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The activities of the EUROfusion consortium on the development of high quality nuclear data for fusion applications include evaluations of deuteron induced reactions and related data libraries for needs of the DEMO fusion power plant and IFMIF-DONES neutron--source nuclear analyses. Molybdenum is one of the major constituents of the reference stainless steels used in critical components of these projects. While the TENDL deuteron data library was the current reference used by EUROfusion, need of its further improvement has already been pointed out. The weak binding energy of the deuteron is responsible for the high complexity of its interaction with nuclei, involving also a variety of reactions initiated by the nucleons following the deuteron breakup. Their analysis completed that of the deuteron interactions with Mo and its stable isotopes, from elastic scattering to pre-equilibrium and compound--nucleus reactions, up to 50 MeV. A particular attention has been paid to the breakup, stripping, and pick-up direct interactions which amount to around half of the deuteron total--reaction cross section. The due account of most experimental data has validated the present approach, highlighted some prevalent features, and emphasized weak points and consequently the need for modeling/evaluation upgrade., Comment: 31 pages, 25 figures

The scarce data systematics and complexity of deuteron interactions demand the update of both the experimental database and theoretical frame of deuteron activation cross sections. Various reactions induced by neutrons and protons following the deuteron breakup (BU) should be also taken into account. On the other hand, deuteron reaction cross sections recommended recently for high-priority elements are still based on data fit without predictive power. Purpose: Accurate new measurements of low-energy deuteron-induced reaction cross sections for monoisotopic (55Mn) natural manganese target enhance the related database as well as the opportunity of an unitary and consistent account of the related reaction mechanisms. Method: Activation cross sections of 54,56Mn, and 51Cr nuclei by deuterons on $^{55}$Mn were measured at energies <20 MeV by the stacked-foil technique and high resolution gamma spectrometry at the U-120M cyclotron of CANAM, NPI CAS. Then all available data for deuterons on 55Mn up to 50 MeV are analyzed paying particular attention to BU and direct reaction (DR) mechanisms. Results: Newly measured activation cross sections strengthen the deuteron database at low energies, at once with a consistent account for the first time of all available data. Conclusions: Due account of deuteron-induced reactions on 55Mn, including particularly the new experimental data at low energies, is provided by a suitable BU and DR assessment., Comment: 11 pages, 7 figures. arXiv admin note: text overlap with arXiv:1809.02706

Background: Further studies of high-precision measurements of alpha-induced reaction data below the Coulomb barrier have still raised questions about the alpha-particle optical model potential (OMP) within various mass ranges, i.e. for 64Zn, 108Cd, 113,115In, 121,123Sb, and 191,193Ir target nuclei. Purpose: The accuracy as well as eventual uncertainties and/or systematic errors of using a previous optical potential are much better considered by analysis of such accurate data. Method: Statistical model (SM) calculations of the (alpha,x) reaction cross sections have been carried out using model parameters which were previously obtained by analyzing independent data, particularly gamma-ray strength functions, and taking into account their uncertainties and questions of extrapolation for nuclei without similar data. Results: Consistent description of the recent alpha-induced reaction data is provided by the above-mentioned optical potential with no empirical rescaling factors of either its own parameters or the gamma and/or nucleon widths. Effects of still uncertain SM parameters on calculated alpha-induced reaction cross sections and conclusions on the alpha-OMP can be now discussed due to unprecedented precision of the new data. Conclusions: The alpha-particle optical potential has been confirmed at incident energies below the Coulomb barrier using statistical-model parameters validated through a former analysis of independent data., Comment: 14 pages, 6 figures

Purpose: Accurate new measurements of low-energy deuteron-induced reaction cross sections for natural Cr target can enhance the related database and the opportunity for an unitary and consistent account of the involved reaction mechanisms. Methods: The activation cross sections of $^{51,52,54}$Mn, $^{51}$Cr, and $^{48}$V nuclei for deuterons incident on natural Cr at energies up to 20 MeV, were measured by the stacked-foil technique and high resolution gamma spectrometry using U-120M cyclotron of the Center of Accelerators and Nuclear Analytical Methods (CANAM) of the Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS). They as well as formerly available data for deuteron interactions with Cr isotopes up to 60 MeV are the object of an extended analysis of all processes from elastic scattering until the evaporation from fully equilibrated compound system, but with a particular attention given to the BU and DR mechanisms. Results: The new measured activation excitation functions proved essential for the enrichment of the deuteron database, while the theoretical analysis of all available data strengthens for the first time their consistent account provided that (i) a suitable BU and DR assessment is completed by (ii) the assumption of PE and CN contributions corrected for decrease of the total-reaction cross section due to the leakage of the initial deuteron flux towards BU and DR processes. Conclusions: The suitable description of nuclear mechanisms involved within deuteron-induced reactions on chromium, taking into account especially the BU and DR direct processes, is validated by an overall agreement of the calculated and measured cross sections including particularly the new experimental data at low energies., Comment: 15 pages, 14 figures, accepted for publication in Phys. Rev. C

