CERN Accelerating science

Université de Genève : Gamma-ray lines astronomy

Ecole de physique
Département de physique nucléaire et corspusculaire

24, Quai Ernest-Ansermet
1211 Genève 4
Tél. : (022) 379 62 73
Fax: (022) 379 69 92

Gamma-ray lines from cosmic sources provide unique isotopic information, since they originate from energy level transitions in the atomic nucleus. Gamma-ray telescopes explored this astronomical window in the past three decades, detecting radioactive isotopes that have been ejected in interstellar space by cosmic nucleosynthesis events. Astronomical gamma-ray telescopes feature standard detectors of nuclear physics, but have to be surrounded by effective shields against local instrumental background, and need special detector and/or mask arrangements to collect imaging information. Due to exceptionally-low signal/noise ratios, progress in the field has been slow compared with other wavelengths. Despite the difficulties, this young field of astronomy is well established now, in particular due to advances made by NASA's Compton Gamma-Ray Observatory in the 90ies. The most important achievements on extra-solar gamma-ray lines so far concern: short-lived radioactivities that have been detected in a couple of supernovae (56Co and 57Co in SN1987A, 44Ti in Cas-A), the diffuse glow of long-lived 26Al and 60Fe that that has been mapped along the entire plane of the Galaxy, and last but not least, positron annihilation that has been observed in the inner Galaxy since the 70ies. I will review past and future developments in the field, in the light of recent results from ESA's INTEGRAL satellite, which is in operation since early 2003.

Information : http://dpnc.unige.ch/seminaire/annonce.html
Organizer : J.-S. Graulich