46 results on '"Avrigeanu, V."'
Search Results
2. Validation of an optical potential for incident and emitted low-energy α-particles in the A∼60 mass range.
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Avrigeanu, V. and Avrigeanu, M.
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QUADRUPOLES , *RESONANCE , *FORECASTING , *NUCLEAR spectroscopy - Abstract
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]
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- 2021
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3. Consistent Assessment of Deuteron Interactions at Low and Medium Energies.
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Avrigeanu, M. and Avrigeanu, V.
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DEUTERON reactions , *PARTICLE emissions , *COULOMB barriers (Nuclear fusion) , *STRIPPING reaction (Nuclear physics) , *COMPOUND nucleus - Abstract
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]
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- 2019
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4. On the Physics Beyond the a-particle Optical Potential Parameters.
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Avrigeanu, V., Avrigeanu, M., and Mănăilescu, C.
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NUCLEAR optical potentials , *COULOMB barriers (Nuclear fusion) , *NUCLEAR reactions , *ALPHA rays , *NUCLEAR models , *NUCLEAR astrophysics - Abstract
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]
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- 2019
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5. Uncertainties of α-particle Optical Potential Assessment Around and Below the Coulomb Barrier.
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Avrigeanu, V., Avrigeanu, M., and Mănăilescu, C.
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COULOMB barriers (Nuclear fusion) , *NUCLEAR excitation , *PARTICLE emissions , *NUCLEAR optical models , *ASTROPHYSICS - Abstract
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]
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- 2017
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6. Enhanced ɑ-particle optical potential at low energies, for the mass range A~45-209.
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Avrigeanu, V., Avrigeanu, M., and Mănăilescu, C.
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SPECIAL relativity (Physics) , *NUCLEAR optical potentials , *NUCLEAR reactions , *NUCLEAR astrophysics , *RARE earth metals - Abstract
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]
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- 2015
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7. On Reaction Mechanisms Involved in the Deuteron-Induced Surrogate Reactions.
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Avrigeanu, M., Avrigeanu, V., and Mănăilescu, C.
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NUCLEAR reactions , *DEUTERON reactions , *PARTICLE interactions , *COULOMB barriers (Nuclear fusion) , *ACTINIDE elements - 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. [ABSTRACT FROM AUTHOR]
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- 2015
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8. Role of breakup and direct processes in deuteron-induced reactions at low energies.
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Avrigeanu, M. and Avrigeanu, V.
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COMPOUND nucleus , *DEUTERON reactions , *DIRECT reactions (Nuclear physics) , *COULOMB barriers (Nuclear fusion) , *ANGULAR distribution (Nuclear physics) - Abstract
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]
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- 2015
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9. Consistent optical potential for incident and emitted low-energy α particles.
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Avrigeanu, V. and Avrigeanu, M.
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ALPHA particle scattering , *ZINC isotopes , *COULOMB barriers (Nuclear fusion) , *PROTONS , *DECAY schemes (Radioactivity) , *NUCLEAR reactions - Abstract
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]
- Published
- 2015
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10. Further explorations of the ɑ-particle optical model potential at low energies for the mass range A ≈ 45-209.
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Avrigeanu, V., Avrigeanu, M., and Mănăilescu, C.
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NUCLEAR physics , *NUCLEAR optical models , *COULOMB barriers (Nuclear fusion) , *PARTICLES (Nuclear physics) , *PARTICLE interactions , *NUCLEAR reactions - Abstract
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]
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- 2014
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11. α-particle optical potentials for nuclear astrophysics (NA) and nuclear technology (NT).
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Avrigeanu, V. and Avrigeanu, M.
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NUCLEAR astrophysics , *PARTICLES (Nuclear physics) , *NUCLEAR optical potentials , *ELASTIC scattering , *NUCLEAR fusion - Abstract
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]
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- 2012
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12. On neutron-induced reaction mechanisms at medium energies.
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Avrigeanu, V., Avrigeanu, M., and Roman, F. L.
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NEUTRONS , *NUCLEAR reactions , *NUCLEAR cross sections , *NUCLEAR models , *INERTIA (Mechanics) - Abstract
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]
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- 2012
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13. Deuteron-induced reaction mechanisms at low energies.
