Charge Sensitive Amplifier (CSA) in cold gas of Liquid Argon (LAr) Time Projection Chamber (TPC)

This paper presents our work on a 8-channel low noise Front-End electronic coupled to a Liquid Argon (LAr) TPC (Time Projection Chamber). Each channel consists of a Charge Sensitive Amplifier (CSA), a band pass filter and a 50 Ohms buffer as line driver. A serial link based on a `i2c-like´ protocol, provides multiple configuration features to the circuit by accessing slow control registers. Only the CSA part is described in this paper. The feedback network of the CSA is made of a capacitance and a resistor. Their values are respectively 250 fF and 4 MΩ. An input referred noise of, at most, 1500 e-rms must be achieved at -100°C with an input detector capacitance of 250 pF to ensure a correct measurement of the minimal signal of 18000e-(2.88 fC). The power consumption in this cryogenic setup must be less than 40 mW from a 3.3 V power supply.