Particle physics experiments, like nEXO and ARGO, require a large-scale data acquisition system capable of supporting high data rates. One can expect a total data rate of approximately 400 Gb/s for ...nEXO, whereas ARGO estimates are on a scale of Pb/s. To support those experiments, which require a low-power and high-bandwidth communication (≈1 Gb/s per link), a modular Silicon-Photonics (SiP) communication module is in development to connect the front-end electronics to the data acquisition system (DAQ). This research focuses on the interface between more than 100 optical transceivers and the DAQ. To eliminate the need for custom hardware in the servers of the DAQ, the system is compatible with a standard Ethernet network. Targetting an Ethernet interface allows the use of commodity off-the-shelf equipment to connect custom electronics to the DAQ and simplifies integration, deployment, and maintenance. This system is composed of a Zynq system-on-chip (SoC), where the FPGA receives data from a set of transceivers and wraps the frame received in UDP datagrams sent to the DAQ; the processor handles various configurations and commands. To match the requirements on data rates and modularity, this study proposes a proof of concept demonstrating a 100 Gb/s link using a FPGA to transfer the data from the custom SiP transceivers to a server running DAQ software, implemented using the MIDAS framework. Following this work, the implemented Ethernet link will constitute a system ready to integrate with the SiP communication module. This integration will provide a platform to deploy large-scale and high data-rate DAQs for the targeted experiments, namely nEXO and ARGO.
Large-scale low-background detectors are increasingly used in rare-event searches as experimental collaborations push for enhanced sensitivity. However, building such detectors, in practice, creates ...an abundance of radioassay data especially during the conceptual phase of an experiment when hundreds of materials are screened for radiopurity. A tool is needed to manage and make use of the radioassay screening data to quantitatively assess detector design options. We have developed a Materials Database Application for the nEXO experiment to serve this purpose. This paper describes this database, explains how it functions, and discusses how it streamlines the design of the experiment.
Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0\(\nu \beta \beta\)), due to their response uniformity, monolithic sensitive volume, ...scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0\(\nu \beta \beta\) of \ce{^{136}Xe} with projected half-life sensitivity of \(1.35\times 10^{28}\)~yr. To reach this sensitivity, the design goal for nEXO is \(\leq\)1\% energy resolution at the decay \(Q\)-value (\(2458.07\pm 0.31\)~keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163~K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decay \(Q\)-value for the nEXO design.
