The recent high-precision measurements of α-particle induced reaction data below the Coulomb barrier (B) make possible the understanding of limits and possible improvement of a previous optical model potential (OMP) for α-particles on nuclei within the mass number range 45≤A≤209 [M. Avrigeanu et al., Phys. Rev. C 82, 014606 (2010)]. An updated version of this potential is given in the present work concerning mainly an increased surface imaginary potential depth well below B for A>130. Moreover, underestimation of reaction cross sections for well-deformed nuclei is removed by using ∼7% larger radius for the surface imaginary part of this spherical OMP. Improved input parameters based on recent independent data, particularly γ-ray strength functions, but no empirical rescaling factor of the γ and/or neutron widths have been involved within statistical model calculation of the corresponding (α, x) reaction cross sections.

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In the frame of refined prompt neutron emission models used for evaluation purposes, the partition of the total excitation energy (TXE) between fully accelerated fission fragments plays an important role. In this work the TXE partition between complementary fission fragments is obtained by taking into account the energy components at scission. The method consists of two steps: the calculation of additional deformation energies of nascent fragments (which are relaxed into excitation energy at full acceleration) and the partition of the available excitation energy at scission (obtained by subtracting the calculated deformation energies from TXE) assuming statistical equilibrium. The obtained fragment excitation energies, as the sum of deformation and excitation energy components at scission, are then used in the frame of the Point-by-Point model to describe experimental data of prompt fission quantities. This TXE partition method was applied to the following fissioning systems: 233,235 U(n th ,f), 239 Pu(n th ,f), 237 Np(n,f) at 0.8 and 5.5 MeV incident energies and 252 Cf(SF). The presented procedure of TXE partition is based exclusively on models and straightforward assumptions practically without the need for adjustable parameters (the parameters have been adjusted a priori and to global systematics). It allows the prediction of prompt neutron emission data and, therefore, may be successfully used for evaluation purposes.

Abstract. 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.