The Neutrons for Science Facility at SPIRAL-2.

The neutrons for science (NFS) facility is a component of SPIRAL-2, the new superconducting linear accelerator built at GANIL in Caen (France). The proton and deuteron beams delivered by the accelerator will allow producing intense neutron fields in the 100 keV-40 MeV energy range. Continuous and quasi-mono-kinetic energy spectra, respectively, will be available at NFS, produced by the interaction of a deuteron beam on a thick Be converter and by the 7Li(p,n) reaction on thin converter. The pulsed neutron beam, with a flux up to two orders of magnitude higher than those of other existing time-of-flight facilities, will open new opportunities of experiments in fundamental research as well as in nuclear data measurements. In addition to the neutron beam, irradiation stations for neutron-, proton- and deuteron-induced reactions will be available for cross-sections measurements and for the irradiation of electronic devices or biological cells. NFS, whose first experiment is foreseen in 2018, will be a very powerful tool for physics, fundamental research as well as applications like the transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors.

Neutron-induced dosimetry reaction cross-section measurements from the threshold up to 20 MeV.

New measured results were obtained for the (58)Ni(n,p)(58)Co, (58)Ni(n,2n)(57)Ni, (58)Ni(n,x)(57)Co, (60)Ni(n,p)(60)Co, (59)Co(n,2n)(58)Co, (59)Co(n,p)(59)Fe, (63)Cu(n,alpha)(60)Co, (204)Pb(n,n')(204 m)Pb and (204)Pb(n,2n)(203)Pb reaction cross-sections. These reactions may be of interest for dosimetry. Measurements were taken at the 7 MV Van de Graaff accelerator at IRMM, Geel, using the activation technique in combination with high-resolution gamma ray spectrometry. The present results are compared with other measurements, evaluated data and model calculations.

Measurement of neutron inelastic scattering cross sections for 52Cr from threshold up to 18 MeV.

The powerful white neutron spectrum from Gelina is used for the investigation of gamma ray production cross sections in the reaction 52Cr(n,n'gamma)52Cr. The gamma rays from the inelastic process are detected with two large volume HPGe detectors placed at 110 degrees and 150 degrees with respect to the beam direction. The neutron flux has been measured with a 235U fission chamber. For the main transitions the inelastic cross section is given with an incident neutron energy resolution ranging from 1.12 keV at 1 MeV to 35.7 keV at 10 MeV, the overall statistical error being <5%. Based on the known 52Cr level scheme, the level and total inelastic cross sections have been obtained up to 3.77 MeV excitation energy. Progress on the implementation of a new acquisition system based on a fast digitiser is presented in this paper.

Gelina neutron target optimisation.

A study is being performed on the properties of the Geel Electron Linear Accelerator (GELINA), a powerful white neutron source, designed for the high-energy resolution time-of-flight measurements. The main aim of this study is to reduce the time spread of neutrons of the given energy without compromising the neutron yield. Both time spread and neutron intensity influence the experimental accuracy of high-resolution neutron cross section measurements, which are particularly important in the resonance region. The quantities of interest have been simulated with coupled electron-photon-neutron steady state and transient MCNP4C3 calculations. Following benchmarking of the code to the properties of the existing target, neutron yield, energy spectra, resolution functions, and neutron and heat spatial distributions have been determined for various alternative geometries and materials. At a fixed accelerator power, actinides deliver the highest neutron yield and a small target provides the best time resolution. The resulting high-power density requires a joint optimisation of the thermal hydraulics and neutronics properties.