  We analyze the performance of an Omnivision OV5647 CMOS image sensor (5 Mp)
for measuring the radiation emitted from Sr90 and Cs137 sources. Our
experimental arrangement includes a Raspberry Pi 3 mini-computer for data
taking, processed with Python and OpenCV libraries. We specify the camera
settings to be sensitive to detecting electrons and photons. We also implement
a detailed Geant4 simulation of the CMOS sensor and the radioactive sources.
This simulation connects the deposited energy in the pixel matrix by the
electrons and photons from the radioactive sources and the ADC counts. Our
measurements are expressed through the cluster size, the maximum ADC signal per
cluster, and the variation of the clusters with different distances. We find a
good agreement between the data and the Geant4 simulation for all these
observables. Furthermore, we can reproduce the correlation between the cluster
size and the maximum ADC per cluster.
