0720028

One of the key investigations so far performed by the INTEGRAL Observatory after six years of operation has been the soft gamma-ray GCDE and the GPS successfully exploited to a depth of better than 1 mCrab in the central region with unprecedented details due to the >20 Ms exposure on 5x5 squared degree centred on SGR A*. More recently the new INTEGRAL view of the extragalactic soft gamma-ray sky has been complemented by the excellent sky coverage provided by the SWIFT/BAT extragalactic survey overlapping the IBIS one in lower energy range (E<200 keV). SWIFT has now achieved a deeper average sensitivity for the extragalactic survey while INTEGRAL has a almost a factor of 10 better sensitivity over the Galaxy plane due to the 5Ms average exposure. This true for the whole plane but for two important regions that are only covered at a level of 1Ms and 2 Ms respectively: the two regions are basically coincident with the outer Perseus spiral arms. In those regions the material is considerably less dense and we will be able to extend our present studies of compact objects through a detailed comparison of the relative populations of all classes of gamma-ray emitting galactic types in the very different environment provided in these outer regions. A more complete understanding of our high energy galaxy will be the result. Finally last but not least this is a unique opportunity to obtain a deep so ft gamma ray coverage of the Galaxy plane: an invaluable INTEGRAL Legacy for futurfture high energy studies.This proposal is specifically designed to reach this goal thus making a corner stone in the high energy understanding of our Galaxy behaviour in the 17-600 keV range and provide a text book for future soft gamma-ray population studies and focus future gamma-ray missions scientific objectives as per Simbol-X EXIST and ultimately IXO. [truncated! Please see actual data for full text]