SPIRAL2 at GANIL: A world leading ISOL facility at the dawn of the next decade

International audienceTo pursue the investigation of a new territory of nuclei with extreme N/Z, called "terra incognita", several projects, all aiming at the increase by several orders of magnitude of RIB intensities are now under discussion worldwide. In Europe, two major new projects have been approved recently: FAIR@GSI, using the so-called "in-flight" method, and SPIRAL2@GANIL, based on the ISOL method. The main goal of SPIRAL2 is clearly to extend our knowledge of the limit of existence and the structure of nuclei deeply in the medium and heavy mass region (A=60-140), which is today an almost unexplored continent. SPIRAL2 is based on a high power, CW, superconducting driver LINAC, delivering 5 mA of deuteron beams at 40 MeV (200 kW) directed on a C converter+ Uranium target and producing therefore more than 1013 fissions/s. The expected radioactive beam intensities for exotic species in the mass range from A=60 to A=140, of the order of 106-1010 pps will surpass by two order of magnitude any existing facility in the world. These unstable atoms will be available at energies between a few keV/n to 15 MeV/n. The same driver will accelerate high intensity (100 μA to 1 mA), heavier ions up to Ar at 14 MeV/n producing also proton rich exotic nuclei. In applied areas SPIRAL2 is considered as a powerful variable energy neutron source, a must for studying the impact of nuclear fission and fusion on materials. The intensities of these unstable species are excellent opportunities for new tracers and diagnostics either for solid state, material or for radiobiological science and medicine. The technical design has reached the point where SPIRAL2 is ready for construction. Project status and foreseen schedules will be presented. Scientific and technical R&D programs in collaboration with EU and International partners for the facility as well as for the associated innovative new instruments will be discussed

GANIL-SPIRAL2 : a new era

International audienceGANIL presently offers unique opportunities in nuclear physics and many other fields that arise from not only the provision of low-energy stable beams, fragmentation beams and re-accelerated radioactive species, but also from the availability of a wide range of state-of-the-art spectrometers and instrumentation. An overview of the physics with secondary beams carried out at GANIL is presented. Selected examples of recent experiments using fragmentation of high energy intense stable heavy ions beams and reaccelerated SPIRAL1 "exotic" beams and the associated instruments are used to illustrate the ongoing physics program. With the construction of SPIRAL2 over the next few years, GANIL is in a good position to retain its world-leading capability. As selected by the ESFRI committee, the next generation of ISOL facility in Europe is represented by the SPIRAL2 project to be built at GANIL (Caen, France). The future prospects of the accelerator complex GANIL-SPIRAL1 and the path towards SPIRAL2 is also briefly introduced

Quasi-particules loin de la mer de Fermi

École thématiqu

Quasiparticle RPA with finite rank approximation for Skyrme interactions

A finite rank separable approximation for the particle-hole RPA calculations with Skyrme interactions is extended to take into account the pairing. As an illustration of the method energies and transition probabilities for the quadrupole and octupole excitations in some O, Ar, Sn and Pb isotopes are calculated. The values obtained within our approach are very close to those that were calculated within QRPA with the full Skyrme interaction. They are in reasonable agreement with experimental data.Comment: 20 pages, 1 figure, submitted to Phys.Rev.

Separabelized Skyrme Interactions and Quasiparticle RPA

A finite rank separable approximation for the quasiparticle RPA with Skyrme interactions is applied to study the low lying quadrupole and octupole states in some S isotopes and giant resonances in some spherical nuclei. It is shown that characteristics calculated within the suggested approach are in a good agreement with available experimental data.Comment: 12 pages, 2 figures, proceedings of the Seventh School-Seminar on Heavy Ion Physics, Dubna, Russia, May 27-June 1, 2002; to appear in Physics of Atomic Nucle

Europe as a multilevel federation

Peer reviewedPublisher PD

Single-neutron transfer from 11Be gs via the (p,d) reaction with a radioactive beam

The 11Be(p,d)10Be reaction has been performed in inverse kinematics with a radioactive 11Be beam of E/A = 35.3 MeV. Angular distributions for the 0+ ground state, the 2+, 3.37 MeV state and the multiplet of states around 6 MeV in 10Be were measured at angles up to 16 deg CM by detecting the 10Be in a dispersion-matched spectrometer and the coincident deuterons in a silicon array. Distorted wave and coupled-channels calculations have been performed to investigate the amount of 2+ core excitation in 11Be gs. The use of "realistic" 11Be wave functions is emphasised and bound state form factors have been obtained by solving the particle-vibration coupling equations. This calculation gives a dominant 2s component in the 11Be gs wave function with a 16% [2+ x 1d] core excitation admixture. Cross sections calculated with these form factors are in good agreement with the present data. The Separation Energy prescription for the bound state wave function also gives satisfactory fits to the data, but leads to a significantly larger [2 x 1d] component in 11Be gs.Comment: 39 pages, 12 figures. Accepted for publication in Nuclear Physics A. Added minor corrections made in proof to pages 26 and 3

Study of the N=50 major shell effect close to 78^{78}Ni : First evidence of a weak coupling structure in 83_32^{83}\_{32}Ge_51\_{51} and three-proton configuration states in 81_31^{81}\_{31}Ga_50\_{50}

New levels were attributed to $^{81}\_{31}$Ga$\_{50}$ and $^{83}\_{32}$Ge$\_{51}$ which were fed by the $\beta$-decay of their respective mother nuclei $^{81}\_{30}$Zn$\_{51}$ and $^{83}\_{31}$Ga$\_{52}$ produced by fission at the "PARRNe" ISOL set-up installed at the Tandem accelerator of the Institut de Physique Nucl\'eaire, Orsay. We show that the low energy structure of $^{81}\_{31}$Ga$\_{50}$ and $^{83}\_{32}$Ge$\_{51}$ can easily be explained within the natural hypothesis of a strong energy gap at N=50 and a doubly-magic character for $^{78}$Ni.Comment: 2 pages, pdf file, To be published in the Proceedings of "International Symposium on Structure of Exotic Nuclei and Nuclear Forces (SENUF 06)", March 2006, Tokyo, Japa

The decline and rise of neighbourhoods: the importance of neighbourhood governance

There is a substantial literature on the explanation of neighbourhood change. Most of this literature concentrates on identifying factors and developments behind processes of decline. This paper reviews the literature, focusing on the identification of patterns of neighbourhood change, and argues that the concept of neighbourhood governance is a missing link in attempts to explain these patterns. Including neighbourhood governance in the explanations of neighbourhood change and decline will produce better explanatory models and, finally, a better view about what is actually steering neighbourhood change