0520071

This proposal is a continuation of the on-going (AO4) program of making a several Msec long series of multiple latitude scans of selected regions of the Galactic disk. This technique of studying the extended high-energy emission of the Galaxy has proved to be very successful in minimizing systematic errors associated with the SPI and ISGRI detectors background variations and thus providing a clean emission spectrum of the Galactic disk limited only by the photon counting statistics. In this proposal a region of the Galactic disk outside the central bulge at l~40 is selected. The ultimate goal of the entire project is to have model independent and systematics free measurements of the fluxes in nuclear lines and a broad band spectrum of the Galactic background emission. The proposed scanning technique is at present the only proven way to achieve these goals without hitting the systematics limit. Comparison of these data with the existing deep observations of the central Galactic bulge and the inner part of the Galactic disk (AO4) will allow one to address the most fundamental questions facing INTEGRAL: i) clarify the role of stellar nucleosynthesis in the production of positrons ii) place tight constraints on the fate of the positrons iii) allow a detailed comparison between the A26 and Fe60 nuclear lines emission and the star formation rate in different parts of the Galactic disk iv) provide the most accurate measurement of the Galactic hard X-ray and gamma ray diffuse emission and measure or put an upper limit on the population of low energy cosmic rays in the Galaxy which cannot be measured my other means. Taking into account the unique combination of properties of INTEGRAL instruments the proposed strategy is the best possible usage of the INTEGRAL time. Proposed observations will provide results on the high energy properties of the Milky Way that will not be overcome for decades and will therefore build up [truncated! Please see actual data for full text]