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The assessment of an α -particle optical model potential for nucleon–induced α -emission within the A ∼ 60 mass-number range [Avrigeanu and Avrigeanu (Eur. Phys. J. A 57:54, 2021)] is completed by analysis of neutron–induced reactions on stable Ni isotopes. The same consistent set of nuclear–model input parameters as well as first uncertainty analysis of calculated cross sections related to the accuracy of independent data formerly used within parameter setting up have been concerned. Description of absorption and emission of α -particles by the same potential is validated, while the pickup direct reaction and Giant Quadrupole Resonance (GQR) α -emission beyond the statistical predictions are confirmed by recent data around the GQR energies. [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. Reliable measurements 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 40 MeV. 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.

A consistent set of statistical-model input parameters, validated by analysis of various independent data, makes possible the assessment of an α -particle optical model potential [Phys. Rev. C 90, 044612 (2014)] also for nucleon-induced α -emission within the A ∼ 60 mass-number range. The advantage of recent data for low-lying states feeding is taken as well. Consideration of additional reaction channels leading to increase of the α -emission beyond the statistical predictions has concerned the pickup direct interaction and Giant Quadrupole Resonance similar features. [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.

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.

The proton and deuteron induced reactions have a great interest for the assessment of induced radioactivity of accelerator components. Such data are needed for estimation of the potential radiation hazard from the accelerating cavities and beam transport elements. Continuing previous irradiation experiments on copper, we provided two short run to obtain cross-section data for 65Cu(d, p)66Cu reaction. We carried out irradiation experiments with the variable-energy cyclotron U-120M of the Nuclear Physics Institute Řež. The stacked-foil technique was utilized. Because of a relatively short half life (T1/2 = 5, 120 min) and a strong annihilation peak, we placed the 1 cm Pb plate between the irradiated sample and the gamma-ray detector to reduce the dead time. The absolute values of cross-sections were calculated from the induced activities measured by the calibrated HPGe detector. The comparison of present results with data of other authors and prediction of different libraries and model calculation is discussed.

Recent high-precision measurements α-particle elastic scattering and (α,x) reaction cross sections has motivated the extension of a previous semi-microscopic analysis for the mass-region 50

An extended analysis of the nuclear reaction mechanisms involved in the deuterons interaction with 63,65Cu is presented. First, the available elastic-scattering data analysis provided us the optical potential for reaction cross sections calculations. An increased effort has been devoted to the breakup mechanism, both the elastic breakup and the breakup fusion contributions to the different activation cross sections being carefully considered. Next, the direct reaction contributions through the one nucleon stripping reaction cross sections have been calculated. Finally, the pre-equilibrium and compound-nucleus cross-section calculation, corrected for the breakup and stripping decrease of the total reaction cross section, completed the deuteron activation cross-section analysis. The overall agreement between the measured and calculated deuteron activation cross sections proves the correctness of the nuclear mechanisms account.

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. [ABSTRACT FROM AUTHOR]

Background: Recent studies of deuteron-induced reactions around the Coulomb barrier B pointed out that numerical calculations for deuteron-induced reactions are beyond current capabilities. The statistical model of nuclear reactions was used in this respect since the compound-nucleus (CN) mechanism was considered to be responsible for most of the total-reaction cross section σR in this energy range. However, specific noncompound processes such as the breakup (BU) and direct reactions (DR) should be also considered for the deuteron-induced reactions, making them different from reactions with other incident particles. Purpose: The unitary and consistent BU and DR consideration in deuteron-induced reactions is proved to yield results at variance with the assumption of negligible noncompound components. Method: The CN fractions of σR obtained by analysis of measured neutron angular distributions in deuteron-induced reactions on 27Al, 56Fe, 63,65Cu, and 89Y target nuclei, around B, are compa/red with the results of an unitary analysis of every reaction mechanism. The latter values have been supported by the previously established agreement with all available deuteron data for 27Al, 54,56-58,natFe, 63,65,natCu and 93Nb. Results: There is a significant difference between the larger CN contributions obtained from measured neutron angular distributions and calculated results of an unitary analysis of every deuteron-interaction mechanism. The decrease of the latter values is mainly due to the BU component. Conclusions: The above-mentioned differences underline the key role of the breakup and direct reactions that should be considered explicitly in the case of deuteron-induced reactions. [ABSTRACT FROM AUTHOR]

Recent measurements of α-particle induced reactions on the 64Zn nucleus, below and around the Coulomb barrier, are analyzed simultaneously with α-particle emission at similar energies in proton-induced reactions on Zn isotopes. All open reaction channels, particularly the γ decay, are calculated using consistent input parameters. Additionally, we check a previous optical-model potential for α particles on nuclei within the mass number range 45≤A≤209 [Avrigeanu et al., Phys. Rev. C 90, 044612 (2014)] and prove its correctness in the outgoing channel at least for the present case involving 64Zn and nearby nuclei. The reliability of this potential for incident as well as emitted low-energy α particles is supported by the successful reproduction of high-precision measured data, using no empirical rescaling factor of the γ and/or particle widths. [ABSTRACT FROM AUTHOR]

