[en] A novel 4 π γ-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 γ-ray tracking will be employed to distinguish γ-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. (author)