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The reduced transition probabilities B ( E 2 ; 0 g.s. + → 2 1 + , 2 2 + ) in Zn 70 and the full B ( E 2 ; 0 g.s. + → 2 + ) strength up to S n = 7.79 MeV in Ni 68 have been determined at the LISE/GANIL facility using the Coulomb-excitation technique at intermediate beam energy on a Pb 208 target. The γ rays emitted in-flight were detected with an array of 46 BaF 2 crystals. The angles of the deflected nuclei were determined in order to disentangle and extract the Coulomb and nuclear contributions to the excitation of the 2 + states. The measured B ( E 2 ; 0 g.s. + → 2 1 + ) of 1432(124) e 2 fm 4 for Zn 70 falls in the lower part of the published values which clustered either around 1600 or above 2000 e 2 fm 4 , while the B ( E 2 ; 0 g.s. + → 2 2 + ) of 53(7) e 2 fm 4 agrees very well with the two published values. The relatively low B ( E 2 ; 0 g.s. + → 2 1 + ) of 301(38) e 2 fm 4 for Ni 68 agrees with previous studies and confirms a local magicity at Z = 28 , N = 40 . Combining the results of the low-energy spectra of Ni 68 and Zn 70 and their shell-model interpretations, it is interesting to notice that four different shapes (spherical, oblate, prolate, and triaxial) are present. Finally, a summed E 2 strength of only about 150 e 2 fm 4 has been found experimentally at high excitation energy, likely due to proton excitations across the Z = 28 gap. The experimental distribution of this high-energy E 2 excitation agrees with shell-model calculations, but its strength is about two times weaker.

Secondary beams ( 6 Li, 7 Be, 8 B) were obtained by the separation of fragmentation products of a 15 N ion beam (50 MeV/A) impinging on a Be target using the COMBAS spectrometer. The secondary products were detected by a telescope consisting of five Si-detectors (dE) and a stop CsI(Tl) detector. The telescope allowed us to achieve unambiguous particle identification of fragments originating from incident secondary beams as well as their reaction products resulting from interaction with the Si detectors, chosen as a secondary target. This way, break-up reactions of 6 Li, 7 Be and 8 B have been studied in this experiment, in particular the longitudinal momentum distributions of 7 Be fragments in the break-up of 8 B on a Si have been measured at 30 MeV/A.

International audience; The overlap in the mass symmetric region of the reaction products from fusion-fission and quasifission complicates the assignment of symmetric events to complete fusion on the basis of the mass distribution alone. Additional observables, besides mass distribution, should be used. The approach proposed here relies on the fact that fusion-fission and quasifission are characterized by different timescales. Within this framework, we performed a detailed study to find out how timescales can be probed via angular momentum transfer as measured via γ-ray multiplicities. The proof of principle was carried out by measuring the γ rays in coincidence with fusion-fission and quasielastic binary fragments in the reaction S32 + Au197 at beam energy near the Coulomb barrier. The experiment was performed at the Accélérateur Linéaire Tandem à Orsay (ALTO) facility at the Institut De Physique Nucléaire (IPN) in Orsay (France) using a detection setup consisting of ORGAM (ORsay GAMma) and PARIS (Photon Array Radioactive Ion Stable beams) γ-detectors arrays coupled with the CORSET (CORrelation SETup) time-of-flight spectrometer. Results of the sensitivity of this method to distinguish reaction channels with different dynamics are discussed.

The structure of $^{34}$Si was studied through $\gamma$ spectroscopy separately in the $\beta^-$ decays of $^{34}$Mg and $^{34}$Al at the ISOLDE facility of CERN. Different configurations in $^{34}$Si were populated independently from the two recently identified $\beta$-decaying states in $^{34}$Al having spin-parity assignments $J^\pi = 4^-$ dominated by the normal configuration $\pi (d_{5/2})^{-1} \otimes \nu (f_{7/2})$ and $J^\pi = 1^+$ by the intruder configuration $\pi (d_{5/2})^{-1} \otimes \nu (d_{3/2})^{-1}(f_{7/2})^{2}$. The paper reports on spectroscopic properties of $^{34}$Si such as an extended level scheme, spin and parity assignments based on log($ft$) values and $\gamma$-ray branching ratios, absolute $\beta$ feeding intensities and neutron emission probabilities. A total of 11 newly identified levels and 26 transitions were added to the previously known level scheme of $^{34}$Si. Large scale shell-model calculations using the {\sc sdpf-u-mix} interaction, able to treat higher order intruder configurations, are compared with the new results and conclusions are drawn concerning the predictive power of {\sc sdpf-u-mix}, the $N=20$ shell gap, the level of mixing between normal and intruder configurations for the 0$_1^+$, 0$_2^+$ and 2$_1^+$ states and the absence of triaxial deformation in $^{34}$Si.

