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This work features preliminary results from a recent experimental campaign at IFIN-HH, Romania, aimed at measuring lifetimes of excited states in the neutron-rich 180Hf, by means of the RDDS technique. The 181Ta(11B,12C)180Hf proton pick-up reaction was used to populate excited states in the 180Hf nucleus. The ROSPHERE array loaded with 25 HPGe detectors was employed for the detection of the γ transitions depopulating the levels of interest. The array was coupled to the SORCERER particle detector and a plunger device enabling the study of p-γ and p-γ-γ coinciding events. Six different plunger foil distances were chosen, allowing for the construction of the decay curves of the observed γ transitions of interest, from which the corresponding level lifetimes can subsequently be deduced.

The presence of active hydrothermal vent fields near residential areas and their possible link to volcanic activity pose a potential natural hazard to the environment, to society, and to the economy. Despite the importance of risk assessment and mitigation, the monitoring of volcanic activity is hindered by the remoteness and extreme conditions of underwater volcanoes. By developing a mathematical model for geological and physical processes in these environments we shed light on the underlying dynamics of chemical products emitted from the vents and point to the underlying mechanisms that govern potentially hazardous, underwater volcanic environments. Santorini and Nisyros both belong to the Hellenic Volcanic Arc but appear to have different underlying mechanisms. The Generalized Moments Method (GMM) was applied to data gathered from the Northern Caldera of Santorini and the Nisyros caldera, Avyssos, for the purpose of this work, where we focus on the high-frequency recorded CTD data (Conductivity, Temperature, Depth) in the water column over the hydrothermal vents. The data from Santorini were collected in 2017 using an Autonomous Underwater Vehicle (AUV) during the POS510 mission led by GEOMAR, while the data from Nisyros were gathered with the help of a Remotely Operated Vehicle (ROV) in 2010, during the Nautilus expedition.

International audience; The medium-to-heavy mass ytterbium isotopes (70Yb) in the rare-earth mass region are known to be well-deformed nuclei, which can be populated to very high spin, and are predicted to exhibit interesting phenomena, such as shape coexistence. The lack of any experimental information on the structure of the neutron-rich 180Yb isotope and the lifetime of the 21+ state of 178Yb have greatly motivated this study, which can offer useful information for the collective behavior of neutrons and protons in neutron-rich Yb isotopes. A measurement was performed to investigate the population of excited states and a first measurement of the unknown 21+ lifetime of 178Yb by means of a two neutron-transfer reaction 176Yb(18O,16O)178Yb at energies 68-74 MeV using the ROSPHERE array at IFIN-HH, Romania.

The reaction network in the neutron-deficient part of the nuclear chart around A ≈ 100 contains several nuclei of importance to astrophysical processes, such as the p–process. This work reports on the results from recent experimental studies of the radiative proton–capture reactions 112,114Cd(p, γ)113,115 In. Experimental cross sections for the reactions have been measured for proton beam energies residing inside the respective Gamow windows for each reaction, using isotopically enriched 112Cd and 114Cd targets. Two different techniques, the in–beam γ–ray spectroscopy and the activation method have been implemented, where the latter is considered mandatory to account for the presence of low–lying isomers in 113In (E ≈ 392 keV, t1/2 ≈ 100 min), and 115In (E ≈ 336 keV, t1/2 ≈ 4.5 h). Following the measurement of the cross sections, the astrophysical S factors have been subsequently

We present new data about the chemical and structural characteristics of bauxite residue (BR) from Greek Al industry, using a combination of microscopic, analytical, and spectroscopic techniques. SEM-EDS indicated a homogeneous dominant “Al-Fe-Ca-Ti-Si-Na-Cr matrix”, appearing at the microscale. The bulk chemical analyses showed considerable levels of Th (111 μg g−1), along with minor U (15 μg g−1), which are responsible for radioactivity (355 and 133 Bq kg−1 for 232Th and 238U, respectively) with a total dose rate of 295 nGy h−1. Leaching experiments, in conjunction with SFICP- MS, using Mediterranean seawater from Greece, indicated significant release of V, depending on S/L ratio, and negligible release of Th at least after 12 months leaching. STEM-EDS/EELS & HR-STEMHAADF study of the leached BR at the nanoscale revealed that the significant immobility of Th4+ is due to its incorporation into an insoluble perovskite-type phase with major composition of Ca0.8Na0.2TiO3 and crystallites observed in nanoscale. The Th LIII-edge EXAFS spectra demonstrated that Th4+ ions, which are hosted in this novel nano-perovskite of BR, occupy Ca2+ sites, rather than Ti4+ sites. That is most likely the reason of no Th release in Mediterranean seawater.

We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH , 5) crater of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (6Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO2. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe31-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe21-oxidation, dependent on microbially produced nitrate.

The g factor of the 44Cl ground state is measured at the LISE fragment separator at the Grand Accelerateur National d’Ions Lourds (GANIL) using the β nuclear magnetic resonance technique, resulting in g(44Cl) = (−)0.2749(2). An analysis of the g factor value and of the theoretical level scheme in the shell‐model framework reveals the presence of odd‐proton s1/2 configurations and neutron excitation across the N = 28 shell gap in the 44Cl ground state. In addition, the measured g factor strongly supports a 2− spin assignment for the 44Cl ground state.

Almost three quarters of known volcanic activity on Earth occurs in underwater locations. The presence of active hydrothermal vent fields in such environments is a potential natural hazard for the environment, the society, and the economy. Despite its importance for risk assessment and risk mitigation, monitoring of the activity is impeded by the remoteness and the extreme conditions of underwater volcanoes. The large difference of population present on Santorini between the winter and summer seasons, all within a partially enclosed system, make the Santorini-Kolumbo volcanic field, an ideal place for detailed exploration. In 2017, GEOMAR in collaboration with the National and Kapodistrian University of Athens (mission: POS-510 ANYDROS), used an Autonomous Underwater Vehicle (AUV) to map the NE–trending Santorini–Kolumbo line, where it also collected CTD data. Here we present the preliminary results from the 15-hour survey held on the 25th March 2017, during the POS-510 expedition targeting the vent field which is located in the North Basin of Santorini Caldera. Detailed CTD 3D profiles have been reconstructed from the raw data of Santorini’s vent field. An anomaly emerges at the depth of 350 m in the Conductivity and Salinity depth profiles, as the CTD sensor is placed directly above the vent sources. Anomalies were evident in the 3D maps reconstructed, showing for the first time a rather weak, but underlying hydrothermal vent activity at various locations. As the present results are the first ones produced from this expedition, further investigation is required incorporating the full dataset. Based on those results, the impact of developing appropriate mechanisms and policies to avoid the associated natural hazard is expected to be immense.