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

The Particle And Astrophysical Xenon Experiment III (PandaX-III) is an experiment to search for the Neutrinoless Double Beta Decay (NLDBD) using 200 kg radio-pure high-pressure gaseous xenon TPC with Micromegas detectors at both ends and cathode in the middle. A small-scale TPC equipped with 7 Microbulk Micromegas detectors is developed as the prototype detector. 128 channels are readout following an X-Y design with strips of 3 mm pitch (64 channels each direction) from one Micromegas module. Highly integrated front-end electronics composed of 4 front-end cards with 1024 readout channels is designed to readout the charge of Micromegas anode signals, digitize the waveform after shaping and send compressed data to the DCM board. The cornerstone of the front-end electronics is a 64-channel application specific integrated circuit which is based on a switched capacitor array. The integral nonlinearity of the front-end electronics is less than 1% with 1 pC. The noise (RMS) of each readout channel is less than 0.9 fC with 1 microsecond peaking time and 1 pC range. Using the radioactive sources 56 Fe and 137 Cs, joint-tests of front-end electronics with the prototype TPC were carried out and the hit map of 7 Micromegas has been reconstructed.