Search

We have systematically studied the level density parameter, nuclear level density and decay width of neutron and fission of superheavy nuclei. This paper is validated by comparing with available experiments for 2 3 6 U and 2 4 0 Pu. The angular dependence of level density parameter, level densities and ratio of Γ n and Γ f the thermal excitation energy (U) have been studied in the superheavy region 1 0 4 ≤ Z ≤ 1 1 8. The role of entrance channel parameter on decay width of neutron and fission has been studied both in cold and hot fusion reactions in the superheavy region 1 0 4 ≤ Z ≤ 1 1 8. Systematic variation of Γ n and Γ f is observed in both the cases. Finally, predicted Γ n / Γ tot for the synthesis of superheavy nuclei Z = 1 1 9 and 120. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The nuclear level density parameter is an important quantity in nuclear physics. Nuclear level density parameter has been calculated using different methods. In this work at first, the single particle level density has been calculated by LDA method, then the nuclear level density parameter has been obtained as a function of temperature. Based on Lestone method and using Thomas-Fermi approximation, the level density parameter has been calculated to the order of next to Lestone results (corrected Lestone method). Using calculated nuclear level density parameter and taking into account the pairing energy, the nuclear level density, excitation energy, entropy and heat capacity have been calculated

For a sustainable nuclear energy program using fission reactors, the reduction or elimination of long-lived radioactive waste is essential. The hazardous Long-Lived Fission Products (LLFP), which are by-products of the operation of nuclear reactors, need to be converted to short-lived or stable nuclei. For nuclear transmutation, the knowledge of reaction cross-sections is important. The cross-section and half-life for the proton-induced transmutation of the LLFP, 1 2 6 Sn, produced as nuclear waste from the reactor have been calculated. The cross-section for the (p,n) reaction on unstable 1 2 6 Sn has been calculated using phenomenological as well as microscopic models of optical potentials and level densities in the framework of the statistical nuclear model using the latest version of the code TALYS-1.96. The Koning–Delaroche (KD) and Jeukenne–Lejeune–Mahaux–Bruyeres (JLMB) optical models, as well as back-shifted Fermi gas model (BFM) and Hartree–Fock (HF) level density, based on the Skyrme force from Gorielys tables, have been used. The renormalized optical model parameters and level density models obtained by comparing cross-sections with data for protons incident on stable 1 1 2 , 1 1 4 , 1 1 5 , 1 1 6 , 1 1 7 , 1 1 8 , 1 1 9 , 1 2 0 , 1 2 2 , 1 2 4 Sn isotopes were extended to make a prediction of (p,n) cross-section on unstable 1 2 6 Sn isotope. The excitation function obtained using JLMB-HF calculation for 1 2 6 Sn reveals a peak at an incident proton energy of 8.5 MeV with a corresponding cross-section of 269 mb. It would be of interest to perform experiments for measurements of cross-section where data are unavailable, especially in the peak regions and beyond, to validate the predictions of this work. It is found that for a proton flux of 6. 2 5 × 1 0 1 4 s − 1 cm − 2 , and a peak cross-section calculated using JLMB-HF calculation, the effective half-life of transmutation of 1 2 6 Sn is about 65 years, thus justifying its feasibility. [ABSTRACT FROM AUTHOR]

In this study, reaction cross-section calculations of some proton-induced reactions on natPd have been investigated under the effects of level density models. All calculations involving level density models have been done employing the TALYS code's 1.95 version. TALYS is an opensource software. It gives foresight to the researchers about many parameters of a desired nuclear reaction, one of which is known as cross-section, when it is not possible to perform it due to specific reasons. The TALYS 1.95 code consists of six different level density models, which have all been included in this study. All obtained cross-section results gathered from the utilization of level density models have been compared with available experimental data. The mentioned available experimental data used in this study have been obtained from the International Experimental Nuclear Reaction Data Library (EXFOR) database. A graphical representation of generated calculation results, and available experimental data have been displayed for these comparisons. These graphical representations are also used to point out the most consistent level density model with respect to the experimental data for each reaction investigated in this study. The use of level density models was found to affect the results of cross-sectional calculations. [ABSTRACT FROM AUTHOR]

