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Further high-precision measurements of α-induced reactions on 64Zn, 108Cd,113,115In, 121,123Sb, and 191,193Ir below the Coulomb barrier have been considered within statistical-model analyses using the previous optical potential. The focus of the work is on eventual uncertainties and/or systematic errors of the OMP assessment at low energies due to the limits in the knowledge of the rest of nuclear model parameters. These parameters were analyzed anyway in advance using independent data, particularly γ-ray strength functions, including their uncertainties. [ABSTRACT FROM AUTHOR]

An extended analysis of the reaction mechanisms involved within deuteron interaction with nuclei, namely the breakup, stripping, pick-up, pre-equilibrium emission, as well as the evaporation from fully equilibrated compound nucleus, is presented, stressing out the key role of the direct interactions. Particular comments concern the deuteron breakup, a comparison of the corresponding parametrization predictions involved in actual model calculations and those of the microscopical models being shown. The overall agreement between the measured data and model calculations validates the description of nuclear mechanisms taken into account for the deuteron-nucleus interaction. Consequently, the lack of direct interactions (especially of the breakup mechanism) in the theoretical frame of the deuteron surrogate reactions should be considered among the main reasons of the failure of associated validation tests. [ABSTRACT FROM AUTHOR]

Numerous domains, in fundamental research as well as in applications, require the study of reactions induced by neutrons with energies from few MeV up to few tens of MeV. Reliablemeasurements also are necessary to improve the evaluated databases used by nuclear transport codes. This energy range covers a large number of topics like transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors. A new facility called Neutrons For Science (NFS) is being built for this purpose on the GANIL site at Caen (France). NFS is composed of a pulsed neutron beam for time-of-flight facility as well as irradiation stations for cross-section measurements. Neutrons will be produced by the interaction of deuteron and proton beams, delivered by the SPIRAL-2 linear accelerator, with thick or thin converters made of beryllium or lithium. Continuous and quasi-mono-energetic spectra will be available at NFS up to 40MeV. In this fast energy region, the neutron flux is expected to be up to 2 orders of magnitude higher than at other existing time-of-flight facilities. In addition, irradiation stations for neutron-, proton- and deuteron-induced reactions will allow performing cross-section measurements by the activation technique. After a description of the facility and its characteristics, the experiments to be performed in the short and medium term will be presented. [ABSTRACT FROM AUTHOR]

A competition of the low-energy Coulomb excitation (CE) with the compound nucleus (CN) formation in α-induced reactions below the Coulomb barrier has recently been assumed in order to make possible the description of the latter as well as the α-particle emission by the same optical model (OM) potential. However, we show in the present work that the corresponding partial waves and integration radii provide evidence for the distinct account of the CE cross section and OM total-reaction cross section σR. Thus the largest contribution to CE cross section comes by far from partial waves larger than the ones contributing to the σR values. Finally, effects of statistical model parameters are comparatively discussed. [ABSTRACT FROM AUTHOR]

An updated optical potential is thus provided for ɑ-particles on nuclei within the mass number range 45≤A≤209, below the Coulomb barrier (B), on the basis of recent high-precision measurements of ɑ-particle induced reaction data below B that made possible the understanding of actual limits and possible improvement of the ɑ-particle optical-model potentials. The main revision concerns actually only the surface imaginary potential depth at the lowest ɑ-particle energies well below B, and in fact only for the mass range above A~130. A further regional point is the underestimation of reaction cross sections for the rare-earth nuclei by using the spherical optical potential unless a 7% larger value of the surface imaginary potential radius is taken into account. Involvement of this potential for further description of both the scattering and ɑ-particles induced reactions is moreover discussed in the present work, of equal interest for nuclear astrophysics and nuclear technology for fusion devices. [ABSTRACT FROM AUTHOR]

An extended analysis of the nuclear reaction mechanisms involved within deuteron interaction with nuclei, namely the breakup, stripping, pick-up, pre-equilibrium emission, and evaporation from fully equilibrated compound nucleus, is presented in order to highlight the importance of the direct mechanisms still neglected in the analysis of deuteron-induced surrogate reactions. Particularly, the dominance of the breakup mechanism at low energies around the Coulomb barrier should be considered in the case of (d,x) surrogate reactions on actinide target nuclei. [ABSTRACT FROM AUTHOR]

