A novel 4\pi \gamma -detector array designed as a closed shell of Ge crystals is currently under development. It will consist of 180 large Ge crystals. For the first time pulse shape analysis and \gamma -ray tracking will be employed to distinguish \gamma -rays scattering inside the shell and to determine the point of impact. A full energy peak efficiency of 50% at multiplicity M=1 and up to 24% at M=30 are expected, resulting in a sensitivity increase of up to three orders of magnitude for subtle nuclear structure investigations.

PACS numbers: 29.30.--h, 29.30.Kv, 29.40.Gx, 29.40.Wk