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Avrigeanu, M., Avrigeanu, V., and Roman, F. L.
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DEUTERONS , *NUCLEAR reactions , *NUCLEAR cross sections , *NUCLEAR models , *EQUILIBRIUM - Abstract
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]
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- 2012
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14. Sensitivity of Activation Cross Sections of Tungsten to Nuclear Reaction Mechanisms.
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Avrigeanu, V., Eichin, R., Forrest, R. A., Freiesleben, H., Herman, M., Koning, A. J., and Seidel, K.
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TUNGSTEN , *NUCLEAR reactions , *NUCLEAR physics , *NEUTRONS , *WASTE management , *POWER plants - Abstract
In order to reduce the deviation of calculated-to-experimental activity (C/E) following benchmark experiments with pure W irradiated by 14-MeV neutrons, of interest for safety aspects and waste management of power plants, a detailed analysis of the activation cross sections was carried out using the computer codes EMPIRE-II and TALYS as well as local parameter sets within the STAPRE-H code. The sensitivity of the calculated cross sections to various model parameters is derived and discussed in connection with improving the C/E of the benchmark experiment. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]
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- 2005
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15. Low energy deuteron-induced reactions on Fe isotopes.
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Avrigeanu, M., Avrigeanu, V., Bém, P., Fischer, U., Honusek, M., Katovsky, K., Mǎnǎilescu, C., Mrázek, J., Šimečková, E., and Závorka, L.
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DEUTERON reactions , *IRON isotopes , *RADIOISOTOPES , *NUCLEAR cross sections , *DIRECT reactions (Nuclear physics) - Abstract
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]
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- 2014
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16. Low-energy deuteron-induced reactions on 93Nb.
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Avrigeanu, M., Avrigeanu, V., Bém, P., Fischer, U., Honusek, M., Koning, A. J., Mrázek, J., Simecková, E., Stefánik, M., and Závorka, L.
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DEUTERON reactions , *ACTIVATION cross sections , *ELASTIC scattering , *NUCLEAR models , *PICK-up reactions ,NIOBIUM isotopes - Abstract
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]
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- 2013
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17. Isomeric cross sections of fast-neutron-induced reactions on 197Au.
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Avrigeanu, M., Avrigeanu, V., Diakaki, M., and Vlastou, R.
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NUCLEAR cross sections , *NUCLEAR isomers , *NUCLEAR reactions , *GOLD isotopes , *NUCLEAR models , *NUCLEAR physics - Abstract
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]
- Published
- 2012
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18. Investigation of deuteron breakup and deuteron-induced fission on actinide nuclei at low incident energies.
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Avrigeanu, M., Avrigeanu, V., and Koning, A. J.
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DEUTERONS , *NUCLEAR fission , *ACTINIDE elements , *NUCLEAR energy , *COULOMB potential , *RADIOISOTOPES , *NUCLEAR excitation , *NUCLEAR cross sections - Abstract
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]
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- 2012
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19. Cross sections for α-particle induced reactions on 115,116Sn around the Coulomb barrier.
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Filipescu, D., Avrigeanu, V., Glodariu, T., Mihai, C., Bucurescu, D., Ivaşcu, M., Căta-Danil, I., Stroe, L., O.6Sima, Căta-Danil, G., Deleanu, D., Ghiţă, D. G., Mărginean, N., Mărginean, R., Negret, A., Pascu, S., Sava, T., Suliman, G., and Zamfir, N. V.
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COULOMB excitation , *NUCLEAR excitation , *NUCLEAR isomers , *DETECTORS , *NUCLEAR physics - Abstract
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]
- Published
- 2011
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20. Pre-equilibrium reactions on the stable tungsten isotopes at low energy.
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Avrigeanu, V., Chuvaev, S. V., Eichin, R., Filatenkov, A. A., Forrest, R. A., Freiesleben, H., Herman, M., Koning, A. J., and Seidel, K.