International audience; Compound nucleus fission and quasi-fission are both binary decay channels whose common properties make the experimental separation between them difficult. A way to achieve this separation could be to probe the angular momentum of the binary fragments. This can be done detecting gamma rays in coincidence with the two fragments. As a case study, the reaction 32S + 197Au near the Coulomb barrier has been performed at the Tandem ALTO facility at IPN ORSAY. ORGAM and PARIS, two different gamma detectors arrays, are coupled with the CORSET detector, a two-arm time-of-flight spectrometer. TOF-TOF data were analyzed to reconstruct the mass-energy distribution of the primary fragments coupled with gamma multiplicity and spectroscopic analysis. Preliminary results of will be shown.

Cross sections and corresponding momentum distributions have been measured for the first time at zero degrees for the exotic nuclei obtained from a beam of 18O at 8.5 MeV/A impinging on a 1 mg/cm2 238U target. Sizable cross sections were found for the production of exotic species arising from the neutron transfer and proton removal from the projectile. Comparisons of experimental results with calculations based on deep-inelastic reaction models, taking into account the particle evaporation process, indicate that zero degree is a scattering angle at which the differential reaction cross section for production of exotic nuclei is at its maximum. This result is important in view of the new generation of zero degrees spectrometers under construction, such as the S3 separator at GANIL, for example. Keywords: Nuclear reactions, Deep-inelastic collisions, Exotic nuclei

A search for shape isomers in the ^{66}Ni nucleus was performed, following old suggestions of various mean-field models and recent ones, based on state-of-the-art Monte Carlo shell model (MCSM), all considering ^{66}Ni as the lightest nuclear system with shape isomerism. By employing the two-neutron transfer reaction induced by an ^{18}O beam on a ^{64}Ni target, at the sub-Coulomb barrier energy of 39 MeV, all three lowest-excited 0^{+} states in ^{66}Ni were populated and their γ decay was observed by γ-coincidence technique. The 0^{+} states lifetimes were assessed with the plunger method, yielding for the 0_{2}^{+}, 0_{3}^{+}, and 0_{4}^{+} decay to the 2_{1}^{+} state the B(E2) values of 4.3, 0.1, and 0.2 Weisskopf units (W.u.), respectively. MCSM calculations correctly predict the existence of all three excited 0^{+} states, pointing to the oblate, spherical, and prolate nature of the consecutive excitations. In addition, they account for the hindrance of the E2 decay from the prolate 0_{4}^{+} to the spherical 2_{1}^{+} state, although overestimating its value. This result makes ^{66}Ni a unique nuclear system, apart from ^{236,238}U, in which a retarded γ transition from a 0^{+} deformed state to a spherical configuration is observed, resembling a shape-isomerlike behavior.

The reduced transition probabilities B(E2; 0+ g.s. → 2+ 1 ) of the 46Ar and 44Ca nuclei were studied using the Coulomb excitation technique at intermediate energy at the LISE/GANIL facility. The in-flight γ rays, emitted after the Coulomb excitation of their first 2+ states, were detected in an array of 64 BaF2 crystals. The present B(E2 ↑) value for 44Ca, 475(36) e2fm4 , agrees well with the value of 495(35) e2fm4 obtained by averaging results of previous experiments. Consistent B(E2; 0+ g.s. → 2+ 1 ) values of 225(29) e2fm4 and 234(19) e2fm4 have been obtained for 46Ar from an absolute and a relative measurement, normalized to the 44Ca value. Both results agree with the ones obtained with the same experimental technique at the NSCL facility but are a factor of 2 smaller than the shell model predictions. The drop in B(E2; 0+ g.s. → 2+ 1 ) in the Ar chain at N = 28, confirmed in this experiment, shows that 46Ar is sensitive to the N = 28 shell closure.

The results of the IS530 experiment at ISOLDE revealed new information concerning several nuclei close to the N ≈ 20 'Island of Inversion' - 34Mg, 34Al, 34Si. The half-life of 34Mg was found to be three times larger than the adopted value (63(1) ms instead of 20(10) ms). The beta-gamma spectroscopy of 34Mg performed for the first time in this experiment, led to the first experimental level scheme for 34Al, also showing that the full beta strength goes through the predicted 1+ isomer in 34Al [1] and/or excited states that deexcite to it. The subsequent beta-decay of the 1+ isomer in 34Al allowed the observation of new gamma lines in 34Si, (tentatively) associated with low-spin high-energy excited states previously unobserved.

Expérience GANIL/LISE3/CATS; International audience; The preliminary value of the reduced transition probability B(E2; 0+ ! 2+1 ) in 46Ar has been determined using the Coulomb excitation technique at intermediate energy. The 46Ar was produced in the fragmentation of a 48Ca beam at GANIL. The -rays following the Coulomb excitation of the 2+1 were emitted in-flight and detected by the 64 BaF2 detectors of the Château de Cristal array. The relatively low B(E2) value of 46Ar reported in this article supports the semi-magic character of this nucleus due to the persistence of the N = 28 shell closure at Z = 18.

