  For the first time, a small dual-phase (liquid/gas) xenon time projection
chamber was equipped with a top array of silicon photomultipliers for light and
charge readout. Here we describe the instrument in detail, as well as the data
processing and the event position reconstruction algorithms. We obtain a
spatial resolution of ~1.5 mm in the horizontal plane. To characterise the
detector performance, we show calibration data with internal $^{83\text{m}}$Kr
and $^{37}$Ar sources, and we detail the production of the latter as well as
its introduction into the system. We finally compare the observed light and
charge yields down to electronic recoil energies of 2.82 keV to predictions
based on NEST v2.0.
