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The accurate determination of reactor antineutrino spectra remains a very hot research topic, where new questions have emerged in recent years. Indeed, after the “reactor anomaly” – a deficit of measured antineutrinos at short baseline reactor experiments with respect to spectral predictions – the three international reactor neutrino experiments Double Chooz, Daya Bay and Reno have evidenced spectral distortions in their measurements with respect to the same spectral predictions. This puzzle is called the “shape anomaly”. Recently summation calculations of reactor antineutrino spectra based on the use of nuclear data have obtained the best agreement to date with the reactor neutrino flux measurements at the level of 2% thanks to a decade of Total Absorption Gamma-ray Spectroscopy (TAGS) measurements at the radioactive beam facility of the University of Jyväskylä in two experimental campaigns. A selection of the results obtained so far is presented.

Photoexcitation yields of the 115mIn metastable state were measured with Bremsstrahlung γ beams over a range of endpoint energies between 4.5 and 18 MeV. An effective cross section of the 115In(γ,γ′)115mIn photoexcitation cross section was determinedto reproduce the data. This cross section is built from a cross section calculated with the TALYS code, to which an enhancement is added at about 8.5 MeV.

Fully consistent axially-symmetric-deformed quasiparticle random phase approximation calculations have been performed with the D1S Gogny force. A brief review on the main results obtained in this approach is presented. After a reminder on the method and on the first results concerning giant resonances in deformed Mg and Si isotopes, the multipole responses up to octupole in the deformed and heavy nucleus 238U are discussed. In order to analyse soft dipole modes in exotic nuclei, the dipole responses have been studied in Ne isotopes and in N=16 isotopes, for which results are presented. In these nuclei, the QRPA results on the low lying 2+ states are compared to the 5-Dimensional Collective Hamiltonian ones.

In recent years fully consistent quasiparticle random-phase approximation (QRPA) calculations using finite range Gogny force have been performed to study electromagnetic excitations of several axially-symmetric deformed nuclei up to the 238U. Here we present the extension of this approach to the charge-exchange nuclear excitations (pn-QRPA). In particular we focus on the Gamow-Teller (GT) excitations. A comparison of the predicted GT strength distribution with existing experimental data is presented The role of nuclear deformation is shown. Special attention is paid to β-decay half-lives calculations for which experimental data exist.

We have developed microscopic models for nucleon induced inelastic scattering and one-step direct preequilibrium emission. These models are based on reliable effective in-medium two-body interactions and a microscopic description of the ground and excited states of target nuclei. No arbitrary renormalization process enters our analyzes and the predictions are directly compared to experimental data. The nuclear structure information are obtained in the Random Phase Approximation (RPA) framework with the Gogny force, which provides accurate descriptions of spherical nuclei without pairing. For medium energy (50-200 MeV) proton induced reactions, this approach gives very good predictions for direct inelastic scattering and for the first-step in direct preequilibrium emission. The one-step preequilibrium model has also been extended to fast neutron scattering (10-20 MeV) for the 90Zr target described with RPA theory, and for axially deformed nuclei with a simpler description of the excited states (i.e. particle-hole excitations). Predictions of the reaction model reproduce well experimental data for 90Zr. For deformed targets (232Th and 238U), our calculations underestimate the data at high emission energy. The cross section missing for both actinides may stem from the excitation of vibrational states with excitation energies lower than 5 MeV which are not described with incoherent particle-hole excitations. This defect might be cured if the target spectra are described within the Quasi-particle-RPA (QRPA) theory recently implemented with the Gogny force.