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Inelastic and multi-nucleon transfer reactions between a $^{238}$U beam, accelerated at 6.14 MeV/u, and a $^{12}$C target were used for the production of neutron-rich, fissioning systems from U to Cm. A Si telescope, devoted to the detection of the target-like nuclei, provided a characterization of the fissioning systems in atomic and mass numbers, as well as in excitation energy. Cross-sections, angular and excitation-energy distributions were measured for the inelastic and transfer channels. Possible excitations of the target-like nuclei were experimentally investigated for the first time, by means of g -ray measurements. The decays from the first excited states of $^{12}$C, $^{11}$B and $^{10}$Be were observed with probabilities of 0.12 - 0.14, while no evidence for the population of higher-lying states was found. Moreover, the fission probabilities of $^{238}$U, $^{239}$Np and $^{240,241,242}$Pu and $^{244}$Cm were determined as a function of the excitation energy., Comment: 16 pages, 12 figures

Linear polarization measurements have been performed for $\gamma$-rays in $^{91}$Ru produced with the $^{58}$Ni($^{36}$Ar, $2p1n$$\gamma$)$^{91}$Ru reaction at a beam energy of 111 MeV. The EXOGAM Ge clover array has been used to measure the $\gamma$-$\gamma$ coincidences, $\gamma$-ray linear polarization and $\gamma$-ray angular distributions. The polarization sensitivity of the EXOGAM clover detectors acting as Compton polarimeters has been determined in the energy range 0.3$-$1.3 MeV. Several transitions have been observed for the first time. Measurements of linear polarization and angular distribution have led to the firm assignments of spin differences and parity of high-spin states in $^{91}$Ru. More specifically, calculations using a semi-empirical shell model were performed to understand the structures of the first and second (21/2$^{+}$) and (17/2$^{+}$) levels. The results are in good agreement with the experimental data, supporting the interpretation of the non yrast (21/2$^{+}$) and (17/2$^{+}$) states in terms of the $J_{\rm max}$ and $J_{\rm max}-2$ members of the seniority-three $\nu(g_{9/2})^{-3}$ multiplet., Comment: 19 pages, 8 figures, 2 tables

We report on the observation of a new isomeric state in $^{68}$Ni. We suggest that the newly observed state at 168(1) keV above the first 2$^+$ state is a $\pi(2p-2h)$ 0$^{+}$ state across the major Z=28 shell gap. Comparison with theoretical calculations indicates a pure proton intruder configuration and the deduced low-lying structure of this key nucleus suggests a possible shape coexistence scenario involving a highly deformed state., Comment: 5 pages, 3 figures, accepted for publication in Physical Review C

Lifetimes of the $9/2^-_1$ and $3/2^-_1$ states in $^{63}$Co and the $9/2^-_1$ state in $^{65}$Co were measured using the recoil distance Doppler shift and the differential decay curve methods. The nuclei were populated by multi-nucleon transfer reactions in inverse kinematics. Gamma rays were measured with the EXOGAM Ge array and the recoiling fragments were fully identified using the large-acceptance VAMOS spectrometer. The E2 transition probabilities from the $3/2^-_1$ and $9/2^-_1$ states to the $7/2^-$ ground state could be extracted in $^{63}$Co as well as an upper limit for the $9/2^-_1\rightarrow7/2^-_1$ $B$(E2) value in $^{65}$Co. The experimental results were compared to large-scale shell-model calculations in the $pf$ and $pfg_{9/2}$ model spaces, allowing to draw conclusions on the single-particle or collective nature of the various states., Comment: 8 pages, 8 figures, 1 table, accepted for publication in Physical Review C

We report here the first direct lifetime measurement of the 2+1 state in 72,74Zn. The neutron-rich beam was produced by in-flight fragmentation of 76Ge at the Grand Acc\'el\'erateur National d'Ions Lourds and separated with the LISE spectrometer. The 2+1 state was excited by inelastic scattering and knock-out reaction on a CD2 target and its lifetime was measured by the recoil-distance Dopplershift method with the K\"oln plunger device combined with the EXOGAM detectors. The lifetimes of the 2+1 states in 72,74Zn were determined to be 17.9(18) and 27.0(24) ps, which correspond to reduced transition probabilities B(E2; 2+1 \rightarrow 0+) = 385(39) and 370(33) e2fm4, respectively. These values support the idea of a systematic maximum of collectivity at N = 42 for Zn, Ge and Se nuclei. In addition, the available systematics in the neighboring nuclei point towards a transition from a spherical oscillator at N = 40 to complete {\gamma}-softness at N = 42., Comment: 10 pages, 13 figures; accepted for publication in Phys. Rev. C

The general phenomenon of shell structure in atomic nuclei has been understood since the pioneering work of Goeppert-Mayer, Haxel, Jensen and Suess.They realized that the experimental evidence for nuclear magic numbers could be explained by introducing a strong spin-orbit interaction in the nuclear shell model potential. However, our detailed knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers ($N = Z$), the unique nature of the atomic nucleus as an object composed of two distinct types of fermions can be expressed as enhanced correlations arising between neutrons and protons occupying orbitals with the same quantum numbers. Such correlations have been predicted to favor a new type of nuclear superfluidity; isoscalar neutron-proton pairing, in addition to normal isovector pairing (see Fig. 1). Despite many experimental efforts these predictions have not been confirmed. Here, we report on the first observation of excited states in $N = Z = 46$ nucleus $^{92}$Pd. Gamma rays emitted following the $^{58}$Ni($^{36}$Ar,2$n$)$^{92}$Pd fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution {\gamma}-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling) in the ground and low-lying excited states of the heaviest N = Z nuclei. The strong isoscalar neutron- proton correlations in these $N = Z$ nuclei are predicted to have a considerable impact on their level structures, and to influence the dynamics of the stellar rapid proton capture nucleosynthesis process., Comment: 13 pages, 3 figures