Annihilation puzzles for INTEGRAL

The instrument is operational, the analysis team assembled and the observations have begun. As we are on the precipice of the INTEGRAL era of annihilation radiation science, it is timely to review the findings of the CGRO/OSSE instrument by posing four new puzzles for the INTEGRAL satellite's SPI and IBIS teams. The puzzles are: (1) Is there a Galactic Center point source? (2) What is the Bulge-Disk ratio? (3) Does the annihilation fountain exist? (4) Is there Gould Belt emission? Answering these four puzzles will not be easy and will likely require dedicated observations beyond those scheduled as part of the Core Program . However, if all four can be definitively answered, annihilation radiation science will have moved very close to being able to account for the production of galactic positrons and will be ready to use positron annihilation to probe the Galaxy.