The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation gamma-ray spectrometer. AGATA is based on the technique of gamma-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 gamma 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 gamma-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. (C) 2011 Elsevier B.V. All rights reserved.AGATA and this work is supported by the European funding bodies and the EU Contract RII3-CT-2004-506065, the German BMBF under Grants 06K-167 and 06KY205I, the Swedish Research Council and the Knut and Alice Wallenberg Foundation, UK EPSRC Engineering and Physical Sciences Research Council, UK STFC Science and Technology Facilities Council, AWE plc, Scientific and Technological Research Council of Turkey (Proj. nr. 106T055) and Ankara University (BAP Proj. nr. 05B4240002), the Polish Ministry of Science and Higher Education under Grant DPN/N190/AGATA/2009, the Spanish MICINN under grants FPA2008-06419 and FPA2009-13377-C02-02, the Spanish Consolider-Ingenio 2010 Programme CPAN (contract number CSD2007-00042) the Generalitat Valenciana under Grant PROMETEO/2010/101, and research performed in the frame of the GSI-IN2P3 collaboration agreement number 02-42. MICINN, Spain, and INFN, Italy, through the AIC10-D-000568 bilateral action.Peer Reviewe

The superheavy element with atomic number $Z=117$ was produced as an evaporation residue in the ${}^{48}\mathrm{Ca}+{}^{249}\mathrm{Bk}$ fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their $\alpha$-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-$\mu \mathrm{s}$ and a few days. Two decay chains comprising seven $\alpha$ decays and a spontaneous fission each were identified and are assigned to the isotope ${}^{294}117$ and its decay products. A hitherto unknown $\alpha$-decay branch in ${}^{270}\mathrm{Db}$ ($Z=105$) was observed, which populated the new isotope ${}^{266}\mathrm{Lr}$ ($Z=103$). The identification of the long-lived ($T_{1/2}={1.0}_{-0.4}^{+1.9}\mathrm{h}$) $\alpha$-emitter ${}^{270}\mathrm{Db}$ marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an “island of stability.”

The fusion-evaporation reaction Pu244(Ca48,3-4n)114288,289 was studied at the new gas-filled recoil separator TASCA. Thirteen correlated decay chains were observed and assigned to the production and decay of 114288,289. At a compound nucleus excitation energy of E*=39.8\char21{}43.9\,\,MeV, the 4n evaporation channel cross section was 9.8-3.1+3.9\,\,pb. At E*=36.1\char21{}39.5\,\,MeV, that of the 3n evaporation channel was 8.0-4.5+7.4\,\,pb. In one of the 3n evaporation channel decay chains, a previously unobserved $\alpha${}~branch in Ds281 was observed (probability to be of random origin from background: 0.1%). This $\alpha${}~decay populated the new nucleus Hs277, which decayed by spontaneous fission after a lifetime of 4.5~ms.

We report the observation of neutrons released from ${d(d,n)\mathrm{}}^3\mathrm{He}$ fusion reactions in the focus of 200 mJ, 160 fs Ti:sapphire laser pulses on a deuterated polyethylene target. Optimizing the fast electron and ion generation by applying a well-defined prepulse led to an average rate of 140 neutrons per shot. Furthermore, the production of a substantial number of MeV γ rays could be observed. The occurrence of neutrons and γ rays is attributed to the formation and explosion of a relativistic plasma channel in the laser focus, which is confirmed by numerical calculations.

Experiments with the new recoil separator, Transactinide Separator and Chemistry Apparatus (TASCA), at the GSI were performed by using beams of ${}^{48}\mathrm{Ca}$ to irradiate targets of ${}^{206-208}\mathrm{Pb}$, which led to the production of ${}^{252-254}\mathrm{No}$ isotopes. These studies allowed for evaluation of the performance of TASCA when coupled to a new detector and electronics system. By following these studies, the isotopes of element 114 (${}^{288-291}$114) were produced in irradiations of ${}^{244}\mathrm{Pu}$ targets with ${}^{48}\mathrm{Ca}$ beams at compound nucleus excitation energies around 41.7 and 37.5 MeV, demonstrating TASCA's ability to perform experiments with picobarn-level cross sections. A total of 15 decay chains were observed and were assigned to the decay of ${}^{288-291}$114. A new α-decay branch in ${}^{281}\mathrm{Ds}$ was observed, leading to the new nucleus ${}^{277}\mathrm{Hs}$.

The $\gamma$ decay of excited states in the waiting-point nucleus ${}^{130}\mathrm{Cd}_{82}$ has been observed for the first time. An $8^{+}$ two-quasiparticle isomer has been populated both in the fragmentation of a ${}^{136}\mathrm{Xe}$ beam as well as in projectile fission of ${}^{238}\mathrm{U}$, making ${}^{130}\mathrm{Cd}$ the most neutron-rich $N=82$ isotone for which information about excited states is available. The results, interpreted using state-of-the-art nuclear shell-model calculations, show no evidence of an $N=82$ shell quenching at $Z=48$. They allow us to follow nuclear isomerism throughout a full major neutron shell from ${}^{98}\mathrm{Cd}_{50}$ to ${}^{130}\mathrm{Cd}_{82}$ and reveal, in comparison with ${}^{76}\mathrm{Ni}_{48}$ one major proton shell below, an apparently abnormal scaling of nuclear two-body interactions.