[en] We report preliminary results from ultra-fast time-delayed γγ(t) measurements on exotic nuclei just below ¹⁰⁰Sn. The measurements were performed at the LISE spectrometer in GANIL. Nuclei of ⁹⁴Ru and ⁹⁶Pd were populated in the isomeric states via the fragmentation of energetic ¹¹²Cd beam. Preliminary lifetime or lifetime limits are reported for the 6⁺, 4⁺, and 2⁺ states in ⁹⁶Pd and the 4⁺ and 2⁺ states in ⁹⁴Ru. These results indicate an unexpected and strong quenching of the B(E2) strength for the 4⁺ to 2⁺ E2 transition in ⁹⁶Pd in comparison with model predictions and the equivalent B(E2) strength in ⁹⁴Ru. The sequence of quenched B(E2) rates for the 8⁺ → 6⁺ E2 transition in ⁹⁴Ru, 4⁺ → 2⁺E2 transition in ⁹⁶Pd and for the 8⁺ → 6⁺ E2 transition in ⁹⁸Cd, seems to represent a systematic pattern along the N=50 neutron number just below Z=50 and could imply a weak N=50 shell closure when approaching the doubly magic ¹⁰⁰Sn. (author)

[en] The authors describe an experiment for the study of medium spin levels in neutron-rich nuclei around N=20. Especially they present level schemes of ²⁰O, ³²Mg, and ^26,28Ne obtained from in-beam γ-spectra using radioactive beams. (HSI)

[en] An experiment was performed to study excited states in neutron-deficient nuclei around Ca. After a first fragmentation of the primary beam, the one-neutron knockout reaction was used to produce ³⁶Ca ions from the ³⁷Ca secondary beam and in-beam γ rays were measured. The energy of the first excited 2⁺ state in ³⁶Ca and the cross section for the 1-neutron knock-out reaction from ³⁷Ca at ∼ 45 A MeV were obtained. The 2⁺ energy in ³⁶Ca is compared to the mirror nucleus ³⁶S to deduce information on the isospin dependence of the nuclear force near the proton drip line. Furthermore, for two other T_z=-2 nuclei, ²⁸S and ³²Ar, the deexcitation of the first 2⁺ states has been observed. (author)

[en] The aim of this workshop was to discuss the status of experiments at GANIL facility using Exogam with Vamos, Tiara and other ancillary detectors. This document gathers most of the slides that were presented at the workshop, it concerns 8 presentations: 1) the status of Spiral and Spiral-II, 2) the status of Tiara (Tiara array is used for the study of nuclear transfer reactions with radioactive beams in inverse kinematics), 3) data acquisition for the ancillary detectors, 4) the identification of gamma-ray in nuclei around Sm¹³⁰: probing the maximally deformed light rare earth region, 5) the Coulomb excitation of radioactive krypton beams (Kr⁷⁶, Kr⁷⁴), 6) the influence of weakly bound neutrons on fusion around the Coulomb barrier, 7) single particle transfer on doubly-magic Ni⁵⁶, and 8) the study of N=16 for neutron rich nuclei with Ne²⁶(d,p)Ne²⁷ transfer reaction

No abstract available

[en] We have carried out numerical simulation using GEANT code (CERN) in order to define the design of EXOGAM, a future γ-spectrometer for SPIRAL. The effective photopeak efficiency dependence on both the γ energy and multiplicity has been simulated. A choice on the clover segmentation orientation is proposed. Finally, research and development is carried out to study the possibility to localize the radial position of the γ-impact in the crystal using pulse-shape analysis. (authors)

[en] In-beam γ-spectroscopy using fragmentation reactions of radioactive beams have been performed in order to study the structure of excited states in neutron rich oxygen and carbon isotopes. For the produced fragments, γ-ray energies, intensities and γ-γ coincidences have been measured. The experiment was performed at GANIL. New γ-lines have been identified and placed in level schemes for ^17-20C. The non observation of any γ-ray in ^23,24O suggests that their first excited states lie above the neutron threshold. These results are discussed in the framework of shell model calculations

No abstract available

[en] The extensive experimental and theoretical work on the structure of N∼Z, A = 60-80 nuclei revealed many interesting features: large prolate deformations (β = 0.4), strong shape variations as a function of particle number, excitation energy, spin and shape coexistence effects. They are related with drastic changes of properties observed in nuclei with Z≥33 when going from spherical nuclei with N = 50 to neutron deficient nuclei with N = 38 or 40. Both the rapid changes in structure and the shape coexistence appear to reflect the competition between the shell gaps which occur at large oblate and prolate deformations near nucleon numbers 36 and 38 for both protons and neutrons. For N∼Z nuclei the same shell gaps appear simultaneously for both protons and neutrons and reinforce each other. The microscopic structure of the nuclei in the mass region A = 60-80 is essentially determined by the 1g_9/2, 2p_1/2, 1f_5/2 and 2p_3/2 orbitals. Because no unique interpretation of the unusual features discovered in these nuclei exists, the systematic experimental study of structure of these nuclei is still an interesting subject. As part of a systematic experimental study undertaken to investigate the structure of neutron deficient, odd-odd As nuclei, ^68,70,72 As, the level scheme of ⁷⁰ As was investigated using heavy ion induced reactions and in-beam γ-ray spectroscopy techniques. At energies between 500 and 900 keV a multiplet of negative parity levels has been observed. At higher energies a high-spin positive parity sequence of levels starting with a E_x = 1676 keV, J^π 8⁺ level is strongly populated. Additional information is required in order to establish the structure of low and high-spin levels of both parities. The magnetic moments of the 8⁺ and 9⁺ levels have been measured using the time-integral perturbed angular distribution technique and the lifetimes of four levels have been determined using the recoil-distance method. From the measured lifetime for the 9⁺ level a B(M1) ∼ 1μ₀² was extracted for the 9⁺ → 8⁺ transition. The measured magnetic moments for both 8⁺ and 9⁺ levels are in definite disagreement with the presumed two quasi-particle πg_9/2xνg_9/2 configuration, pointing on a more complex configuration for these levels. To explain the measured values for the magnetic moments of the 8⁺ state a {πf_5/2, ν[(f_5/2)_5/2^-3(g_9/2)₈₊²]_21/2-}₈₊ configuration was proposed. A value close to the measured value for the magnetic moment was obtained. The fast M1 transition between 9⁺ and 8⁺ levels gives a further support for this complex structure proposed for positive parity levels. (authors)

[en] The neutron-rich nuclei ₂₁^57,58Sc, ₂₂^58-60Ti, ₂₂^58-60Ti, ₂₃^60-62V, ₂₄^64-66Cr, ₂₅^64-68Mn, ₂₆^67-70Fe and ₂₇^69-71Co have been produced at Ganil via interactions of a 61.8 A.MeV ⁷⁶Ge beam with a ⁵⁸Ni target. Beta-decay studies have been achieved, bringing new half-lives and a better nuclear structure knowledge in this region. These results could help for understanding the overabundances of the neutron-rich stable ⁵⁸Fe, ⁶⁴Ni in certain inclusions of meteorites