... Main research and development work completed in 2011 and ready for implementation . ... It is found that the 1.8 MeV line is concentrated in the Galactic disk, whereas positron annihilation takes place in the central region of the Galaxy. ... Main research and development work completed in 2010 and ready for implementation . Main research and development work completed in 2009 and ready for implementation . Main research and development work completed in 2008 and ready for implementation ...