Structure of unbound neutron-rich 9^{9}He studied using single-neutron transfer

The 8He(d,p) reaction was studied in inverse kinematics at 15.4A MeV using the MUST2 Si-CsI array in order to shed light on the level structure of 9He. The well known 16O(d,p)17O reaction, performed here in reverse kinematics, was used as a test to validate the experimental methods. The 9He missing mass spectrum was deduced from the kinetic energies and emission angles of the recoiling protons. Several structures were observed above the neutron-emission threshold and the angular distributions were used to deduce the multipolarity of the transitions. This work confirms that the ground state of 9He is located very close to the neutron threshold of 8He and supports the occurrence of parity inversion in 9He.Comment: Exp\'erience GANIL/SPIRAL1/MUST

Modelling LAI at a regional scale with ISBA-A-gs: comparison with satellite-derived LAI over southwestern France

International audienceA CO2-responsive land surface model (the ISBAA- gs model of M´et´eo-France) is used to simulate photosynthesis and Leaf Area Index (LAI) in southwestern France for a 3-year period (2001–2003). A domain of about 170 000 km2 is covered at a spatial resolution of 8 km. The capability of ISBA-A-gs to reproduce the seasonal and the interannual variability of LAI at a regional scale, is assessed with satellite-derived LAI products. One originates from the CYCLOPES programme using SPOT/VEGETATION data, and two products are based on MODIS data. The comparison reveals discrepancies between the satellite LAI estimates and between satellite and simulated LAI values, both in their intensity and in the timing of the leaf onset. The model simulates higher LAI values for the C3 crops than the satellite observations, which may be due to a saturation effect within the satellite signal or to uncertainties in model parameters. The simulated leaf onset presents a significant delay for C3 crops and mountainous grasslands. In-situ observations at a mid-altitude grassland site show that the generic temperature response of photosynthesis used in the model is not appropriate for plants adapted to the cold climatic conditions of the mountainous areas. This study demonstrates the potential of LAI remote sensing products for identifying and locating models' shortcomings at a regional scale

Linear Responses in Time-dependent Hartree-Fock-Bogoliubov Method with Gogny Interaction

A numerical method to integrate the time-dependent Hartree-Fock Bogoliubov (TDHFB) equations with Gogny interaction is proposed. The feasibility of the TDHFB code is illustrated by the conservation of the energy, particle numbers, and center-of-mass in the small amplitude vibrations of oxygen 20. The TDHFB code is applied to the isoscalar quadrupole and/or isovector dipole vibrations in the linear (small amplitude) region in oxygen isotopes (masses A = 18,20,22 and 24), titanium isotopes (A = 44,50,52 and 54), neon isotope (A = 26), and magnesium isotopes (A = 24 and 34). The isoscalar quadrupole and isovector dipole strength functions are calculated from the expectation values of the isoscalar quadrupole and isovector dipole moments.Comment: 10 pages, 13 figure

Spectroscopy of 32Ne and the Island of Inversion

We report on the first spectroscopic study of the N=22 nucleus 32Ne at the newly completed RIKEN Radioactive Ion Beam Factory. A single gamma-ray line with an energy of 722(9) keV was observed in both inelastic scattering of a 226 MeV/u 32Ne beam on a Carbon target and proton removal from 33Na at 245 MeV/u. This transition is assigned to the de-excitation of the first J^pi = 2+ state in 32Ne to the 0+ ground state. Interpreted through comparison with state-of-the-art shell model calculations, the low excitation energy demonstrates that the Island of Inversion extends to at least N=22 for the Ne isotopes.Comment: Accepted for publication in Phys. Rev. Lett. 11 pages, 3 figure

Mediterranean Sea response to climate change in an ensemble of twenty first century scenarios

The Mediterranean climate is expected to become warmer and drier during the twenty-first century. Mediterranean Sea response to climate change could be modulated by the choice of the socio-economic scenario as well as the choice of the boundary conditions mainly the Atlantic hydrography, the river runoff and the atmospheric fluxes. To assess and quantify the sensitivity of the Mediterranean Sea to the twenty-first century climate change, a set of numerical experiments was carried out with the regional ocean model NEMOMED8 set up for the Mediterranean Sea. The model is forced by air–sea fluxes derived from the regional climate model ARPEGE-Climate at a 50-km horizontal resolution. Historical simulations representing the climate of the period 1961–2000 were run to obtain a reference state. From this baseline, various sensitivity experiments were performed for the period 2001–2099, following different socio-economic scenarios based on the Special Report on Emissions Scenarios. For the A2 scenario, the main three boundary forcings (river runoff, near-Atlantic water hydrography and air–sea fluxes) were changed one by one to better identify the role of each forcing in the way the ocean responds to climate change. In two additional simulations (A1B, B1), the scenario is changed, allowing to quantify the socio-economic uncertainty. Our 6-member scenario simulations display a warming and saltening of the Mediterranean. For the 2070–2099 period compared to 1961–1990, the sea surface temperature anomalies range from +1.73 to +2.97 °C and the SSS anomalies spread from +0.48 to +0.89. In most of the cases, we found that the future Mediterranean thermohaline circulation (MTHC) tends to reach a situation similar to the eastern Mediterranean Transient. However, this response is varying depending on the chosen boundary conditions and socio-economic scenarios. Our numerical experiments suggest that the choice of the near-Atlantic surface water evolution, which is very uncertain in General Circulation Models, has the largest impact on the evolution of the Mediterranean water masses, followed by the choice of the socio-economic scenario. The choice of river runoff and atmospheric forcing both have a smaller impact. The state of the MTHC during the historical period is found to have a large influence on the transfer of surface anomalies toward depth. Besides, subsurface currents are substantially modified in the Ionian Sea and the Balearic region. Finally, the response of thermosteric sea level ranges from +34 to +49 cm (2070–2099 vs. 1961–1990), mainly depending on the Atlantic forcing