The recent high-precision measurements of ɑ-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 ɑ 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 ɣ-ray strength functions, but no empirical rescaling factor of the ɣ and/or neutron widths have been involved within statistical model calculation of the corresponding (ɑ,x) reaction cross sections. [ABSTRACT FROM AUTHOR]

The activation cross sections for production of 51Cr, 52,54,56Mn, 59Fe, and 55,56,57,58Co radioisotopes in deuteron-induced reactions on natural Fe were measured at deuteron energies up to 20 MeV. Then, within an extended analysis of deuteron interactions with natFe, all processes from elastic scattering until the evaporation from fully equilibrated compound system have been taken into account. Following the available elastic-scattering data analysis that supports the deuteron optical potential for reaction cross sections calculations, increased attention is paid especially to the breakup (BU) mechanism and direct reactions (DR). The deuteron activation cross-section analysis is completed by consideration of the preequilibrium and compound-nucleus contributions, corrected for decrease of the total reaction cross section due to the leakage of the initial deuteron flux towards BU and DR processes. The overall agreement of the measured data and model calculations validates the description of nuclear mechanisms taken into account, particularly the strong effects of direct interactions that have still not been appropriately considered within previous deuteron activation evaluations. [ABSTRACT FROM AUTHOR]

The activation cross sections of (d, p), (d, 2M), (d, 2np + nd + t), (d, 2nα), and (d, pα) reactions on 93Nb were measured in the energy range from 1 to 20 MeV using the stacked-foil technique. Then, within a simultaneous analysis of elastic scattering and reaction data, the available elastic-scattering data analysis was carried out in order to obtain the optical potential for reaction cross-section calculations. Particular attention was paid to the description of the breakup mechanism and direct reaction stripping and pick-up, followed by pre-equilibrium and compound-nucleus calculations. The measured cross sections as well as all available deuteron activation data of 93Nb were compared with results of local model calculations carried out using the codes FRESCO and STAPRE-H and both default and particular predictions of the code TALYS-1.4 and TENDL-2012-evaluated data. [ABSTRACT FROM AUTHOR]

Recent accurate data obtained for the isomeric cross section of the 197Au(n, In) 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 197Au target nucleus. Thus, a definite proof of a moment of inertia equal to that of the rigid-body has been obtained for the 196Au nucleus, while indications infer about half the rigid-body for 194Ir. [ABSTRACT FROM AUTHOR]

The dominance of the deuteron breakup mechanism around the Coulomb barrier is shown by an analysis of the 231Pa(d, 3n)230U reaction excitation function, while the same attribute was found within a former assessment for the deuteron-induced fission. The present alternative result is obtained by taking into account, in addition to pre-equilibrium and compound-nucleus processes, the opposite effects of deuteron breakup, namely the decrease of the deuteron total reaction cross section, and the inelastic-breakup enhancement of various deuteron-induced reaction channels. [ABSTRACT FROM AUTHOR]

The cross sections of the 115Sn(α,γ)119Te, 115Sn(α,n)118Te, and 116Sn(α,n)119Te reactions (both on ground and isomeric states) have been measured at effective center-of-mass energies from 9.3 to 14.8 MeV. During a first experiment, enriched self-supporting 115Sn (51.2%) + 116Sn (24.4%) foils were bombarded with an α beam delivered by the Bucharest IFIN-HH Tandem Accelerator. In a second experiment, a highly enriched 116Sn target was irradiated in order to disentangle the experimental cross section contributions due to 115Sn(α,γ)119Te and 115Sn(α,n)118Te reactions obtained in the first measurement. The beam-induced activity was measured with two large volume HPGe detectors in close geometry. The experimental results were compared with theoretical predictions obtained in the framework of the statistical model. [ABSTRACT FROM AUTHOR]

Results of new cross section measurements are presented for the following neutron-induced reactions: 58Ni(n, p)58m+gCo, 58Ni(n, p)58mCo, 58Ni(n, x)57Co, 58Ni(n, 2n)57Ni, 60Ni(n, p)60m+gCo, 60Ni(n, p)60mCo, 61Ni(n, p)61Co, 61Ni(n, x)60mCo, 62Ni(n, x)61Co, and 59Co(n, 2n)58m+gCo with emphasis on incident energies between 14 and 20 MeV. In addition, new results have been obtained for the isomer ratios of the 58Ni(n, p)58m+gCo, the 60Ni(n, p)60m+gCo and 59Co(n, 2n)58m+gCo reactions.Detailed model calculations were undertaken to study the systematics of (n,xp) reactions on Ni isotopes and the use of the measured isomer ratios for the determination of the effective moment of inertia in the level density expression. Good overall agreement was obtained and, in particular, the case of the 58Ni target isotope now shows a complete physically consistent database that is ideal to test model calculations. The difference in spin between isomer and ground state of ΔJ=3 for the 58Co and 60Co residual nuclei results in a sensitivity to the spin dependence of the level density in these nuclei. However, at present, measurement uncertainties and uncertainties associated with the decay schemes preclude a definitive conclusion about the appropriate value of the effective moment of inertia. A comparison was made between a locally optimized parameter set based on all available data and a global approach. This approach allowed to identify where problems with the global approach can be expected. The locally optimized parameter set includes for the first time gamma-ray strength-functions based on an improved systematics of the gamma-ray widths. [Copyright &y& Elsevier]