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CHROMIUM group , *PARTICLES (Nuclear physics) , *NUCLEAR reactions , *NUCLEAR physics - Abstract
Excitation functions were measured for the 180W(n,2n) 179mW, 182W(n, p) 182Ta, 182W(n, p) 182m2Ta, 182W(n, α) 179m2Hf, 183W(n, p) 183Ta, 183W(n, α) 180mHf, 184W(n, p) 184Ta, 184W(n, α) 181Hf, 186W(n, p) 186Ta, 186W(n, α) 183Hf, 186W(n, n'α) 182mHf, and 186W(n, 2n) 185W reactions from 13.4 to 14.9 MeV. The data of these reactions that are dominant for neutron-induced activation in tungsten were in most cases either defective or incomplete. The experimental results are compared with the results of calculations including all activation channels for the stable W isotopes up to a neutron incident energy of 20 MeV, using two global- and one local-parameter approaches which take into account direct reaction, pre-equilibrium emission (PE), and compound nucleus contributions. The sensitivity of the calculated cross sections to various model approaches and parameters is derived and discussed also in connection with the deviation from unity of calculated-to-experimental activity ratios from benchmark experiments with natural W irradiated by D–T fusion neutrons. The particular importance of the charged-particle emission in this atomic-mass range for PE model validation is discussed and the need for additional data for incident energies above 15 MeV is demonstrated. [Copyright &y& Elsevier]
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- 2006
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21. A systematic investigation of reaction cross sections and isomer ratios for neutrons up to 20 MeV on Ni-isotopes and 59Co by measurements with the activation technique and new model studies of the underlying reaction mechanisms
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Semkova, V., Avrigeanu, V., Glodariu, T., Koning, A.J., Plompen, A.J.M., Smith, D.L., and Sudár, S.
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CHEMICAL reactions , *NEUTRONS , *COBALT - Abstract
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 ofΔJ=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]- Published
- 2004
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22. Analysis of α-induced reactions on 151Eu below the Coulomb barrier.
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Avrigeanu, V. and Avrigeanu, M.
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COULOMB functions , *PARTICLES (Nuclear physics) , *NUCLEAR optical models , *PARITY (Physics) , *NUCLEAR isomers - Abstract
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]
- Published
- 2011
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23. Role of consistent parameter sets in an assessment of the α-particle optical potential below the Coulomb barrier.
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Avrigeanu, V. and Avrigeanu, M.
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COULOMB potential , *COULOMB barriers (Nuclear fusion) , *MEASUREMENT errors , *STATISTICAL models , *DATA analysis , *EXTRAPOLATION - Abstract
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]
- Published
- 2019
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24. Consistent optical potential for incident and emitted low-energy α particles. II. α emission in fast-neutron-induced reactions on Zr isotopes.
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Avrigeanu, V. and Avrigeanu, M.
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ZIRCONIUM , *ISOTOPES , *ALPHA rays - Abstract
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]
- Published
- 2017
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25. Additive empirical parametrization and microscopic study of deuteron breakup.
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Avrigeanu, M. and Avrigeanu, V.
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DEUTERONS , *DEUTERON reactions , *NUCLEAR physics - Abstract
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]
- Published
- 2017
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26. Analysis of uncertainties in α-particle optical-potential assessment below the Coulomb barrier.
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Avrigeanu, V. and Avrigeanu, M.
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COULOMB barriers (Nuclear fusion) , *NUCLEAR optical potentials , *NUCLEAR cross sections - Abstract
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]
- Published
- 2016
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27. The Activities of the European Consortium on Nuclear Data Development and Analysis for Fusion.
- Author
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Fischer, U., Avrigeanu, M., Avrigeanu, V., Cabellos, O., Kodeli, I., Koning, A., Konobeyev, A. Yu., Leeb, H., Rochman, D., Pereslavtsev, P., Sauvan, P., Sublet, J.-C., Trkov, A., Dupont, E., Leichtle, D., and Izquierdo, J.
