An overview of the MASCO balloon-borne gamma-ray experiment Original Research Article

We present a detailed description of the technical characteristics of the MASCO balloon-borne gamma-ray experiment, which is an instrument designed to obtain images of cosmic sources with a 14-arcminute resolution over an ∼ 14-degree circular field of view. It operates between 50 keV and 1.8 MeV. The MASCO experiment employs a Modified Uniformly Redundant Array coded mask and a NaI(Tl) position sensitive detector. The attitude control system was designed to provide a few arcminutes pointing and stabilization for a ∼ 2,000 kg, 7-m high, 2-m wide, 2-m deep gondola that encompasses the telescope and its associated electronics. We describe the imaging system, the attitude control system, and the gondola where the telescope is mounted on. We also show some results of new tests performed with the instrument: the 1-σ detector spatial resolution in the X-axis is 1.04 cm and 1.14 cm in the Y-axis for an Am241 source; for a Na22 source, the spatial resolution in the X-axis is 1.67 cm and 1.39 cm in the Y-axis; the attitude control system tests showed that the instrument is able to maintain a target locked with at least 5-arcminute accuracy.