Gamma-ray tracking for large detector arrays

New accelerator facilities for radioactive-ion beams will enter into operation in the next five years, providing the opportunity to explore unknown territories of the nuclear landscape. The foreseen harsh experimental conditions requires the construction of a new type of detector arrays for high precision γ-ray spectroscopy, based on the emerging technique of γ-ray tracking. AGATA in Europe and GRETA in the US will be built out of 120/180 highly segmented germanium crystals operated in position sensitive mode by means of digital data techniques and pulse shape analysis of the segment signals. These arrays are capable of measuring gamma radiation in a large energy range (from ∼10 keV to ∼10 MeV), with the largest possible photopeak efficiency (25% at M_γ=30) and with good spectral response. The very good Doppler correction and background rejection capability of this detector allows to perform γ-ray spectroscopy experiments using fragmentation beams with sources moving at velocities up to β ∼0.5.