[en] We study collective vibrational states of the nucleus: giant resonances and multiphonon states. It has been shown that multiphonon states, which are built with several superimposed giant resonances, can be excited in inelastic heavy ion scattering near the grazing angle. No three photon states have been observed until now. An experiment has been performed at GANIL, aiming at the observation of the 3-phonon state built with the giant quadrupole resonance (GQR) in ⁴⁰Ca, with the reaction ⁴⁰Ca + ⁴⁰Ca at 50 A.Me.V. The ejectile was identified in the SPEG spectrometer. Light charged particles were detected in 240 CsI scintillators of the INDRA 4π array. The analysis confirms the previous results about the GQR and the 2-phonon state in ⁴⁰Ca. For the first time, we have measured an important direct decay branch of the GQR by alpha particles. Applying the so-called 'missing energy method' to events containing three protons measured in coincidence with the ejectile, we observe a direct decay branch revealing the presence of a 3-phonon state in the excitation energy region expected for the triple GQR. Dynamical processes are also studied in the inelastic channel, emphasizing a recently discovered mechanism named towing-mode. We observe for the first time the towing-mode of alpha particles. The energies of multiphonon states in ⁴⁰Ca and ²⁰⁸Pb have been computed microscopically including some anharmonicities via boson mapping methods. The basis of the calculation has been extended to the 3-phonon states. Our results show large anharmonicities (several MeV), due to the coupling of 3-phonon states to 2-phonon states. The extension of the basis to 4-phonon states has been performed for the first time. The inclusion of the 4 phonon states in the calculation did not affect the previous observations concerning the 2-phonon states. Preliminary results on the anharmonicities of the 3-phonon states are presented. (author)

[en] At this meeting, we have summarized the actual problematic of reactor antineutrino energy spectra in the frame of fundamental and applied neutrino physics. Nuclear physics is an important ingredient of reactor antineutrino experiments. On the basic science side, these experiments are motivated by neutrino oscillations. This parameter is linked, in the lepton flavor mixing matrix, to the phase characterizing the violation of the CP symmetry. In 2012, the three new generation reactor neutrino experiments, Double Chooz, Daya Bay and Reno have released their first results. These experiments use multi-detectors at reactors, with one or several near detectors placed close to the reactor cores in order to measure the emitted antineutrino flux before it oscillates, and one or several far detectors at a location chosen to maximize the oscillation probability. The design of the detectors should be identical in order to eliminate most of the systematics. In the frame of the Double Chooz experiment, new calculation of reactor antineutrino energy spectra were performed in order to predict the emitted antineutrino energy spectrum that was compared with the far detector measurement during the first phase of the experiment, while the near detector is being built

[en] There have been new developments in the field of applied neutrino physics during the last decade. The International Atomic Energy Agency (IAEA) has expressed interest in the potentialities of antineutrino detection as a new tool for reactor monitoring and has created an ad hoc Working Group in late 2010 to follow the associated research and development. Several research projects are ongoing around the world to build antineutrino detectors dedicated to reactor monitoring, to search for and develop innovative detection techniques, or to simulate and study the characteristics of the antineutrino emission of actual and innovative nuclear reactor designs. We give, in these proceedings, an overview of the relevant properties of antineutrinos, the possibilities of and limitations on their detection, and the status of the development of a variety of compact antineutrino detectors for reactor monitoring

[en] To tackle nuclear material proliferation, we conducted several proliferation scenarios using the MURE (MCNP Utility for Reactor Evolution) code. The MURE code, developed by CNRS laboratories, is a precision, open-source code written in C++ that automates the preparation and computation of successive MCNP (Monte Carlo N-Particle) calculations and solves the Bateman equations in between, for burnup or thermal-hydraulics purposes. In addition, MURE has been completed recently with a module for the CHaracterization of Radioactive Sources, called CHARS, which computes the emitted gamma, beta and alpha rays associated to any fuel composition. Reactor simulations could allow knowing how plutonium or other material generation evolves inside reactors in terms of time and amount. The MURE code is appropriate for this purpose and can also provide knowledge on associated particle emissions. Using MURE, we have both developed a cell simulation of a typical CANDU reactor and a detailed model of light water PWR core, which could be used to analyze the composition of fuel assemblies as a function of time or burnup. MURE is also able to provide, thanks to its extension MURE-CHARTS, the emitted gamma rays from fuel assemblies unloaded from the core at any burnup. Diversion cases of Generation IV reactors have been also developed; a design of Very High Temperature Reactor (a Pebble Bed Reactor (PBR), loaded with UOx, PuOx and ThUOx fuels), and a Na-cooled Fast Breeder Reactor (FBR) (with depleted Uranium or Minor Actinides in the blanket). The loading of Protected Plutonium Production (P3) in the FBR was simulated. The simulations of various reactor designs taking into account reactor physics constraints may bring valuable information to inspectors. At this symposium, we propose to show the results of these reactor simulations as examples of the potentiality of reactor simulations for safeguards. (author)