Background: Challenging questions of the $\alpha$-particle optical-model potential (OMP) are still pointed out by recent high-precision measurements of $\alpha$-induced reaction data below the Coulomb barrier. Moreover, the reliability of a previous OMP for $\alpha$-particles on nuclei within the mass number range 45$\leq$$A$$\leq$209 has been recently proved for emitted $\alpha$ particles as well, but only in the case of proton-induced reactions on Zn isotopes [Phys. Rev. C {\bf 91}, 064611 (2015), Paper I]. Purpose: Analysis of most recent $(\alpha,\gamma)$ reaction data for Ge and Zr isotopes, which provides an additional validation of the above-mentioned potential, is related to a further account of $\alpha$-particle emission in neutron-induced reactions on Zr isotopes, at the same time with a suitable description of all competitive processes. Methods: A consistent parameter set, established or validated by independent analysis of recent various data, particularly $\gamma$-ray strength functions, have been involved within model calculation of the $(\alpha,\gamma)$ as well as $(n,\alpha)$ reaction cross sections. The latter are part of the whole analysis of the neutron activation of Zr isotopes, in order to avoid any error compensation or latent ambiguity. Results: The aforesaid potential provides a consistent description of recent $\alpha$-induced reaction data with no empirical rescaling factors of the $\gamma$ and/or nucleon widths. On the other hand, its use leads to underestimated predictions of the pre-equilibrium emission and statistical models for the $(n,\alpha)$ reaction cross sections. Conclusions: An optical potential with a volume imaginary component seems to be needed to describe the low-energy $\alpha$-particle evaporation, while only surface absorption occurs in $\alpha$-induced reactions at similar energies., Comment: 18 pages, 11 figures, accepted for publication in Phys. Rev. C

An extended analysis of the key role of direct interactions, i.e., breakup, stripping and pick-up processes, has been carried out for deuteron-induced reactions. Particular comments concern the deuteron breakup which is the dominant mechanism involved in surrogate reactions on heavy nuclei, around the Coulomb barrier., Comment: 5 pages, 3 figures. Contribution at Int. Conf. on Nucl. Data for Science and Technology (ND2016), 11-16.09.2016, Bruges, Belgium

Comparative assessment of the total breakup proton-emission cross sections measured for 56 MeV deuteron interaction with target nuclei from $^{12}$C to $^{209}$Bi, with an empirical parametrization and recently calculated microscopic neutron-removal cross sections has been done at the same time with similar data measured at 15, 25.5, 70, and 80 MeV. Comparable mass dependances of the elastic-breakup (EB) cross sections provided by the empirical parametrization and the microscopic results have been also found at the deuteron energy of 56 MeV, while the assessment of absolute-values variance up to a factor of two has been not possible due to the lack of EB measurements at energies higher than 25.5 MeV. While the similarities represent an additional validation of the microscopic calculations, the cross-section difference should be considered within the objectives of further measurements., Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev. C

Background: Recent high-precision measurements of alpha-induced reaction data below the Coulomb barrier have pointed out questions of the alpha-particle optical-model potential (OMP) which are yet open within various mass ranges. Purpose: The applicability of a previous optical potential and eventual uncertainties and/or systematic errors of the OMP assessment at low energies can be further considered on this basis. Method: Nuclear model parameters based on the analysis of recent independent data, particularly gamma-ray strength functions, have been involved within statistical model calculation of the (alpha,x) reaction cross sections. Results: The above-mentioned potential provides a consistent description of the recent alpha-induced reaction data with no empirical rescaling factors of the and/or nucleon widths. Conclusions: A suitable assessment of alpha-particle optical potential below the Coulomb barrier should involve the statistical-model parameters beyond this potential on the basis of a former analysis of independent data., Comment: 12 pages, 8 figures. Updated citations. Minor correction

A competition of the low-energy Coulomb excitation (CE) with the compound nucleus (CN) formation in $\alpha$-induced reactions below the Coulomb barrier has been assumed by Rauscher [Phys. Rev. Lett. 111, 061104 (2013)] in order to use the same optical model (OM) potential for description of the latter and the alpha-particle emission as well. In this Comment we show 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., Comment: 2 pages, 1 figure. Reduced length, title changed

The recent high-precision measurements of alpha-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 alpha-particles on nuclei within the mass number range 45130. 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 gamma-ray strength functions, but no empirical rescaling factor of the gamma and/or neutron widths have been involved within statistical model calculation of the corresponding (alpha,x) reaction cross sections., Comment: 14 pages, 11 figures, accepted for publication in Phys. Rev. C