Absolute and Relative Surrogate Measurements of the \u3csup\u3e236\u3c/sup\u3eU(\u3cem\u3en,f\u3c/em\u3e) Cross Section as a Probe of Angular Momentum Effects

Using both the absolute and relative surrogate techniques, the 236U(n,f) cross section was deduced over an equivalent neutron energy range of 0 to 20 MeV. A 42 MeV 3He beam from the 88 Inch Cyclotron at Lawrence Berkeley National Laboratory was used to perform a (3He,α) pickup reaction on targets of 235U (Jπ=7/2−) and 238U (Jπ = 0+) and the fission decay probabilities were determined. The 235U(3He,αf) and 238U(3He,αf) were surrogates for 233U(n,f) and 236U(n,f), respectively. The cross sections extracted using the surrogate method were compared to directly measured cross sections. The sensitivity of these cross sections to the Jπ -population distributions was explored

Statistical \u3cem\u3eγ\u3c/em\u3e Rays in the Analysis of Surrogate Nuclear Reactions

The surrogate nuclear reaction method is being applied in many efforts to indirectly determine neutron-induced reaction cross sections on short-lived isotopes. This technique aims to extract accurate (n,γ) cross sections from measured decay properties of the compound nucleus of interest (created using a different reaction). The advantages and limitations of a method that identifies the γ-ray decay channel by detecting any high-energy (“statistical”) γ ray emitted during the relaxation of the compound nucleus were investigated. Data collected using the Silicon Telescope Array for Reaction Studies and Livermore-Berkeley Array for Collaborative Experiments silicon and germanium detector arrays were used to study the decay of excited gadolinium nuclei following inelastic proton scattering. In many cases, this method of identifying the γ-ray decay channel can simplify the experimental data collection and greatly improve the detection efficiency for γ-ray cascades. The results show sensitivity to angular-momentum differences between the surrogate reaction and the desired (n,γ) reaction similar to an analysis performed using low-lying discrete transitions even when ratios of cross sections are considered

The SURFEXv7.2 land and ocean surface platform for coupled or offline simulation of Earth surface variables and fluxes

CC Attribution 3.0 License.Final revised paper also available at http://www.geosci-model-dev.net/6/929/2013/gmd-6-929-2013.pdfInternational audienceSURFEX is a new externalized land and ocean surface platform that describes the surface fluxes and the evolution of four types of surface: nature, town, inland water and ocean. It can be run either coupled or in offline mode. It is mostly based on pre-existing, well validated scientific models. It can be used in offline mode (from point scale to global runs) or fully coupled with an atmospheric model. SURFEX is able to simulate fluxes of carbon dioxide, chemical species, continental aerosols, sea salt and snow particles. It also includes a data assimilation module. The main principles of the organization of the surface are described first. Then, a survey is made of the scientific module (including the coupling strategy). Finally the main applications of the code are summarized. The current applications are extremely diverse, ranging from surface monitoring and hydrology to numerical weather prediction and global climate simulations. The validation work undertaken shows that replacing the pre-existing surface models by SURFEX in these applications is usually associated with improved skill, as the numerous scientific developments contained in this community code are used to good advantage

Surrogate Ratio Method in the Actinide Region Using the (\u3cem\u3eα,α\u27f\u3c/em\u3e) Reaction

In the Surrogate Method, the measured decay probability of a compound nucleus formed via a direct reaction is used to extract the cross section for a reaction with a different entrance channel that proceeds through the same compound nucleus. An extension of the Surrogate Method, the Surrogate Ratio Method (SRM), uses a ratio of measured decay probabilities to infer an unknown cross section relative to a known one. To test the SRM we compare the direct-reaction-induced fission probability ratio of 234U(α, α’ f ) to 236U(α, α’f ) with the ratio of cross sections of 233U(n, f ) to 235U(n, f ). These ratios were found to be in agreement over an equivalent neutron energy range of 0.4–18 MeV