EXFOR Database Research Articles

High-resolution measurements of the exited states (n,pn), (n,dn) C-12 cross sections

Measurements of C12 cross sections for the excited states (n,p 0 ) up to (n,p 4 ) and (n,d 0 ), (n,d 1 ) have been carried out. The Van de Graaff neutron generator of the EC-JRC-IRMM laboratory has been used for these measurements. A very thin tritiated target (263 μg/cm 2 ) was employed with deuteron beams energies impinging on the target in the range 2.5–4.0 MeV. Neutrons in the range 18.9–20.7 MeV were produced with an intrinsic energy spread of 0.2–0.25% FWHM. With such narrow neutron energy spread, using a high energy resolution device such as a single crystal diamond detector, several peaks from the outgoing charged particles produced by the (n,p n ), (n,d n ) and also (n,α 0 ) reactions appear in the pulse height spectrum. The peaks can be identified using the reaction Q-values. The diamond detector used for these measurements has shown an intrinsic energy resolution lower than 0.9% FWHM. The analysis of the peaks has permitted to derive the partial carbon reaction cross sections for several excited states. The results are presented in this paper with the associated uncertainties and they are compared with different versions of TENDL compilation when these data are available (e.g. versions 2009, 2010, 2011 and 2015) and also with experimental results available in the EXFOR database.

EXFOR – a global experimental nuclear reaction data repository: Status and new developments

Members of the International Network of Nuclear Reaction Data Centres (NRDC) have collaborated since the 1960s on the worldwide collection, compilation and dissemination of experimental nuclear reaction data. New publications are systematically complied, and all agreed data assembled and incorporated within the EXFOR database. Recent upgrades to achieve greater completeness of the contents are described, along with reviews and adjustments of the compilation rules for specific types of data.

Determination of the effects of nuclear level density parameters on photofission cross sections of 235U up to 20 MeV

The level density models and level density parameters are two of important quantities for describing the properties of nuclei. Especially, the level density parameter has an important role as input in calculation of reaction cross sections. In this study, the cross sections on 235 U(g,f) reaction were calculated for different level density models using the TALYS 1.6 code up to 20 MeV gamma incident energies. First, it was determined the level density model that was the closest to the experimental data. Secondly, cross sections obtained for different level density parameters of this model were compared with experimental data from the EXFOR database. Thus it was determined the best level density parameter fit to experimental data.

The (α,n) reaction cross-section calculations for some isotopes of iron group elements in the range of 5-20 MeV

Iron group elements (Sc, Mn, Fe, Co, Ni) are especially very important because structural material selection in design of fusion–fission reactors is very crucial. Obtained results from the nuclear reactions using structural materials can be used developing for these structural materials some isotopes. For this reason, in this study the cross sections of 45 Sc(α,n)48 V, 55 Mn(α,n)58 Co, 54 Fe(α,n)57 Ni, 59 Co(α,n)62 Cu, 62 Ni(α,n)65 Zn reactions have been calculated at 5-20 MeV energy ranges by using TALYS 1.8 and NON-SMOKER codes. Obtained results were compared experimental data from EXFOR database.

Nuclear data activities at the n_TOF facility at CERN

Nuclear data in general, and neutron-induced reaction cross sections in particular, are important for a wide variety of research fields. They play a key role in the safety and criticality assessment of nuclear technology, not only for existing power reactors but also for radiation dosimetry, medical applications, the transmutation of nuclear waste, accelerator-driven systems, fuel cycle investigations and future reactor systems as in Generation IV. Applications of nuclear data are also related to research fields as the study of nuclear level densities and stellar nucleosynthesis. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. Experimental nuclear reaction data are compiled on a worldwide basis by the international network of Nuclear Reaction Data Centres (NRDC) in the EXFOR database. The EXFOR database forms an important link between nuclear data measurements and the evaluated data libraries. CERN's neutron time-of-flight facility n_TOF has produced a considerable amount of experimental data since it has become fully operational with the start of the scientific measurement programme in 2001. While for a long period a single measurement station (EAR1) located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2) in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at CERN's neutron time-of-flight facility n_TOF will be presented.

