the electronic system, the Anti-Coincidence Detector (ACD) tile achieves a detection efficiency of 99.9% for a threshold of 0.3 Minimum Ionizing Particles (MIPs) and the charge detector (CD) are capable of performing measurements and identification of ultra-heavy ions.