  The ATLASpix high-voltage monolithic active pixel sensor (HV-MAPS) was
designed as a technology demonstrator for the ATLAS ITk Upgrade and the CLIC
tracking detector. In this contribution new results from laboratory-based
energy calibration measurements using fluorescence X-rays are presented for the
ATLASpix Simple matrix. These findings are complemented by new results from
test-beam studies with inclined tracks, in which the active charge collection
depth is determined.
