  High-energy phenomena in the cosmos, and in particular processes leading to
the emission of gamma- rays in the energy range 10 MeV - 100 GeV, play a very
special role in the understanding of our Universe. This energy range is indeed
associated with non-thermal phenomena and challenging particle acceleration
processes. The technology involved in detecting gamma-rays is challenging and
drives our ability to develop improved instruments for a large variety of
applications. GAMMA-LIGHT is a Small Mission which aims at an unprecedented
advance of our knowledge in many sectors of astrophysical and Earth studies
research. The Mission will open a new observational window in the low-energy
gamma-ray range 10-50 MeV, and is configured to make substantial advances
compared with the previous and current gamma-ray experiments (AGILE and Fermi).
The improvement is based on an exquisite angular resolution achieved by
GAMMA-LIGHT using state-of-the-art Silicon technology with innovative data
acquisition. GAMMA-LIGHT will address all astrophysics issues left open by the
current generation of instruments. In particular, the breakthrough angular
resolution in the energy range 100 MeV - 1 GeV is crucial to resolve patchy and
complex features of diffuse sources in the Galaxy as well as increasing the
point source sensitivity. This proposal addresses scientific topics of great
interest to the community, with particular emphasis on multifrequency
correlation studies involving radio, optical, IR, X-ray, soft gamma-ray and TeV
emission. At the end of this decade several new observatories will be
operational including LOFAR, SKA, ALMA, HAWK, CTA. GAMMA-LIGHT will "fill the
vacuum" in the 10 MeV-10 GeV band, and will provide invaluable data for the
understanding of cosmic and terrestrial high-energy sources.