Taking elastic scattering of [sup 6,8]He on protons as an example, it is shown that the differences between density distributions coming from different models can be evaluated when scattering data of the nuclei involved are available for comparison. Microscopic elasticscattering angular distributions have been calculated for incident energies <100A MeV by using the Tanihata and COSMA models for the density distributions of He nuclei, the M3Y-Paris effective NN interaction, and the Bray et al. imaginary part of the optical potential. The present microscopic angular distributions based on the Tanihata densities are in good agreement with the available experimental data and also similar to results of other theoretical calculations, showing the sensitivity of scattering to the density distributions of these helium isotopes. [ABSTRACT FROM AUTHOR]

Consistent pre-equilibrium emission and statistical model calculations of fast neutron induced reaction cross sections are used to validate nuclear level densities for excitation energies up to 40 MeV in the mass region A ≃50. A 'composed' level density approach has been employed by using the back-shifted Fermi gas model for excitation energies lower than 12 MeV and a realistic analytical formula for higher excitations. In the transition region from the BSFG model range to that of full applicability of the realistic formula, an interpolation between the predictions of the two models is adopted. The interpolation rule, suggested by microscopic level density calculations, has been validated through the comparison of the calculated and experimental cross sections. [ABSTRACT FROM AUTHOR]

Novel measurements of (α,γ) and (α,n) reaction cross sections on the target nucleus 151Eu, close to the reaction thresholds, support the choice of recently proposed parameters of the a-particle optical model potential below the Coulomb barrier. A better understanding of the a-particle optical potential at these energies leads to a statistical model analysis of additional partial cross sections that were measured but not considered within a former model analysis. On this basis we have tentatively assigned a modified Jπ=9¯ spin and parity to the 22.7-h isomer in 154Tb. [ABSTRACT FROM AUTHOR]

Background: Further studies of high-precision measurements of α-induced reaction data below the Coulomb barrier have still raised questions about the α-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 (α,x) reaction cross sections have been carried out using model parameters that were previously obtained by analyzing independent data, particularly γ-ray strength functions, and taking into account their uncertainties and questions of extrapolation for nuclei without similar data. Results: Consistent description of the recent α-induced reaction data is provided by the above-mentioned optical potential with no empirical rescaling factors of either its own parameters or the γ and/or nucleon widths. Effects of still uncertain SM parameters on calculated α-induced reaction cross sections and conclusions on the α-OMP can be now discussed due to unprecedented precision of the new data. Conclusions: The α-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. [ABSTRACT FROM AUTHOR]

Background: Challenging questions of the α-particle optical-model potential (OMP) are still pointed out by recent high-precision measurements of α-induced reaction data below the Coulomb barrier. Moreover, the reliability of a previous OMP for α particles on nuclei within the mass number range 45≤A≤209 has been recently proved for emitted α particles as well, but only in the case of proton-induced reactions on Zn isotopes [Phys. Rev. C 91, 064611 (2015) (Paper I)]. Purpose: Analysis of most recent (α,γ) reaction data for Ge and Zr isotopes, which provides an additional validation of the above-mentioned potential, is related to a further account of α-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 γ-ray strength functions, has been involved within model calculation of the (α,γ) as well as (n,α) 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 α-induced reaction data with no empirical rescaling factors of the γ 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,α) reaction cross sections. Conclusions: An optical potential with a volume imaginary component seems to be needed to describe the low-energy α-particle evaporation, while only surface absorption occurs in α-induced reactions at similar energies. [ABSTRACT FROM AUTHOR]

Comparative assessment of the total breakup proton-emission cross sections measured for 56 MeV deuteron interaction with target nuclei from 12C to 209Bi, with an empirical parametrization and recently calculated microscopic neutron-removal cross sections was done at the same time with similar data measured at 15, 25.5, 70, and 80 MeV. Comparable mass dependencies 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 was not possible because of 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. [ABSTRACT FROM AUTHOR]

Background: Recent high-precision measurements of α-induced reaction data below the Coulomb barrier have pointed out questions about the α-particle optical-model potential (OMP) which are still unanswered within various mass ranges. Purpose: The applicability of 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 γ-ray strength functions, have been involved within statistical model calculation of the (α,x) reaction cross sections. Results: The above-mentioned potential provides a consistent description of the recent α-induced reaction data with no empirical rescaling factors of the γ and/or nucleon widths. Conclusions: A suitable assessment of α-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. [ABSTRACT FROM AUTHOR]