Title： Observing cosmic nuclei in gamma rays 
Speaker：Roland Diehl（MPE Garching, Germany） 
Moderator： Prof. Zhang Shuangnan
Time: 2:30 - 3:30, March 8
Place: Room C305, IHEP Main Building 
Abstract:
INTEGRAL's spectrometer SPI (ESA, 2002-2029) has been measuring gamma rays with high spectral resolution from sources such as radioactive decay in interstellar-gas, and annihilating positrons, and from supernova explosions, as well as supernova remnants. Specifically, in this energy band 20-8000 keV lines from 56Ni, 44Ti, 26Al, 60Fe, and the 511 keV line are observed. 
From this, we learned new aspects of nucleosynthesis throughout our galaxy and its stellar groups, about propagation of nucleosynthesis ejecta, and also of positrons. Also, new and specific insights about supernovae explosions, both of type core collapse and of type Ia, are becoming accessible in such measurements.In this talk, we will review achievements of gamma-ray spectroscopy, and discuss prospects for the next decade. 

About the speaker: 
Prof.Dr.Roland Diehl is senior staff scientist at the Max Planck Institut für extraterrestrische Physik (MPE) in Garching, Germany. His main research field is Nuclear Astrophysics, and specifically observations of cosmic nuclei using gamma-ray telescopes. Roland Diehl studied nuclear physics in Mainz, Germany, and graduated in Munich, Germany, in observational gamma ray astrophysics. Roland Diehl holds a professorship at Munich’s Technical University. He was involved in MPE’s space projects for gamma-ray astronomy, with NASA’s Compton Gamma-Ray 
Observatory CGRO (1991-2000), and with ESA’s INTEGRAL observatory (2002-today) he is Co-Principal Investigator of the SPI gamma ray spectrometer. Major scientific achievements are the studies of current nucleosynthesis and feedback from massive star groups using ^26 Al, the discovery of ^56 Ni radioactive decay from a thermonuclear supernova (type Ia), tracing the annihilation of positrons throughout the interstellar medium of our Galaxy, and in pair plasma near the event horizon of an accreting black hole.