Level density ρ is derived for a finite system with strongly interacting nucleons at a given energy E, neutron N, and proton Z particle numbers, projection of the angular momentum M, and other integrals of motion, within the semiclassical periodic-orbit theory (POT) beyond the standard Fermi-gas saddle-point method. For large particle numbers, one obtains an analytical expression for the level density which is extended to low excitation energies U in the statistical micro-macroscopic approach (MMA). The interparticle interaction averaged over particle numbers is taken into account in terms of the extended Thomas - Fermi component of the POT. The shell structure of spherical and deformed nuclei is taken into account in the level density by the Strutinsky shell correction method through the mean-field approach used near the Fermi energy surface. The MMA expressions for the level density ρ reaches the well-known macroscopic Fermi-gas asymptote for large excitation energies U and the finite combinatoric power-expansion limit for low energies U. We compare our MMA results for the averaged level density with the experimental data obtained from the known excitation energy spectra by using the sample method under statistical and plateau conditions. Fitting the MMA ρ to these experimental data on the averaged level density by using only one free physical parameter - inverse level density parameter K - for several nuclei and their long isotope chain at low excitation energies U one obtains the results for K. These values of K might be much larger than those deduced from neutron resonances. The shell, isotopic asymmetry, and pairing effects are significant for low excitation energies.

Level density P is derived for a finite system with strongly interacting nucleons at a given energy E, neutron N and proton Z particle numbers, projection of the angular momentum M, and other integrals of motion, within the semiclassical periodic-orbit theory (POT) beyond the standard Fermi-gas saddle-point method. For large particle numbers, one obtains an analytical expression for the level density which is extended to low excitation energies U in the statistical micro-macroscopic approach (MMA). The interparticle interaction averaged over particle numbers is taken into account in terms of the extended Thomas - Fermi component of the POT. The shell structure of spherical and deformed nuclei is taken into account in the level density by the Strutinsky shell correction method through the mean-field approach used near the Fermi energy surface. The MMA expressions for the level density P reaches the well-known macroscopic Fermi-gas asymptote for large excitation energies U and the finite combinatoric power-expansion limit for low energies U. We compare our MMA results for the averaged level density with the experimental data obtained from the known excitation energy spectra by using the sample method under statistical and plateau conditions. Fitting the MMA P to these experimental data on the averaged level density by using only one free physical parameter – inverse level density parameter K – for several nuclei and their long isotope chain at low excitation energies U, one obtains the results for K. These values of K might be much larger than those deduced from neutron resonances. The shell, isotopic asymmetry, and pairing effects are significant for low excitation energies. [ABSTRACT FROM AUTHOR]

In neutron star merger events, the occurrence of rapid neutron capture process (r-process) has been established. About half of the elements beyond iron are synthesised in stars by r-process. In stellar environments, very high neutron flux in a short time (∼ a few seconds) can be attained, leading to the creation of progressively neutron-rich nuclei until the waiting point is reached. At this point, further neutron capture reactions cannot happen and highly neutron-rich nuclei become stable via β - decay. A detailed understanding of the r-process remains illusive. In the present work, the theoretical predictions of radiative neutron capture (n, γ ) cross-sections of astrophysical importance and the reaction rates using the Hauser–Feshbach statistical model formalism have been investigated for Fe, Co, Ni, Cu, Zn, Ga, Ge, As and Se isotopes (around the first r-process peak near mass = 80 ). These calculations have been compared with the JINA REACLIB reaction rates. The inherent uncertainties remain large in neutron-rich nuclei. When there is low-energy enhancement, a significant increase in the reaction rate occurs for neutron capture. [ABSTRACT FROM AUTHOR]