Evolving landscape of low-energy nuclear physics publications

Evolution of low-energy nuclear physics publications over the last 120 years has been analyzed using nuclear physics databases. An extensive study of Nuclear Science References, Experimental Nuclear Reaction Data (EXFOR), and Evaluated Nuclear Structure Data File (ENSDF) contents provides a unique picture of refereed and non-refereed nuclear physics references. Significant fractional contributions of non-refereed reports, private communications and conference proceedings in EXFOR and ENSDF databases in the 1970's reflect extensive experimental campaigns and an insufficient number of research journals. This trend has been reversed in recent years because the number of measurements is much lower, while number of journals is higher. In addition, nuclear physics results are mainly published in a limited number of journals, such as Physical Review C and Nuclear Physics A. In the present work, historic publication trends and averages have been extracted and analyzed using nuclear data mining techniques. The results of this study and implications are discussed and conclusions presented.

Analysis of isomeric ratios for medium-mass nuclei

Values of the isomeric ratios for product nuclei originating from simple charge-exchange reactions were analyzed. The cross sections for the formation of product nuclei in ground and isomeric states were calculated with the aid of the TALYS 1.4 and EMPIRE 3.2 codes. The calculated values of the isomeric ratios were compared with their experimental counterparts taken from the EXFOR database. For the 86,87Y, 94,95,96,99Tc, and 44Sc nuclei, the experimental values of the isomeric ratios exceed the respective calculated values. The nuclei in question feature weak deformations and have high-spin yrast lines and rotational bands. The possible reason behind the discrepancy between theoretical and experimental isomeric ratios is that the decay of yrast states leads with a high probability to the formation of isomeric states of detected product nuclei.

Cross Section Calculations of (n,2n) and (n,p) Nuclear Reactions on Germanium Isotopes at 14–15 MeV

Neutron incident reaction cross sections of Germanium isotopes (70,72,74,76Ge) were investigated for the (n,2n) and (n,p) reactions around 14–15 MeV. Cross section calculations have been presented for 70Ge(n,2n)69Ge, 72Ge(n,2n)71Ge, 74Ge(n,2n)73Ge, 76Ge(n,2n)75Ge, 70Ge(n,p)70Ga, 72Ge(n,p)72Ga, 74Ge(n,p)74Ga, and 76Ge(n,p)76Ga reactions. Theoretical calculations were performed with four different computer codes: ALICE/ASH for the Geometry Dependent Hybrid model, TALYS 1.6 for two component Exciton model, EMPIRE 3.2 Malta for Exciton model and PCROSS for Full Exciton model with the incident neutron energy up to 20 MeV. The (n,2n) and (n,p) reaction cross section calculations were compared with empirical formulas derived by several researchers and compared with the experimental data obtained from EXFOR database as well as with evaluated Nuclear data files (ENDF/B-VII.1: USA 2014). Results show good agreement between the theoretical calculations having a major importance in nuclear data evaluation calculations and the experimental data from literature.

Calculation of Cross-sections and Astrophysical S-Factors for 62Ni(α,n) and 62Ni(α,γ) Reactions of Structural Fusion Material Nickel

Nickel is an important element in fusion reactor technologies and astrophysical applications. Therefore, the knowledge of astrophysical S-factors and cross-sections on nickel isotopes is needed. In this work, the cross sections of the 62Ni(α,n) and 62Ni(α,γ) reactions have been calculated. The alpha capture cross sections was calculated up to 10 MeV. In these theoretical calculations, the TALYS 1.6 and NON-SMOKER codes were used. Also for the 62Ni(α,n) and 62Ni(α,γ) reactions, we calculated the astrophysical S-factors that determine the probability of reaction in low energies. Results of our calculations were checked to the experimental data obtained from EXFOR database.

Theoretical investigation of cross sections and astrophysical S-factors for the92Mo(α,n)95Ru and94Mo(α,n)97Ru reactions

Molybdenum is commonly applied as a constructive material in different types of nuclear reactors. The cross sections of the 92 Mo(α,n)95 Ru and 94 Mo(α,n)97 Ru reactions have been calculated at 5-20 MeV energy ranges. In theoretical calculations, the TALYS1.6 and NONSMOKER codes were used. Also the astrophysical S-factors were calculated. Results of our calculations were checked to the experimental data obtained from EXFOR database.

