Advanced Telescope for High Energy Nuclear Astrophysics Athena

We present a space mission concept for a low energy gamma-ray telescope, ATHENA, which is under investigation as the next major advance in gamma-ray spectroscopy following the current COMPTON Gamma Ray Observatory and the planned INTEGRAL missions. The instrument c o v ers the nuclear line emission energy domain with dramatically improved sensitivity and spectral resolution. The baseline connguration combines a high resolution Compton telescope constructed from Ge planar strip detectors for the 0:3 , 10 MeV energy region with a coded-aperture system for the 10 , 200 keV domain. The Ge Compton telescope provides a broad eld of view with exceptional spectral and imaging resolution. The requirements, capabilities and simulations of ATHENA are discussed.