Nuclear level density parameter is one of the fundamental quantities required for finding the nuclear level density. The most essential ingredient for the theoretical analysis of nuclear reactions is nuclear level density. This work is a theoretical study on the variation of collective nuclear level density parameter of certain even-even actinides. This calculations were performed by using phenomenological models of level density. The computational code TALYS 1.9 has been made use of for this purpose. Here, we calculated the collective nuclear level density parameter of 268 - 278 Th, 270 - 280 U, 272 - 282 Pu, 274 - 284 Cm, 278 - 288 Cf, 278 - 288 Fm and 280 - 290 No, at neutron separation energy. Variation of collective level density parameter with different mass number is estimated for these selected nuclei. These studies show that nuclear level density parameter is minimum at neutron number N = 180 and 184 for these systems studied. Apart from that, the level density parameters decrease towards N = 184 . [ABSTRACT FROM AUTHOR]

Level density ρ (E , Q) is derived within the micro-macroscopic approximation (MMA) for a system of strongly interacting Fermi particles with the energy E and additional integrals of motion Q, in line with several topics of the universal and fruitful activity of A. S. Davydov. Within the extended Thomas Fermi and semiclassical periodic orbit theory beyond the Fermi-gas saddle-point method, we obtain ρ ∝ I ν (S) / S ν , where Iν (S) is the modified Bessel function of the entropy S. For small shell-structure contribution, one finds ν = κ/2 + 1, where κ is the number of additional integrals of motion. This integer number is a dimension of Q, Q = {N, Z, ...} for the case of two-component atomic nuclei, where N and Z are the numbers of neutrons and protons, respectively. For much larger shell structure contributions, one obtains ν = κ /2 + 2. The MMA level density ρ reaches the well-known Fermi gas asymptote for large excitation energies and the finite micro-canonical combinatoric limit for low excitation energies. The additional integrals of motion can also be the projection of the angular momentum of a nuclear system for nuclear rotations of deformed nuclei, number of excitons for collective dynamics, and so on. Fitting the MMA total level density ρ(E, Q) for a set of the integrals of motion Q = {N, Z}, to experimental data on a long nuclear isotope chain for low excitation energies, one obtains the results for the inverse level-density parameter K, which differs significantly from those of neutron resonances due to shell, isotopic asymmetry, and pairing effects. [ABSTRACT FROM AUTHOR]

The production cross section of various isotopes of Og superheavy nucleus through cold reactions of 84 Kr + 208 Pb , 86 Kr + 208 Pb and 88 Kr + 208 Pb is calculated based on the di-nuclear system (DNS) model using double-folding and proximity potentials. Due to the lack of experimental data, two 70 Zn + 208 Pb and 70 Zn + 209 Bi reactions are studied also for comparison. The calculated formation cross sections of Og, SHN using two potentials are compared with each other as well as experimental data. The exact Ginzburg–Landau (EGL) theory is applied in order to obtain the temperature of produced 292 Og , 294 Og , 296 Og , 278 Nh and 277 Cn superheavy isotopes. Analyzing of entire calculated results revealed that the obtained formation cross sections using double-folding potential are consistent with the available experimental data compared with the results of proximity potential. [ABSTRACT FROM AUTHOR]

The excitation functions of 63Cu(p,n)63Zn, 65Cu(p,n)65Zn, 66Zn(p,n)66Ga, 67Zn(p,n)67Ga and 68Zn(p,n)68Ga reactions were computed using the TALYS-1.95 computer code from reaction threshold to 40 MeV energy to yield medically important radioisotopes. The influence of varying level density and effective imaginary potential on reaction cross-section has been investigated. Thus, investigated results have been discussed and compared with previously available experimental data. The analysis of the cross-sections at the maximum value of energy for different reactions exhibits that the (p,n) reaction is the most commonly occurring process. The results so obtained have been found in fair agreement with measured data within error bar limits. The compound and pre-compound nuclear reaction mechanisms have also been analyzed and found very significant for validation of the nuclear model with improved accuracy level. [ABSTRACT FROM AUTHOR]