[en] The ¹¹Be break-up is calculated at 41 MeV per nucleon incident energy on different targets using a nonperturbative time-dependent quantum calculation. The evolution of the neutron halo wave function shows an emission of neutron at large angles for grazing impact parameters and at forward angles for large impact parameters. The neutron angular distribution is deduced for the different targets and compared to experimental data. We emphasize the diversity of diffraction mechanisms, in particular we discuss the interplay of the nuclear effects such as the towing mode and the Coulomb break-up. A good agreement is found with experimental data

[en] The properties of reactor antineutrinos may provide a new mean to monitor non intrusively nuclear power plants. Indeed, antineutrinos energy spectrum and flux depend on the composition of the nuclear fuel and the thermal power of reactor cores. In this context, we present Monte-Carlo full core simulations of a PWR and the method to compute the antineutrino energy spectrum from individual contributions from fission products, using nuclear databases. A set of tools have been developed allowing to perform sensitivity studies to the core simulation parameters and to different fission product nuclear databases. (authors)

[en] The detection of antineutrinos emitted in the decay chains of the fission products in nuclear reactors associated with accurate simulations could provide an isotopic tomography of the core. Nevertheless, their extremely low interaction probability makes the shielding of antineutrinos, practically impossible. In conclusion, such kind of technique could detect a change occurring in the reactor core composition, thus it could be used for non-proliferation purposes. For a declared isotopic composition of the reactor core, the information coming from the antineutrino flux is valuable for the electricity companies which run the reactors in order to increase the precision of the power measurement. In order to be used as a potential safeguard tool, the antineutrino detectors should be a good compromise between detection performances and design constrains related to safety, low cost and size reduction. An example of such detector is SoLid, which will be installed and will take data at SCKCEN/BR2 research reactor, in Belgium. SoLid uses a Lithium-6 based composite scintillator which provides by design a high degree of safety. The design of the detector provides also high detection efficiency as well as maximum robustness against potential background which could fake the antineutrino signal. In consequence, the dimensions of the detector can be reduced without lowering its performances. The combination of Lithium-6 and high segmentation provides ways of imaging the composition of cores, unreachable with a traditional liquid scintillator. A 20 x 20 x 20 cm³ prototype of the SoLid detector has been developed in order to validate the new technology and it takes data at BR2 reactor since August 2013. A larger scale demonstrator able to monitor the reactor in real time will be installed at mid 2015. First results from the prototype system as well as expected performance for the large system will be presented at this symposium. (author)

[en] We show that the non-linearities of large amplitude motions in atomic nuclei induce giant quadrupole and monopole vibrations. As a consequence, the main source of anharmonicity is the coupling with configurations including one of these two giant resonances on top of any state. Two-phonon energies are often lowered by one or two MeV because of the large matrix elements with such three phonon configurations. These effects are studied in two nuclei, ⁴⁰Ca and ²⁰⁸Pb

[en] Nuclear power plants produce large quantities of antineutrinos due to the beta decays of the fission products. Antineutrino measurements could comprise a unique means of providing information on the isotopic composition of the core, non-intrusively and in near real-time. To this aim we have started to study PBRs (Pebble Bed Reactors) with our simulation tools. We use a package called MCNP Utility for Reactor Evolution (MURE), initially developed by CNRS/IN2P3 labs to study Generation IV reactors. The MURE package has been coupled to fission product beta decay nuclear databases for studying reactor antineutrino emission. As a first step, the simulation of a pebble surrounded by He coolant which design is taken from an OECD/NEA benchmark has been performed. Simulations of the evolution of a single-cell for 3 kinds of prospect fuel: uranium, uranium/thorium or PuO_x, are compared with the results of the OECD/NEA benchmark. Various diversion scenarios assuming a 200 MWth reactor are discussed, deduced from our cell calculation, as a first estimate of the antineutrino emission characteristics. The emitted antineutrino characteristics depend on the fuel type, the mixing of regular fuel and proliferation-prone fuel, the pebble residency time. The first gross scenario presented in this paper prove that the usefulness of a neutrino detector is very sensitive to the power of the reactor and the reactor type itself. For the UO_x fuel, we have first focused on the reactor at steady state, which is the most relevant for a first sight, and found that an antineutrino detector of 2m³ placed at 25 m from a reactor of 200 MWth would be sensitive to the diversion of 1 SQ (Significant Quantity) within 3 months, even without taking into account the physics of detection which would enhance the discrepancy between the fissions of uranium and plutonium

[en] The detection of electron antineutrinos emitted in the decay chains of the fission products in nuclear reactors associated with accurate simulations provides an efficient method to assess both the thermal power and the evolution of the core fuel composition. This information could be used by the International Agency for Atomic Energy for safeguarding civil nuclear reactors in the future. The Nucifer experiment aims to demonstrate the concept of ''neutrinometry'' at the pre-industrialized stage. A novel detector has been designed to meet IAEA requirements and it has been deployed at 7 m away from the Osiris research reactor at CEA-Saclay. We report the detector performances and the first detection of neutrinos compared to backgrounds. We discuss the ability of the Nucifer detector to detect a possible non-standard operation of a nuclear reactor. (author)