A 32-Channel ASIC for the Readout of Pixelated Liquid Argon Time Projection Chambers

A 32-channel ASIC called LArPix, intended for instrumenting pixelated readout of Liquid Argon Time Projection Chambers (LAr-TPCs), is presented. The reduced capacitance and relaxed noise specifications of a pixelated LAr-TPC allow significant power reductions relative to a traditional wire plane-based LAr-TPC. Each channel employs largely dynamic signal processing that consumes low power when idle. To reduce the number of cryostat penetrations to a manageable level, multiple LArPix chips can be daisy chained and communicated with using two wires. LArPix, with a die area of approximately 32.8 mm
²
and fabricated in 180 nm CMOS technology, achieves 250 e-ENC at LN2 temperature while dissipating 61 μW per channel. The prototype has been used to successfully image cosmic-ray muons in a pixelated LAr-TPC.