The present work deals with a scintillation detector made of a LuYAP:Ce array coupled to a position-sensitive photo-multiplier tube, whose structure is well suitable for SPECT and PET, but also in nuclear physics, astrophysics, astroparticle physics, homeland security, and non-proliferation. The response was investigated under Co-57, Ba-133, Cs-137 gamma-ray irradiation, and with Lu-176 self-activity. The investigation, based on the 2-D charge-profiles spread, provides means for identifying and rejecting multiple-interactions in the crystal-array, like Lu X-ray escape photons, and Compton-scattered ones. [ABSTRACT FROM AUTHOR]