ИСТИНА

Despite the evident limitations on size, mass, power consumption and other board resources CubeSats give good opportunity for observations needing use of several spacecraft, so-called constellation. As example of such observations study of Terrestrial Gamma-ray Flashes (TGFs) with the use of several nano-satellites can be discussed. In the case of constellation of CubeSats placed in the orbits in such a way that mean distance between them will be about thousand kilometres the triangulation technique for TGF source location can be realized. For such observations we present advanced position–sensitive gamma detector adapted for CubeSat format This instrument should be consisted from a set of minimum 16х16 scintillating crystals of Cе:GAGG type, with size of 1.0х1.0х3.0 cm3 each, that should be placed along one CubeSat side. As it is well-known Ce:GAGG crystals have quite high light output (~57 000 phot/МeV) and density (~6.7 g/cm3) with sufficiently small decay time of ~80 ns, that ensures a high throughput of the unit. The fast crystals help to realize the high accuracy of the time measurements and high throughput of the measuring channel. Relatively high density of Ce:GAGG crystals provides the high efficiency of gamma quantum detection in wide energy range. Due to the high light output Ce:GAGG scintillators also give good energy resolution. For example, we have tried Cе:GAGG pixels with thickness of 3.0 cm, and found the high detection efficiency of gamma quanta with energies up to a several MeV, and an energy resolution of ~4% at 1 МeV. The Si-PM light sensors, or small vacuum photomultipliers could be used for viewing of Cе:GAGG crystals. For example, Hamamatsu R1463 is quite compact photomultiplier with an input window of Ø13 mm. R1463 photo cathode is sensitive at the wavelengths of 300 – 650 nm, with maximum cathode sensitivity at about 420 nm, that is in good correspondence with the emission spectrum of Ce:GАGG.   The tracking gamma spectrometer has its own read-out unit of analogous and digital electronics.