A gamma-ray imaging camera for ambient radioactivity detection

The aim of this work is to design a camera for gamma-ray imaging based on the coded mask technique widely used in astrophysics. The camera proposed is a compact, lightweight instrument, ideal for real-time analysis, with a low power consumption. The proof of concept consist in 16 CsI(Tl) scintillators coupled to photo-multiplier tubes (PMTs) with a digital readout. The scintillators are arranged in a 4 x 4 matrix and packaged in a metallic frame. We used a 7 x 7 mask composed by transparent and opaque files to encode and decode a radioactive gamma-rays point source image through a reconstruction algorithm. The system was tested using gamma-ray radioactive sources placed at a fixed distance from the mask. The performance of the prototype camera in terms of energy and spatial resolution will be shown. An upgrade of this prototype will employ Silicon Photomultipliers (SiPMs) in place of the PMTs. A comparison of the two configurations will be also provided.