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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Lifetimes of states in the ground-state bands of (70)Se and (72)Se were measured using the recoil-distance Doppler shift method. The results deviate significantly from earlier measurements, requiring a revision of the conclusions drawn from a recent Coulomb excitation experiment concerning the shape of (70)Se. The new results lead to a coherent picture of shape coexistence in the neutron-deficient selenium and krypton isotopes. The coexistence and evolution of oblate and prolate shapes in this mass region is for the first time consistently described by new Hartree-Fock-Bogolyubov-based configuration-mixing calculations which were performed using the Gogny D1S interaction.

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Multinucleon transfer reactions in 40Ca+96Zr and 90Zr+208Pb have been measured at energies close to the Coulomb barrier in a high-resolution γ-particle coincidence experiment. The large-solid-angle magnetic spectrometer PRISMA coupled to the CLARA γ array has been employed. Trajectory reconstruction has been applied for the complete identification of transfer products. Mass and charge yields, total kinetic energy losses, γ transitions of the binary reaction partners, and comparison of data with semiclassical calculations are reported. Specific transitions in 95Zr populated in one-particle transfer channels are discussed in terms of particle-phonon couplings. The γ decays from states in 42Ca in the excitation energy region expected from pairing vibrations are also observed

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High-spin states in138 Nd were investigated using the reaction 94 Zr( 48 Ca,4n), detecting coincident γ-rays with the gasp spectrometer. A rich level scheme was constructed including 4 bands of negative parity at low spins, 8 bands of dipole transitions and 8 bands of quadrupole transitions at medium spins. The Cranked Shell Model and the Tilted Axis Cranking model are used to assign configurations to the observed bands, where zero pairing is assumed. For selected configurations the case of finite pairing is also considered. A consistent notation for configuration assignment is introduced, which applies both for zero and finite pairing. The observed bands are interpreted as rotation around the short and long principal axes (quadrupole bands), as well as around a tilted axis (dipole bands). The dipole bands have an intermediate character, between magnetic and collective electric rotation. A pair of dipole bands are candidates for chiral partners, the first case this property has been identified in an even-even nucleus. The possible existence of the wobbling mode at low deformation and medium spins is discussed. The consistent interpretation of the multitude of observed bands strongly supports the existence of stable triaxial deformation at medium spins in 138 Nd.

Multinucleon transfer cross sections in the 96 Zr+ 40 Ca system have been measured, in inverse kinematics, at bombarding energies ranging from the Coulomb barrier to ∼25% below. Targetlike recoils have been identified in A, Z and velocity with the large solid angle magnetic spectrometer PRISMA. The experimental data for oneand two-neutron transfer channels have been compared with semiclassical microscopic calculations. For the two-neutron transfer channels the relevance of the transitions to the ground state and to the 0 + excited states of 42 Ca are discussed by employing, for the reaction mechanism, the successive approximation. It is found that the transition to the 0 + state at ∼6 MeV, whose wave function is dominated by the two neutrons in the 2p 3/2 shell, is much larger than the ground state one. The comparison with the inclusive data reveals that transitions to states with high multipolarity and non-natural parity are important. This suggests that more complex two-particle correlations have to be incorporated in the treatment of the transfer process.