- Subjects
- *
NUCLEAR fusion , *NUCLEAR counters , *DATA analysis , *NUCLEAR physics - Abstract
This paper presents an overview of the activities of the European Consortium on Nuclear Data Development and Analysis for Fusion. The Consortium combines available European expertise to provide services for the generation, maintenance, and validation of nuclear data evaluations and data files relevant for ITER, IFMIF and DEMO, as well as codes and software tools required for related nuclear calculations. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
28. Advanced breakup-nucleon enhancement of deuteron-induced reaction cross sections.
- Author
-
Avrigeanu, M., Rochman, D., Koning, A. J., Fischer, U., Leichtle, D., Costache, C., and Avrigeanu, V.
- Subjects
- *
DEUTERONS , *COMPUTER programming , *NUCLEAR reactions - Abstract
Following the EUROfusion PPPT-programme action for an advanced modeling approach of deuteron-induced reaction cross sections, as well as specific data evaluations in addition of the TENDL files, an assessment of the details and corresponding outcome for the latter option of TALYS for the breakup model has been carried out. The breakup enhancement obtained in the meantime within computer code TALYS, by using the evaluated nucleon-induced reaction data of TENDL-2019, is particularly concerned. Discussion of the corresponding results, for deuteron-induced reactions on 58 Ni, 96 Zr, and 231 Pa target nuclei up to 200 MeV incident energy, includes limitations still existing with reference to the direct-reaction account. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
29. On temperature dependence of the optical potential for alpha-particles at low energies.
- Author
-
Avrigeanu, M., von Oertzen, W., and Avrigeanu, V.
- Subjects
- *
ELASTIC scattering , *SCATTERING (Physics) , *COLLISIONS (Nuclear physics) , *DISTRIBUTION (Probability theory) - Abstract
Within the double folding formalism of the α-nucleus optical potential, used previously for a semi-microscopic analysis of the α-particle elastic scattering on A ~ 100 nuclei at energies below 32 MeV, effects due to changes of the nuclear density at a finite temperature are considered. Parameterizations of the double-folding (DF) real potential as well as of a regional phenomenological potential have been used in the study of the (n, α) reaction cross sections for the target nuclei 92,95,98,100Mo. Taking into account the microscopic DF potentials based on nuclear density distributions, we are able to fully describe the excitation functions of the (n, α) reactions. It is shown that the temperature dependence of the nuclear density distribution function can be an important aspect that has to be included in statistical model calculations even for a nuclear temperature smaller than 2 MeV. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
30. The neutrons for science facility at SPIRAL-2.
- Author
-
Ledoux, X., Aïche, M., Avrigeanu, M., Avrigeanu, V., Balanzat, E., Ban-d'Etat, B., Ban, G., Bauge, E., Bélier, G., Bém, P., Borcea, C., Caillaud, T., Chatillon, A., Czajkowski, S., Dessagne, P., Doré, D., Fischer, U., Frégeau, M. O., Grinyer, J., and Guillous, S.
- Subjects
- *
NEUTRON emission , *RADIOACTIVE wastes , *NUCLEAR energy , *TIME-of-flight measurements , *NUCLEAR reactions , *NEUTRON cross sections - Abstract
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]
- Published
- 2017
- Full Text
- View/download PDF
31. The role of nuclear data for fusion nuclear technology.
- Author
-
Fischer, U., Angelone, M., Avrigeanu, M., Avrigeanu, V., Bachmann, C., Dzysiuk, N., Fleming, M., Konobeev, A., Kodeli, I., Koning, A., Leeb, H., Leichtle, D., Ogando, F., Pereslavtsev, P., Rochman, D., Sauvan, P., and Simakov, S.
- Subjects
- *
NUCLEAR fusion , *NUCLEAR power plants , *WASTE management , *NUCLEAR facility decommissioning , *NEUTRON sources - Abstract
Abstract The role of nuclear data for neutronics analyses of Fusion Technology (FT) facilities is presented in this paper. Nuclear data evaluations of high quality are required for transport simulations, uncertainty assessments, activation and radiation damage calculations affecting the design and performance of the FT facilities, as well as safety, licensing, waste management and decommissioning issues. A corresponding programme on the nuclear data development (NDD) and qualification is conducted within the Power Plant Physics and Technology (PPPT) programme of EUROfusion supporting the development of the DEMO fusion power plant and the IFMIF-DONES neutron source. The programme builds on the achievements of pre-ceding NDD activities within the European fusion programme as addressed in the paper. Further needs for design, shielding, activation and radiation dose calculations are discussed, and recommendations are given to further improve and qualify the nuclear data base for PPPT nuclear analyses. This includes dedicated experimental activities tailored to the needs of DEMO and IFMIF-DONES. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
