The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation γ-ray spectrometer. AGATA is based on the technique of γ-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a γ ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of γ-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterisation of the crystals was measured and compared with detector-response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximise its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer

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Excited levels in 69 Se have been studied using the 40 Ca͑ 32 S,2pn͒ 69 Se reaction at 95-and 105-MeV beam energy. ␥ rays have been detected with the EUROBALL spectrometer operated in conjunction with the neutron wall and the charged-particle detector array EUCLIDES. New level sequences with positive and negative parities have been identified from n-␥␥ and n-␥␥␥ coincidences. Spins have been assigned to many of the levels on the basis of angular distribution and directional correlation measurements. Excitation energies of the positive-parity yrast band and the branching ratios of its decay are compared with the predictions of the rigid triaxial rotor plus particle model.

The neutron-deficient nucleus 66 Ge was populated at high spin in two experiments using the reaction 40 Ca(32 S,␣2p) at beam energies of 105 and 95 MeV. In the first experiment, a self-supporting 40 Ca target was used, while a gold-backed target of similar thickness was used in the second experiment. ␥ rays were detected with the EUROBALL array, combined with the charged-particle detector array EUCLIDES and the Neutron Wall. The level scheme of 66 Ge was extended up to EϷ18 MeV and I ϭ(23 Ϫ). Above angular momentum 10 ϩ , we found two sequences, connected by energetically staggered ⌬Iϭ1 M 1 transitions. The total Routhian surface calculations describe 66 Ge at lower spins as a ␥-soft nucleus having a moderate deformation of ␤ 2 Ϸ0.23, while a triaxial deformation is predicted for the band structures above I ϭ10 ϩ. To our knowledge, this is the first observation of staggered M 1 transitions in a deformed four-quasiparticle (g 9/2 2)(g 9/2 2) structure.