The reduced transition probability B(E2: 3/2→7/2 ) has been measured in S using Coulomb excitation at intermediate energy. The nucleus of interest was produced by fragmentation of a Ca beam at GANIL. The reaction products were separated in the LISE spectrometer. After Coulomb-excitation of S in a Pb target, the γ rays emitted inflight were detected by 64 BaF detectors of the Chteau de Cristal array. The preliminary value deduced for the reduced transition probability B(E2: 3/2 →7/2 ) is in agreement with the predictions of the shell model calculations and supports a prolate-spherical shape coexistence in the S nucleus.

This work has been supported by BMBF 06BN109, GA of Czech Republic 202/040791, MICINN-FPA2009-13377, CM-HEPHACOSS2009/ESP-1473 (Spain), the EC through the Eurons project Contracts No. RII3-CT-3/2004-506065, No. OTKA K68801, and No. K100835, the Bolyai Foundation, and by Romanian ANCS, CNCS UEFISCDI, Project No. PN-II-RU-TE-2011- 3-0051. R. B., A. B., F. N., and F. R. acknowledge the IN2P3/ CNRS support

Expérience GANIL/LISE3/EXOGAM; International audience; It is well known that the nuclear shell structure changes for the most exotic nuclei. One of the consequences ofthis phenomenon is the modification of the "classical" magic numbers, as experimentally observed at N = 20 and N = 28.Nevertheless, the mechanisms responsible for such changes are still under discussion and more experimental information isneeded to better constrain the theoretical models. In these proceedings, we report on the discovery and the experimental studyby precise spectroscopy experiments of the 0+2 state in 34Si and 44S. The 34Si is located between the magic spherical 36S andthe deformed 32Mg, member of the so-called island of inversion, whereas 44S is located between the magic spherical 48Caand the deformed 42Si. Therefore, the structure of these nuclei, and in particular the phenomenon of shape coexistence, isof crucial importance to understand how the intruder configurations progressively dominate the ground state structure of themost exotic nuclei at both N = 20 and N = 28.

The 02+ state in Si34 has been populated at the GANIL-LISE3 facility through the β decay of a newly discovered 1 + isomer in Al34 of 26(1) ms half-life. The simultaneous detection of e +e - pairs allowed the determination of the excitation energy E(02+)=2719(3)keV and the half-life T 1/2=19.4(7)ns, from which an electric monopole strength of ρ2(E0)=13.0(0.9)×10 -3 was deduced. The 21+ state is observed to decay both to the 01+ ground state and to the newly observed 02+ state [via a 607(2) keV transition] with a ratio R(21+→01+/21+→02+)=1380(717). Gathering all information, a weak mixing with the 01+ and a large deformation parameter of β=0.29(4) are found for the 02+ state, in good agreement with shell model calculations using a new sdpf-u-mix interaction allowing np-nh excitations across the N=20 shell gap, This work has been supported by BMBF 06BN109, GA of Czech Republic 202/040791, MICINN-FPA2009-13377, CM-HEPHACOSS2009/ESP-1473 (Spain), the EC through the Eurons project Contracts No. RII3-CT-3/2004-506065, No. OTKA K68801, and No. K100835, the Bolyai Foundation, and by Romanian ANCS, CNCS UEFISCDI, Project No. PN-II-RU-TE-2011- 3-0051. R. B., A. B., F. N., and F. R. acknowledge the IN2P3/ CNRS support

We present the results of an experiment in which the structure of neutron-rich nuclei located in the vicinity of N=40 was studied. The importance of our results comes from the fact that knowing the behaviour of the neutron g9/2 orbital with increasing number of neutrons is one of the key points in defining the structure of these nuclei at low excitation energy. The nuclei of interest were produced by fragmentation of a 86Kr beam at 60MeV/u on a thick Be target at GANIL (France). Preliminary results on 75Cu and 78Ga isomers will be presented together with tentative spin and parity assignments.

L'utilisation des fourrages mal ensiles et des divers sous-produits vegetaux dans l'alimentation des vaches laitieres, modifie le nombre des germes dans le lait, et surtout l'espece de la flore microbienne, en faisant augmenter l'incidence des bacteries anaerobies sporulees (Cl. butyricum, Cl. Tyrobutyricum, Cl. sporogenes, etc.). En etant capables de transformer l'acide lactique et l'acide acetique en acide butyrique et en gaz (C02, H2) ces bacteries provoquent beaucoup de difficultes aux fabriques de fromages a pâte cuite et demi-cuite (Emmental, Gouda, Edam, etc.) a cause de l'apparition de proprietes organoleptiques (odeur, gout), fort desagreables, accompagnees du gonflement de ces produits, ce qui les rend impropres a la consommation. Dans les echantillons d'Emmental, prepare a partir de lait obtenu d'animaux fourrages exclusivement au foin, on a trouve de nombreuses bacteries butyriques sans en constater le gonflement ou la modification des qualites sensorielles. Certains chercheurs en ont deduit que les fourrages ensiles, contiennent un facteur inconnu, ou bien une biocenose speciale qui favorise l'alteration alors que d'autres considerent que celle-ci est provoquee seulement par la presence du Cl. tyrobutyricum, les bacteries butyriques habituelles n'etant pas nuisibles ou incomparablement moins nocives [7, 29, 48].