32. PRESENT STATUS AND FUTURE PROG RAMS OF THE n_TOF EXPERIMENT.
- Author
-
Chiaveri, E., Calviani, M., Vlachoudis, V., Weiß, C., Andriamonje, S., Andrzejewski, J., Audouin, L., Avrigeanu, V., Barbagallo, M., Bécares, V., Bečvář, F., Belloni, F., Berthoumieux, E., Billowes, J., Boccone, V., Brugger, M., Calviño1, F., Cano-Ott, D., Carrapiço, C., and Cerutti, F.
- Subjects
- *
NEUTRONS , *PROTON synchrotrons , *PROTON beams , *SPALLATION (Nuclear physics) , *NEUTRON flux - Abstract
The neutron time-of-flight facility n_TOF at CERN, Switzerland, operational since 2001, delivers neutrons using the Proton Synchrotron (PS) 20 GeV/c proton beam impinging on a lead spallation target. The facility combines a very high instantaneous neutron flux, an excellent time of flight resolution due to the distance between the experimental area and the production target (185 meters), a low intrinsic background and a wide range of neutron energies, from thermal to GeV neutrons. These characteristics provide a unique possibility to perform neutron-induced capture and fission cross-section measurements for applications in nuclear astrophysics and in nuclear reactor technology. The most relevant measurements performed up to now and foreseen for the future will be presented in this contribution. The overall efficiency of the experimental program and the range of possible measurements achievable with the construction of a second experimental area (EAR-2), vertically located 20 m on top of the n_TOF spallation target, might offer a substantial improvement in measurement sensitivities. A feasibility study of the possible realisation of the installation extension will be also presented. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
33. The Neutrons for Science Facility at SPIRAL-2.
- Author
-
Ledoux, X., Aïche, M., Avrigeanu, M., Avrigeanu, V., Audouin, L., Balanzat, E., Ban-d'Etat, B., Ban, G., Barreau, G., Bauge, E., Bélier, G., Bem, P., Blideanu, V., Blomgren, J., Borcea, C., Bouffard, S., Caillaud, T., Chatillon, A., Czajkowski, S., and Dessagne, P.
- Subjects
- *
NEUTRONS , *PARTICLE accelerators , *ION bombardment , *PHYSICAL measurements , *DEUTERONS , *RADIOACTIVE wastes , *NUCLEAR medicine , *FUSION reactors , *NUCLEAR counters - Abstract
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]
- Published
- 2011
- Full Text
- View/download PDF
34. Analysis of Deuterium Scattering on 6,7Li up to 50 MeV Based on Realistic Effective NN Interaction.
- Author
-
Avrigeanu, M., von Oertzen, W., Fischer, U., and Avrigeanu, V.
- Subjects
- *
DEUTERIUM , *HYDROGEN isotopes , *ISOTOPES , *NUCLIDES , *ELASTIC scattering , *SCATTERING (Physics) , *PHYSICS - Abstract
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]
- Published
- 2005
- Full Text
- View/download PDF
35. Optical Model Potentials for α-Particles Scattering around the Coulomb Barrier on Medium-Mass Nuclei.
- Author
-
Avrigeanu, M., von Oertzen, W., Roman, F. L., and Avrigeanu, V.
- Subjects
- *
PARTICLES , *SCATTERING (Physics) , *COLLISIONS (Nuclear physics) , *ELASTIC scattering , *NUCLEAR cross sections , *COLLISIONS (Physics) , *PARTICLES (Nuclear physics) , *NUCLEAR physics - Abstract
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]
- Published
- 2005
- Full Text
- View/download PDF
36. Average neutron parameters for hafnium
- Author
-
Noguere, G., Rich, E., De Saint Jean, C., Litaize, O., Siegler, P., and Avrigeanu, V.