Discussion of isomeric ratios in (p, n) and (d, 2n) reaction

Isomeric ratios (IR) in the (p, n) and (d, 2n) reactions are considered. The dependence of IR values on the projectile type and energy, the target- and product-nucleus spin, the spin difference between the isomeric and ground states of products, and the product mass number is discussed. The isomeric ratios for 46 product nuclei (from 44m,gSc to 127m,gXe) obtained in reactions where target and product nuclei have identical mass numbers were calculated at energies from the reaction threshold to 50 MeV (with a step of ΔE = 1 MeV). The calculations in question were performed with the aid of the TALYS 1.4 code package. The calculated IR values were compared with their experimental counterparts available from the literature (EXFOR database). In the majority of cases, the calculated IR values agree well with the experimental data in question. It is noteworthy that the IR values obtained in (d, 2n) reactions are substantially greater than those in (p, n) reactions.

Comparison of Level Density Models for the 60,61,62,64Ni(p, n) Reactions of Structural Fusion Material Nickel from Threshold to 30 MeV

The knowledge of level density for reaction cross-section calculations are needed for various applications such as fission and fusion reactor design, accelerator driven sub-critical systems, nuclear medicine, neutron capture and astrophysics. In this study, the excitation functions for (p, n) reactions from reaction threshold to 30 MeV proton incident energy on 60Ni, 61Ni, 62Ni and 64Ni isotopes were calculated using TALYS 1.6 nuclear code involving the level density models. This is of importance to the validation of nuclear model approaches with increased predictive power. There are several models of level density that can be used to predict cross-section. In this work, the (p, n) cross-sections would be calculated using three different model of level density, such as constant temperature model, back-shifted fermi gas model and generalized superfluid model on 60,61,62,64Ni reactions. The (p, n) reaction cross-section calculations for 60,61,62,64Ni target nuclei were compared with each other and the experimental nuclear reaction data obtained from EXFOR database.

Cross Section Calculations of Neutron Induced Reactions on 124,126,128,134,136Xe

In the nuclear energy applications Xenon is a desirable material because of its high molecular weight and inert nature. The cross section calculations of 124Xe(n,2n)123Xe, 126Xe(n,2n)125Xe, 128Xe(n,2n)127Xe, 134Xe(n,2n)133Xe and 136Xe(n,2n)135Xe reactions were performed by ALICE/ASH (with Weisskopf-Ewing equilibrium model), TALYS 1.6 (with two component exciton model suggested by Kalbach) and EMPIRE 3.2 Malta (with exciton model recommended by Clinev and Ribansky) nuclear reaction codes. In addition, semi-empirical cross section formula of Tel et al. was used to obtain cross sections at 14–15 MeV energy. Obtained results were compared to available experimental data by EXFOR database and TENDL-2013 data.

Neutron Production Cross-Section and Geant4 Calculations of the Structural Fusion Material 59Co for (α,xn) and (γ,xn) Reactions

Recent advances in technology and computer sciences give us simplicity to investigate phenomena of nuclear physics. Scientists have improved various nuclear reaction codes such as Talys, Alice/ASH, Cem95, Empire, Geant4 and Fluka. These programs give us chance to calculate crucial quantity like reaction cross-section, energy spectrum of out-going particles, stopping power and penetrating distances in target material. The stopping power of alpha in 59Co material is acquired as it has helpful applications of shielding and choosing the proper thickness of the target. Evaluation of the reaction cross-section data is very important to various applications such as improvement structural material, reactor design and radioisotopes production. In this study, we calculated the neutron production cross-sections of 59Co using TALYS 1.6 and EMPIRE 3.1 codes for different level density models. Penetrating distances and stopping powers have been calculated for the alpha particles taking into consideration all possible reactions in 59Co using GEANT4 simulation program. The obtained (α,xn) and (γ,xn) reactions (x = 1, 2, 3) cross-section values have been compared with the each other and against the experimental nuclear reaction data existing in EXFOR database.

(γ, 2n)-Reaction cross-section calculations of several even-even lanthanide nuclei using different level density models

There are several level density models that can be used to predict photo-neutron cross sections. Some of them are Constant Temperature + Fermi Gas Model (CTFGM), Back-Shifted Fermi Gas Model (BSFM), Generalized Superfluid Model (GSM), Hartree-Fock-Bogoliubov microscopic Model (HFBM). In this study, the theoretical photo-neutron cross sections produced by (γ, 2n) reactions for several eveneven lanthanide nuclei such as 140,142Ce, 142,144,146,148,150Nd, 144,148,150,152,154Sm, and 160Gd have been calculated on the different level density models as mentioned above by using TALYS 1.6 and EMPIRE 3.1 computer codes for incident photon energies up to 30 MeV. The obtained results have been compared with each other and available experimental data existing in the EXFOR database. Generally, at least one level density model cross-section calculations are in agreement with the experimental results for all reactions except 144Sm(γ, 2n)142Sm along the incident photon energy, TALYS 1.6 BSFM option for the level density model cross-section calculations can be chosen if the experimental data are not available or are improbable to be produced due to the experimental difficulty.

