Abstract:
Gamma-ray astronomy in the MeV energy range is an important window for the study of stellar evolution, supernova explosion, neutron star merger, and in particular, nucleosynthesis in these systems, and also a useful probe to constrain the physics of compact objects and even planetary formation. I will introduce the science of some strong astrophysical emission lines, including the positron-electron annihilation line (0.511 MeV),neutron-capture line, and radioactive decay lines from radioisotopes such as 26Al (1.809 MeV), 44Ti (1.157 MeV), 56Co (0.847 & 1.238 MeV), and 60Fe(1.173 & 1.332 MeV). Compton imaging is so far the best practical means for MeV detection in astronomy. We propose a future mission concept, the MeV Astrophysical Spectroscopic Surveyor (MASS), a large area Compton telescope optimized for MeV emission line detection.