The high precision of recent measurements for low-energy α-particle elastic-scattering as well as induced-reaction data makes possible the understanding of actual limits and possible improvement of the global optical model potentials parameters. Involvement of recent optical potentials for reliable description of both the elastic scattering and emission of α-particles, of equal interest for nuclear astrophysics (NA) and nuclear technology (NT) for fusion devices, is discussed in the present work. [ABSTRACT FROM AUTHOR]

Recent accurate data obtained for the isomeric cross section of the 197Au(n, 2n) reaction provides an effective opportunity to consider the question of the effective moment of inertia of the nucleus within a consistent model analysis of all available reaction data for the 197Au target nucleus. Moreover, since the corresponding model assumptions are better validated by analysis of the data above 20-30 MeV where only several data with large uncertainties are known, the usefulness of further measurements to be performed at large-scale facilities as SPIRAL-2 and n_TOF, for incident energies up to 40 as well as 100 MeV, are underlined. [ABSTRACT FROM AUTHOR]

An extended analysis of the reaction mechanisms involved within deuteron interaction with nuclei is presented. An increased attention is devoted to the breakup mechanism, all its components, namely the elastic, inelastic (fusion), and total breakup being carefully considered. Next, the direct reactions represented by the stripping and pick-up mechanisms are discussed. Finally, the pre-equilibrium and compound-nucleus contributions, corrected for the breakup, stripping, and pick-up decrease of the total reaction cross section, complete the deuteron-induced reaction cross section analysis. The overall agreement between the measured data and model calculations validates the description of nuclear mechanisms taken into account for the deuteron-nucleus interaction. [ABSTRACT FROM AUTHOR]

The 'Neutrons for Science' (NFS) facility will be a component of SPIRAL-2, the future accelerator dedicated to the production of very intense radioactive ion beams, under construction at GANIL in Caen (France). NFS will be composed of a pulsed neutron beam for in-flight measurements and irradiation stations for cross-section measurements and material studies. Continuous and quasi-monokinetic energy spectra will be available at NFS respectively produced by the interaction of deuteron beam on thick a Be converter and by the 7Li(p,n) reaction on a thin converter. The flux at NFS will be up to 2 orders of magnitude higher than those of other existing time-of-flight facilities in the 1 MeV to 40 MeV range. NFS will be a very powerful tool for physics and 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. [ABSTRACT FROM AUTHOR]

To improve the reliability of statistical model calculations in the region of heavy proton rich isotopes alpha elastic scattering experiments have been performed at ATOMKI, Debrecen, Hungary. The experiments were carried out at several energies above and below the Coulomb barrier with high precision. The measured angular distributions can be used for testing the predictions of the global and regional optical potential parameter sets. Moreover, we derived the variation of the elastic alpha scattering cross section along the Z = 50 (112Sn–124Sn) isotopic and N = 50 (89Y–92Mo) isotonic chains. In this paper we summarize the efforts to provide high precision experimental angular distributions for several A≈100 nuclei to test the global optical potential parameterizations applied to p-process network calculations. [ABSTRACT FROM AUTHOR]

Semi-microscopic and phenomenological deuterium-nucleus optical potentials have been involved within the analysis of the elastic scattering of deuterons on 6,7Li for energies up to 50 MeV, of interest for calculations of the D-Li neutron source term. Energy-dependent optical potential parameter sets have been obtained. Specific cluster structure effects for d+6Li interaction have been taken into account also by means of the coupled reaction channels method. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Following a semi-microscopic and phenomenological analyses of α-particle elastic scattering on A∼100 nuclei at energies below 32 MeV, a regional optical potential is involved in (n,α) reaction cross-sections analysis for the stable Mo isotopes. Focus on the uncertainties in the OMP parameters found to describe the α-particle emission from excited compound residual nuclei is thus obtained, looking for understanding of the related questions on the basis of microscopic models. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]