  In recent years the number of CubeSats (U-class spacecrafts) launched into
space has increased exponentially marking the dawn of the nanosatellite
technology. In general these satellites have a much smaller mass budget
compared to conventional scientific satellites which limits shielding of
scientific instruments against direct and indirect radiation in space. In this
paper we present a simulation framework to quantify the signal in large
field-of-view gamma-ray scintillation detectors of satellites induced by
X-ray/gamma-ray transients, by taking into account the response of the
detector. Furthermore, we quantify the signal induced by X-ray and particle
background sources at a Low-Earth Orbit outside South Atlantic Anomaly and
polar regions. Finally, we calculate the signal-to-noise ratio taking into
account different energy threshold levels. Our simulation can be used to
optimize material composition and predict detectability of various
astrophysical sources by CubeSats. We apply the developed simulation to a
satellite belonging to a planned CAMELOT CubeSat constellation. This project
mainly aims to detect short and long gamma-ray bursts (GRBs) and as a secondary
science objective, to detect soft gamma-ray repeaters (SGRs) and terrestrial
gamma-ray flashes (TGFs). The simulation includes a detailed computer-aided
design (CAD) model of the satellite to take into account the interaction of
particles with the material of the satellite as accurately as possible. Results
of our simulations predict that CubeSats can complement the large space
observatories in high-energy astrophysics for observations of GRBs, SGRs and
TGFs. For the detectors planned to be on board of the CAMELOT CubeSats the
simulations show that detections with signal-to-noise ratio of at least 9 for
median GRB and SGR fluxes are achievable.
