The Advanced Gamma Ray Tracking Array AGATA, D. Bazzacco, on behalf of the AGATA Collaboration, INFN Sezione di Padova, Italy − After a decade of development, the first detection systems based on the principle of γ−ray tracking have recently started operating in real experiments. Tracking of gamma rays is based on the capability of determining both energy and position of the individual interactions by which gamma rays are absorbed inside the large-volume germanium crystals used in gamma ray spectroscopy. If these quantities are known with sufficient precision, the gamma rays of the detected event can be reconstructed (tracked) and characterized in details. The required position sensitivity inside the germanium crystals is achieved by the combination of: a) electrical segmentation of the outer electrode, b) fully-digital data collection techniques and c) detailed analysis of the signals induced on the segments by the charge collection process. The development of this technology has been pushed by the AGATA and GRETA projects, both aiming at the ultimate 4π germanium-only detector.
The "Advanced GAmma Tracking Array" AGATA is a device of up to 180 36-fold segmented high-purity large-volume germanium crystals, which is being developed by a collaboration of 13 European countries as the main instrument for Nuclear Structure studies at the next generation of radioactive-ion and high-intensity stable beam facilities. AGATA can measure gamma radiation in a large energy range (from ~10 keV to >20 MeV), with a good spectral response and, in its full implementation, the largest possible photopeak efficiency (~50 % at Mγ = 1 and ~25 % at Mγ = 30). In particular, the very good Doppler correction and background rejection capabilities allow to perform experiments using fragmentation beams and recoils moving at velocities up to β ~ 0.5. The talk will focus on the relevant aspects of development and implementation of the first phase of AGATA, namely the AGATA Demonstrator, which has been operated at LNL during the last two years in combination with the magnetic spectrometer PRISMA and a series of other ancillary devices. At the beginning of 2012 the system has been moved to GSI to be upgraded for an experimental campaign with high recoil velocity fragmentation beams in combination to the FRS spectrometer.