- Subjects
- *
NEUTRON scattering , *HAFNIUM isotopes , *NUCLEAR energy , *NEUTRON sources , *PHYSICS literature , *NUCLEAR cross sections ,INSTITUTE for Reference Materials & Measurements (Geel, Belgium) - Abstract
Abstract: The neutron transmission of natural hafnium samples have been measured within the 2 eV to 50 keV energy range at the white neutron source GELINA of the Institute for Reference Materials and Measurements (IRMM) in Geel, Belgium. Data sets for two temperatures (77 K and 300 K) and three sample thicknesses (1 mm, 2 mm, 15 mm) have been simultaneously analyzed in terms of Reich–Moore parameters. The ESTIMA technique in association with the generalized SPRT method were used to obtain a consistent set of l-dependent average resonance parameters. For each hafnium isotope, scattering radius , neutron strength function , distant level parameter , mean level spacing and average radiation width are given and compared with results reported in the literature. The capture and total cross sections calculated by the CONRAD code using this set of average parameters were successfully compared to experimental data retrieved from EXFOR. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
37. Complementary optical-potential analysis of -particle elastic scattering and induced reactions at low energies
- Author
-
Avrigeanu, M., Obreja, A.C., Roman, F.L., Avrigeanu, V., and von Oertzen, W.
- Subjects
- *
ELASTIC scattering , *SCATTERING (Physics) , *COLLISIONS (Nuclear physics) , *DEUTERON scattering - Abstract
Abstract: A previously derived semi-microscopic analysis based on the Double Folding Model, for -particle elastic scattering on nuclei at energies below 32MeV, is extended to medium mass nuclei and energies from ∼13 to 50MeV. 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 -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 , , and reaction cross sections considered target nuclei from 45Sc to 118Sn and incident energies below ∼12MeV. The former diffuseness of the real part of optical potential as well as the surface imaginary potential depth have been found to be responsible for the actual difficulties in the description of these data, and modified in order to obtain an optical potential which describes equally well both the low-energy elastic scattering and induced reaction data for -particles. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
38. Analysis of deuteron elastic scattering and induced activation cross-sections of light and medium nuclei for IFMIF EVEDA
- Author
-
Avrigeanu, M., von Oertzen, W., Forrest, R.A., Obreja, A.C., Roman, F.L., and Avrigeanu, V.
- Subjects
- *
DEUTERON scattering , *ELASTIC scattering , *NUCLEAR cross sections , *PARTICLE accelerator design & construction , *ENGINEERING design , *PROTON spectra , *NUCLEAR reactions , *NUCLEAR energy - Abstract
Abstract: An extended analysis has been performed of elastic-scattering and reaction cross-sections of deuterons on the nucleus, for deuteron energies from 3 to 60MeV, based on a semi-microscopic optical potential with a double-folding real part and phenomenological imaginary and spin-orbit terms. An increased effort is devoted to the breakup mechanism, the analysis of proton-emission spectra and angular distributions from deuteron-induced reactions on nuclei from Al to Pb, at incident energies from 15 to 80MeV, providing the energy- and mass-dependence of the breakup mechanism contribution. The corresponding direct-reaction cross-sections within the same energy range has then been analyzed, the improved description of both the elastic-scattering and reaction measured data backing the proper use of these optical potentials for deuteron activation assessment. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
39. Fast-neutron induced pre-equilibrium reactions on 55Mn and 63,65Cu at energies up to 40 MeV.
- Author
-
Avrigeanu, M., Chuvaev, S. V., Filatenkov, A. A., Forrest, R. A., Herman, M., Koning, A. J., Plompen, A. J. M., Roman, F. L., and Avrigeanu, V.
