Development of the Front-End Electronics for PandaX-III Prototype TPC

The particle and astrophysical xenon experiment III (PandaX-III) is aimed to search for the Neutrinoless Double Beta Decay (NLDBD) using 200-kg radio-pure high-pressure gaseous xenon time projection chamber (TPC) with Micromegas detectors at both ends. A small-scale prototype TPC equipped with seven Microbulk Micromegas modules has been developed. Each Micromegas module has 128 anode strip signals to be processed. Highly integrated front-end electronics composed of four front-end cards (FECs) with 1024 channels are designed to read out the charge of Micromegas anode signals digitize the waveform after shaping and send compressed data to the data collection module (DCM). The cornerstone of the front-end electronics is a 64-channel application-specific integrated circuit (ASIC) named AGET, which is based on switched capacitor arrays (SCAs). According to the test results, the integral nonlinearity (INL) of the front-end electronics is less than 1%, and the noise of each readout channel with the input floating is less than 0.9 fC on the condition of 1- $\mu \text{s}$ peaking time and 1-pC dynamic range. Joint tests of front-end electronics with the prototype TPC were carried out using the radioactive sources 137Cs and 241Am. The hit map of the Micromegas modules and the energy spectrum have been reconstructed successfully, and the results are satisfying.