An analysis of the $^{231}$Pa$(d,3n)$$^{230}$U reaction excitation function at energies around the Coulomb barrier has taken into account the pre-equilibrium and compound-nucleus cross sections corrected for the deuteron-breakup decrease of the total reaction cross section, as well as the inelastic breakup enhancement. The analysis reveals the dominance of the deuteron breakup mechanism unlike a former assessment in this respect of the deuteron-induced fission process., Comment: 5 pages, 3 figures

Recent accurate data obtained for the isomeric cross section of the $^{197}$Au$(n,2n)$ reaction provide a valuable opportunity to consider the question of the effective moment of inertia of the nucleus within a local consistent model analysis of all available reaction data for the $^{197}$Au target nucleus. Thus, a definite proof of a moment of inertia equal to that of the rigid--body has been obtained for $^{196}$Au nucleus while an inference of the half rigid--body value is suggested for the $^{194}$Ir nucleus. The usefulness of further measurements at incident energies up to $\ge$40 MeV has also been proved., Comment: 5 pages, 5 figures

The activation cross sections of (d,p), (d,2n), (d,3n), and (d,2p) reactions on 63,65Cu were measured in the energy range from 4 to 20 MeV using the stacked-foils technique. Then, following the available elastic-scattering data analysis that provided the optical potential for reaction cross sections calculations, an increased effort has been devoted to the breakup mechanism, the direct reaction stripping, and the pre-equilibrium and compound-nucleus cross section calculations, corrected for the breakup and stripping decrease of the total reaction cross section. The overall agreement between the measured and calculated deuteron activation cross sections proves the correctness of the nuclear mechanisms account, next to the simultaneous analysis of the elastic-scattering and reaction data., Comment: 14 pages, 6 figures, accepted for publication in Phys. Rev. C

We show that the model analysis of new measured (d,p), (d,t), (6He,5He), and (6He,4He) reaction cross sections at incident energies around the Coulomb barrier (J. Phys. G: Nucl. Part. Phys. 38 (2011) 035106) led to results that are not consistent with similar calculated and evaluated data. On the other hand, it should be corrected by taking into account the direct processes., Comment: 5 pages, 1 figure, in: M. Avrigeanu, Report EFFDOC-1136, EFF/EAF Meeting, OECD/NEA, Issy-les-Moulineaux, France, 10 May 2011; submitted to: J. Phys. G: Nucl. Phys

Elastic scattering cross sections of the $^{89}$Y($\alpha$,$\alpha$)$^{89}$Y reaction have been measured at energies E$_{c.m.}$ = 15.51 and 18.63 MeV. The high precision data for the semi-magic $N = 50$ nucleus $^{89}$Y are used to derive a local potential and to evaluate the predictions of global and regional $\alpha$-nucleus potentials. The variation of the elastic alpha scattering cross sections along the $N = 50$ isotonic chain is investigated by a study of the ratios of angular distributions for $^{89}$Y($\alpha$,$\alpha$)$^{89}$Y and $^{92}$Mo($\alpha$,$\alpha$)$^{92}$Mo at E$_{c.m.} \approx$ 15.51 and 18.63 MeV. This ratio is a very sensitive probe at energies close to the Coulomb barrier, where scattering data alone is usually not enough to characterize the different potentials. Furthermore, $\alpha$-cluster states in $^{93}$Nb = $^{89}$Y $\otimes$ $\alpha$ are investigated.

Novel measurements of $(\alpha,\gamma)$ and $(\alpha$,n) reaction cross sections on the target nucleus $^{151}$Eu, close to the reaction thresholds, support the setting up of recent parameters of the $\alpha$-particle optical model potential below the Coulomb barrier. A better understanding of the $\alpha$-particle optical potential at these energies leads to a statistical model analysis of additional partial cross sections that were formerly measured but not considered within the model analysis. On this basis we have tentatively assigned a modified $J^{\pi}$=9$^-$ spin and parity to the 22.7-h isomer in $^{154}$Tb., Comment: 3 pages, 2 figures

$(\alpha,\gamma)$ and $(\alpha$,n) reaction cross sections recently measured close to the reaction thresholds are rather well described by a previously developed regional optical potential. Thus, particular features of the $\alpha$-particle optical potential at energies below the Coulomb barrier, besides parameters describing $\alpha$-particle elastic scattering at higher energies are confirmed. Additional limitations of similar statistical model calculations for minor reaction channels are shown to be most likely due to an overlooked process or critical values of statistical model parameters around closed nuclear shells., Comment: 4 pages, 3 figures