- Subjects
- *
STABLE isotopes , *NEUTRONS , *MANGANESE , *COPPER - Abstract
The experimental cross sections for all neutron-induced reactions on the stable isotopes of Mn and Cu at incident energies up to 40 MeV are compared with results of pre-equilibrium (PE) and statistical model calculations. Taking advantage of the large sensitivity of statistical model analysis to residual nuclei parameters, for energies up to 20 MeV, our work was then focused on assessing PE model assumptions by data analysis in the energy range 20–40 MeV. The PE model reliance on the nuclear potential finite-depth correction for description of particle–hole state densities (PSD), nuclear-shell effects within the PSD formula, and single-particle level density is thus discussed with regard to the whole data basis. The related variance of the model results has been found as large as the differences between the global and local model calculations, while the data basis available between 20 and 40 MeV for the Mn and Cu isotopes is however too scarce in this respect. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
40. Analysis of deuteron elastic scattering on 6,7Li up to 50 MeV
- Author
-
Avrigeanu, M., von Oertzen, W., Fischer, U., and Avrigeanu, V.
- Subjects
- *
SCATTERING (Physics) , *PHYSICS , *NUCLEAR energy , *ANALOG resonance - Abstract
Abstract: An analysis of the elastic scattering of deuterons on 6,7Li, for energies up to 50 MeV, has been carried out by using a phenomenological optical potential. Energy-dependent average parameters of the optical model potential have been obtained in the analysis of the corresponding real and imaginary volume integrals, pointing out an “anomalous” behavior of the real potential when the imaginary part approaches zero. This could be a consequence of the dispersion relations, but may be also related to the non-locality of the basic real potential term which introduces a slow and smooth energy dependence. On the other hand, the coupled reaction channels method has been used in order to describe the experimental angular distributions including the backward hemisphere at 14.7 and 19.6 MeV but not at 50 MeV. The comparison between the experimental and calculated elastic scattering angular distributions proves the reliability of the present average optical potentials, at variance with the extrapolation of the deuteron global potentials to other mass and energy domains. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
41. Optical model potentials for <f>α</f>-particles scattering around the Coulomb barrier on <f>A∼100</f> nuclei
- Author
-
Avrigeanu, M., von Oertzen, W., Plompen, A.J.M., and Avrigeanu, V.
- Subjects
- *
CELL nuclei , *LOW energy electron diffraction - Abstract
The double-folding formalism of the
α -nucleus optical potential is used and appropriate effective nucleon–nucleon(NN) interaction andα -particle density distribution at low energies are obtained by analysis of theα –α elastic-scattering at energies below 35 MeV. Next a semi-microscopic analysis based on the Double Folding Model (DFM) for theα -particle elastic scattering onA∼100 nuclei at energies below 32 MeV has been carried out. The energy-dependent phenomenological imaginary part for this semi-microscopic optical model potential (OMP) was obtained, making use also of the dispersive correction to the microscopic real potential. This imaginary potential has then been introduced within a complete phenomenological analysis of the same data basis. A regional parameter set of the phenomenological OMP for low-energyα -particles has thus been obtained for nuclei in the mass rangeA∼100 , which is of interest to basic nuclear physics as well as nuclear technology. [Copyright &y& Elsevier]- Published
- 2003
- Full Text
- View/download PDF
42. Measurement of the natMo(n,x)94Nb cross section using ultra low-level γ-ray spectrometry at HADES.
- Author
-
Reimer, P., Hult, M., Plompen, A. J. M., Johnston, P. N., Avrigeanu, V., and Qaim, S. M.
- Subjects
- *
NUCLEAR cross sections , *MOLYBDENUM , *GAMMA ray spectrometry , *NIOBIUM - Abstract
The cross section for the natMo(n, x)94Nb reaction was measured in the energy range from 14.5 to 20.3 MeV using both conventional γ-rayspectrometry and the ultra low-level γ-ray spectrometry (ULGS) facility in the underground laboratory HADES. The exceptionally long half-life of the activation product 94Nb of 20300 years required a long irradiation, a large sample and a special irradiation geometry, to allow a simultaneous determination of the three data points. This measurement presents the first data above 14 MeV. The data are well described by model calculations with the STAPRE-H code that include the 94Mo(n, p)94Nb and 95Mo(n, np)94Nb reactions. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
- View/download PDF
43. Elastic Scattering as a Test of Density Distributions in [sup 6]He and [sup 8]He.
- Author
-
Avrigeanu, M., Anagnostatos, G. S., Antonov, A. N., and Avrigeanu, V.
