  This article reports the first operation of a double-sided CMOS pixelated
ladder in a collider experiment, namely in the inner tracker volume of the
Belle II experiment during the Phase 2 run of the SuperKEKB collider. Design
and integration of the detector system in the experiment interaction region is
first described. The two modules operated almost continuously during slightly
more than four months, recording data for the monitoring of the hit rate close
to beams. Details of the off-line data analysis are provided and a method to
estimate particle momentum from the 2 hits measured per crossing particle is
proposed.