Calculation of cross-sections and astrophysical s-factors for the63Cu(α,n) and63Cu(α,γ) reactions

The cross sections and astrophysical S-factors of the 63 Cu(α,γ) and 63 Cu(α,n) reactions have been calculated. The radiative alpha capture reaction cross sections was calculated in the incident energy range of 3 to 10 MeV and the (α,n) reaction cross sections was calculated in the incident energy range of 7 and 16 MeV. In these theoretical calculations, the TALYS 1.6 and NON-SMOKER codes were used. Also for these reactions, it was calculated the astrophysical S-factors which describe the possibility of reaction in low energies. Obtained results were compared to the experimental data taken from EXFOR database.

Investigation of the effects of nuclear level density parameters on the cross sections for the234U(γ,f) reaction

In this study, we have investigated the effects of nuclear level density parameters on the cross sections for the ^234U(gamma,f) reaction up to 20 MeV. The cross sections on ^234U(gamma,f) reaction were calculated for different level density models using the TALYS 1.6 code. First, it was determined the level density model that was the closest to the experimental data. Secondly, cross sections obtained for different level density parameters of this model were compared with experimental data from the EXFOR database. Thus it was determined the best level density parameter fit to experimental data.

Cross-section studies of relativistic deuteron reactions on copper by activation method

The cross-sections of relativistic deuteron reactions on natural copper were studied in detail by means of activation method. The copper foils were irradiated during experiments with the model spallation targets in the Joint Institute for Nuclear Research. The irradiation of activation samples was performed by beams in the energy range from 1 to 8GeV. Residual nuclides were measured by the gamma spectrometry. While the EXFOR database contains sets of data for relativistic proton reactions, data for deuteron reactions in this energy range are almost missing. Lack of such experimental cross-section values prevents the use of copper foils from beam integral monitoring. For this reason our experiments focused on their measurement and completely new data were obtained in the energy region where no experimental data have been available so far. The copper monitors with their low sensitivity to fast neutrons will contribute to improvement of the beam integral determination during accelerator-driven system studies.

Reaction Cross-Section, Stopping Power and Penetrating Distance Calculations for the Structural Fusion Material 54Fe in Different Reactions

Nuclear reaction codes give us simplicity to investigate phenomena of nuclear physics. There have many computer programs such as TALYS, EMPIRE, ALICE/ASH, PCROSS, FLUKA and GEANT4. The stopping power of alpha, deuteron, proton and triton in 54Fe materials is acquired as it has helpful applications of shielding and choosing the proper thickness of the target. Level density is very important to understanding nuclear reaction mechanism. The knowledge of level density for reaction cross-section calculations are required for various application such as astrophysics, accelerator driven sub-critical systems, nuclear medicine, fission and fusion reactor design and neutron capture. In this study, we calculated the cross-sections of 54Fe using TALYS 1.6 and EMPIRE 3.1 codes for different reactions through the four level density models. Stopping powers and penetrating distances were calculated for the alpha, deuteron, proton and triton particles, taking into consideration all possible reactions in 54Fe for incident energies of 1–45 MeV using GEANT4 calculation code. The obtained reaction cross-section results have been compared with the each other and against the experimental nuclear reaction data existing in EXFOR database.

Photo-neutron cross-section calculations of 142,143,144,145,146,150Nd rare-earth isotopes for (γ, n) reaction

The theoretical photo-neutron cross sections for (γ, n) reaction have been calculated on 142,143,144,145,146,150Nd rare-earth isotopes at photon energies of 8–23 MeV using the PCROSS, TALYS 1.2, and EMPIRE 3.1 computer codes. TALYS 1.2 two-component exciton model and EMPIRE 3.1 exciton model has been used to calculate the pre-equilibrium photo-neutron cross sections. PCROSS Weisskopf-Ewing model has been used for the reaction equilibrium cross-section calculations. The obtained cross sections have been compared with each other and against the experimental values existing in the EXFOR database. Generally, pre-equilibrium model cross-section calculations are in good agreement with the experimental data for all reactions along the incident photon energy in this study.