- Subjects
- *
ELASTIC scattering , *NUCLEAR reactions , *HELIUM - Abstract
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]
- Published
- 2002
- Full Text
- View/download PDF
44. Measurements of 59Co(d,p) 60m,gCo, 51V(d,p)52V, and natV(d,xn) 51Cr cross sections in the 2.7-5.4-MeV energy range.
- Author
-
Kreisel, A., Weissman, L., Cohen, A., Hirsh, T., Shor, A., Aviv, O., Eliyahu, I., Avrigeanu, M., and Avrigeanu, V.
- Subjects
- *
MEASUREMENT , *CHROMIUM - Abstract
The cross sections of the 59Co(d,p) 60m,gCo, 51V (d,p) 52V, and natV (d,xn)51 Cr reactions were accurately measured at the Soreq Applied Research Accelerator Facility in the energy range 2.7-5.4 MeV. The obtained results together with other data, available in the same region of the nuclear chart, were used for verifying the theoretical models. The consistent theoretical model calculation successfully reproduces the experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
45. Consistent account of deuteron-induced reactions on nat Cr up to 60 MeV.
- Author
-
Šimečková, E., Avrigeanu, M., Fischer, U., Mrázek, J., Novak, J., Štefánik, M., Costache, C., and Avrigeanu, V.
- Subjects
- *
DEUTERON reactions , *DIRECT reactions (Nuclear physics) , *NUCLEAR cross sections - Abstract
Background: Specific noncompound processes such as breakup (BU) and distinct direct reactions (DR) make deuteron-induced reactions different from reactions with other incident particles. Significant discrepancies with measured cross sections were caused by taking into account only the pre-equilibrium emission (PE) and compound-nucleus (CN) mechanisms while microscopic calculation of inclusive BU and DR cross sections is still investigated numerically. Thus, reaction cross sections recommended most recently for high-priority elements are still based on data fit. 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 a 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 γ spectrometry using the 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 a fully equilibrated compound system, but with 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 a suitable BU and DR assessment is completed by 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. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
46. Deuteron-induced reactions on Ni isotopes up to 60 MeV.
- Author
-
Avrigeanu, M., Šimečková, E., Fischer, U., Mrázek, J., Novak, J., Štefánik, M., Costache, C., and Avrigeanu, V.
- Subjects
- *
DEUTERON reactions , *NICKEL isotopes , *BINDING energy - Abstract
Background: The high complexity of the deuteron-nucleus interaction from the deuteron weak binding energy of 2.224 MeV is also related to a variety of reactions induced by the deuteron-breakup (BU) nucleons. Thus, specific noncompound processes as BU and direct reactions (DR) make the deuteron-induced reactions so different from reactions with other incident particles. The scarce consideration of only pre-equilibrium emission (PE) and compound-nucleus (CN) mechanisms led to significant discrepancies with experimental results so that recommended reaction cross sections of high-priority elements as, e.g., Ni have mainly been obtained by fit of the data. Purpose: The unitary and consistent BU and DR account in deuteron-induced reactions on natural nickel may take advantage of an extended database for this element, including new accurate measurements of particular reaction cross sections. Method: The activation cross sections of 64,61,60Cu, 65,57Ni, and 55,56,57,58,58m,60Co nuclei for deuterons incident on natural Ni at energies up to 20 MeV, were measured by the stacked-foil technique and high-resolution gamma spectrometry using U-120M cyclotron of CANAM, NPI CAS. Then, within an extended analysis of deuteron interactions with Ni isotopes up to 60 MeV, all processes from elastic scattering until the evaporation from fully equilibrated compound system have been taken into account while an increased attention is paid especially to the BU and DR mechanisms. Results: The deuteron activation cross-section analysis, completed by consideration of the PE and CN contributions corrected for decrease of the total-reaction cross section from the leakage of the initial deuteron flux towards BU and DR processes, is proved satisfactory for the first time to all available data. Conclusions: The overall agreement of the measured data and model calculations validates the description of nuclear mechanisms taken into account for deuteron-induced reactions on Ni, particularly the BU and DR that should be considered explicitly. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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