A previously derived semi-microscopic analysis based on the Double Folding Model, for alpha-particle elastic scattering on A~100 nuclei at energies below 32 MeV, is extended to medium mass A ~ 50-120 nuclei and energies from ~13 to 50 MeV. The energy-dependent phenomenological imaginary part for this semi-microscopic optical model potential was obtained including the dispersive correction to the microscopic real potential, and used within a concurrent phenomenological analysis of the same data basis. A regional parameter set for low-energy alpha-particles entirely based on elastic-scattering data analysis was also obtained for nuclei within the above-mentioned mass and energy ranges. Then, an ultimate assessment of (alpha,gamma), (alpha,n) and (alpha,p) reaction cross sections concerned target nuclei from 45Sc to 118Sn and incident energies below ~12 MeV. The former diffuseness of the real part of optical potential as well as the surface imaginary-potential depth have been found responsible for the actual difficulties in the description of these data, and modified in order to obtain an optical potential which describe equally well both the low energy elastic-scattering and induced-reaction data of alpha-particles., Comment: 46 pages, 16 figures. n_TOF Collaboration Annual Meeting, Bari, Italy, 28-30 November 2007 (http://www.cern.ch/ntof/Documents/bari_nov07/bari_slides.php); revised version accepted for publication in ADNDT

Excitation functions were measured for the $^{55}$Mn(n,2n)$^{54}$Mn, $^{55}$Mn(n,$\alpha$)$^{52}$V, $^{63}$Cu(n,$\alpha$)$^{60}$Co, $^{65}$Cu(n,2n)$^{64}$Cu, and $^{65}$Cu(n,p)$^{65}$Ni reactions from 13.47 to 14.83 MeV. The experimental cross sections are compared with the results of calculations including all activation channels for the stable isotopes of Mn and Cu, for neutron incident energies up to 50 MeV. Within the energy range up to 20 MeV the model calculations are most sensitive to the parameters related to nuclei in the early stages of the reaction, while the model assumptions are better established by analysis of the data in the energy range 20-40 MeV. While the present analysis has taken advantage of both a new set of accurate measured cross sections around 14 MeV and the larger data basis fortunately available between 20 and 40 MeV for the Mn and Cu isotopes, the need of additional measurements below as well as above 40 MeV is pointed out. Keywords: 55Mn, 63,65Cu, E$\leq$40 MeV, Neutron activation cross section measurements, Nuclear reactions, Model calculations, Manganese, Copper, Comment: 39 pages, 12 figures

The real part of the optical potential for the nucleon-nucleus scattering at lower energies (E_i<100MeV) has been calculated including nucleonic and mesonic form factors by a double folding approach. Realistic density- and energy-dependent effective NN-interactions DDM3Y, BDM3Y and HLM3Y based on the Reid and Paris potentials are used in this respect. The effects of the nucleon density distribution and the average relative momentum on the folded potential have been analysed. A good agreement with the phenomenological potential of Lagrange-Lejeune, as well as with the parametrization of Jeukenne-Lejeune-Mahaux for both neutron and proton double-folded potentials is obtained. The results indicate that the strongly simplified model interactions used in preequilibrium reaction theory neglect important dynamical details of such processes., Comment: 10 pages, 4 ps figures, REVTeX, submitted to Phys.Rev.C

The main formalisms of partial level densities (PLD) used in preequilibrium nuclear reaction models, based on the equidistant spacing model (ESM), are considered. A collection of FORTRAN77 functions for PLD calculation by using 14 formalisms for the related partial-state densities is provided and 28 sample cases (73 versions) are described. The results are given in graphic form too. Composite (recommended) formulas, which include the optional use of various corrections, i.e. the advanced pairing and shell correction in addition to the Pauli effect, and average energy-dependent single-particle level densities for the excited particles and holes, are also given. The formalism comprises the density of particle-hole bound states, and the effects of an exact correction for the Pauli-exclusion principle are considered. Keywords: Partial nuclear level density; Nuclear level density; Single-particle level density; Equidistant-spacing model; Preequilibrium emission; Nuclear reactions, Comment: 34 pages, RevTeX, 14 postscript figures. Accepted for publication in Comp. Phys. Comm

The correct use of energy-dependent single-particle level (s.p.l.) densities within particle-hole state densities based on the equidistant spacing model (ESM) is analysed. First, an analytical expression is obtained following the convolution of energy-dependent excited-particle and hole densities. Next, a comparison is made with results of the ESM formula using average s.p.l. densities for the excited particles and holes, respectively. The Fermi-gas model (FGM) s.p.l. densities calculated at the corresponding average excitation energies are used in both cases. The analysis concerns also the density of particle-hole bound states. The pairing correlations are taken into account while the comparison of various effects includes the exact correction for the Pauli exclusion principle. Quantum-mechanical s.p.l. densities and the continuum effect can also match a corresponding FGM formula, suitable for use within the average energy-dependent partial state density in multistep reaction models., Comment: 29 pages, ReVTeX, 11 postscript figures, submitted to Phys.Rev.C