Speakers
Description
The upcoming ProtoDUNE-II program at the CERN neutrino platform will consist of 2 liquid argon time projection chambers, which will serve as demonstrators of the technologies that will be used in the first 2 far detectors of the Deep Underground Neutrino Experiment (DUNE). A core component of these detectors is the cryogenic charge readout electronics, which are immersed in liquid argon along with the detectors and are responsible for reading out charge signals from the anodes of the time projection chamber. This talk will discuss the design of these electronics and preliminary performance results from the ProtoDUNE-II assembly experience.
Summary (500 words)
The DUNE far detectors require readout of several hundred thousand charge-sensing channels immersed in the largest liquid argon time projection chambers ever built, calling for cryogenic front-end electronics in order to be able to adequately instrument the full detector. These electronics must satisfy power constraints of < 50 mW per channel to minimize the thermal load on the cryogenic system, be designed with lifetimes of 20+ years to remain functional throughout the expected lifetime of DUNE, and be able to reliably communicate with warm interface electronics on the other side of cold cables that are up to 30 meters long.
The cryogenic front-end electronics that will be used for charge readout of the first far detector and the bottom half of the second far detector of DUNE satisfy these requirements with a front-end motherboard (FEMB) containing a chain of 3 different ASICs: LArASIC for analog charge amplification, ColdADC for digitization into 14-bit signals, and COLDATA for multiplexing, serialization, and digital control. Each FEMB operates in liquid argon, placed directly on the detector module and reading out 128 channels with a combination of 8 LArASIC, 8 ColdADC, and 2 COLDATA. The ProtoDUNE-II experiments contain FEMBs with the final designs of each of these ASICs and will serve as the final large-scale testbeds for their performance in a DUNE-style detector collecting physics data, including the same electronics grounding scheme that will be used in DUNE and including full integration testing with the other DUNE detector components.
Although the ProtoDUNE-II experiments have not yet begun operation, the cold ASICs have undergone individual quality control tests prior to installation on the detectors, and the fully assembled constituent detector modules have been individually tested in coldbox setups at the CERN neutrino platform prior to installation in their final positions in the ProtoDUNE-II cryostats. The results of these tests are being used to refine the testing procedures that will be used for the electronics prior to their installation on the DUNE detector modules, and for the assembled DUNE detector modules prior to their installation in the DUNE far detectors. Over the course of these tests we have ascertained a > 99% good yield in manufactured ASICs and a < 0.1% loss of electronics channels after installation on the detector modules. We have also measured pedestal RMS noise levels of < 500 electrons equivalent noise charge (ENC) on collection channels and < 600 electrons ENC on induction channels while the detector is under cryogenic operating conditions, far surpassing the < 1000 electrons ENC pedestal noise required by DUNE.
