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Researchers have successfully tested a specialized cryogenic microchip (CRYO ASIC) designed to detect particle interactions in the nEXO experiment, which searches for a rare nuclear decay process in liquid xenon. The chip demonstrated stable operation at extremely cold temperatures (-100°C), maintaining gain stability better than 0.2% over 24 hours and achieving noise levels that meet the experimental requirements of 150 electrons. Testing confirmed that operating pressure above 0.1 MPa prevents boiling issues caused by the chip's heat output in liquid xenon.
Why it matters
This validation establishes a practical solution for reading out charge signals in next-generation particle physics detectors that must operate in cryogenic liquids. The successful integration of electronics directly into liquid xenon could enable more sensitive searches for neutrinoless double beta decay, a process that could reveal fundamental properties of neutrinos and matter-antimatter asymmetry in the universe.
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⚠️ Preprint – Noch nicht peer-reviewed
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Abstract: nEXO is a proposed next-generation experiment searching for the neutrinoless double beta decay of $^{136}$Xe using a tonne-scale liquid xenon (LXe) time projection chamber (TPC). To image the ionization signals from events in the liquid xenon, the detector will employ metallized fused-silica charge collection tiles instrumented with cryogenic application-specific integrated circuits (ASICs), referred to as CRYO ASIC, which are designed to operate directly in LXe to minimize input capacitance and pick-up noise. Here we present the performance of the CRYO ASIC mounted on an auxiliary printed circuit board and evaluated both in a cryogenic environmental chamber and in a dedicated LXe test stand. We demonstrate that the ASICs achieve the desired performance at liquid xenon temperatures, showing a gain stability better than 0.2% over 24-hour operation and reliable in-situ calibration using an on-chip pulser. In the LXe test stand, we show that boiling caused by the chip heat dissipation can be mitigated by operating the system above ~0.1 MPa. The in-LXe noise measured agrees with simulation, which indicates it the $150~e^-$ design requirement can be satisfied. These results establish CRYO ASIC as a viable low-noise in-LXe charge readout solution for nEXO.
Source: Characterization of CRYO ASIC for charge readout in the nEXO experiment