Ericson’s formula describes the partial level density (PLD) of pre-equilibrium reactions. PLD with pairing correction can be calculated by modifying Ericson’s formula using four methods, namely, pairing, improved pairing, exact Pauli and back shift energy corrections. The variations in the PLD values of each of the four formulas of strontium (88Sr), Yttrium (89Y) and Zirconium (90Zr) isotones have been calculated. Results showed that the PLD values that uses pairing and improved pairing corrections do not vary for different isotones. However, a small change in PLD values was observed when exact Pauli correction and back shift energycorrection were utilised. The change in the PLD values using back shift energy correction was bigger than the values obtained using exact Pauli correction. Therefore, the use of back shift formula is recommended in nuclear cross-section calculations because it results in noticeable changes with any small increase in mass number. [ABSTRACT FROM AUTHOR]

We examined the (p,x), (α,x), and (n,x)reaction cross sections, for the destruction of the long-lived exotic 99Tc nuclide, which is in spent fuels of nuclear power plants and radioactive waste released from hospitals. The cross sections were calculated based on different models of nuclear level density and radiative gamma strength function. We found that there is a large uncertainty in the calculated cross sections, which is up to one order of magnitude, due to the difference in the theoretical models. The (p,n), (α,n), and (n,γ)reactions have large cross sections, which are about hundreds of millibarn. Hence, these reactions are suggested for the 99Tc transmutation. To examine the reliability of the models, the calculated cross sections were compared to evaluated data in the ENDF database. The results indicate that although all the models are consistent with the ENDF data, the Constant-temperature Fermi Gas and Kopecky–Uhl Generalized Lorentzian models are the most reliable models for the investigated reactions of 99Tc. The present study is useful for better transmutation of the radioactive waste and understanding of the dependence of the cross section on the nuclear level density and gamma strength function.

Level density ρ (E , N , Z) is derived for a nuclear system with a given energy E , neutron N , and proton Z particle numbers, within the semiclassical extended Thomas–Fermi and periodic-orbit theory beyond the Fermi-gas saddle-point method. We obtain ρ ∝ I ν (S) / S ν , where I ν (S) is the modified Bessel function of the entropy S , and ν is related to the number of integrals of motion, except for the energy E. For small shell structure contribution one obtains within the micro–macroscopic approximation (MMA) the value of ν = 2 for ρ (E , N , Z). In the opposite case of much larger shell structure contributions one finds a larger value of ν = 3. The MMA level density ρ reaches the well-known Fermi gas asymptote for large excitation energies, and the finite micro-canonical limit for low excitation energies. Fitting the MMA ρ (E , N , Z) to experimental data on a long isotope chain for low excitation energies, due mainly to the shell effects, one obtains results for the inverse level density parameter K , which differs significantly from that of neutron resonances. [ABSTRACT FROM AUTHOR]

Evropiyum; ince süperiletken yapıların üretilmesi, televizyon ve monitörlerde renklerin elde edilmesi, biyomedikal uygulamalar, brakiterapi ve nükleer reaktör kontrol çubukları gibi farklı alanlarda kullanılan lantanit grubu bir metaldir. Bu çalışmada; deneysel verilere ulaşmanın mümkün olmadığı durumlarda kullanılmak amacıyla geliştirilmiş teorik nükleer reaksiyon modelleri kullanılarak, 151,153Eu izotoplarının (p,n) ve (p,3n) reaksiyonlarındaki tesir kesiti hesaplamaları gerçekleştirilmiştir. Tesir kesiti; deneysel olarak ölçülebileceği gibi, bunun mümkün olmadığı durumlarda teorik olarak da hesaplanabilmektedir ve en basit şekilde bir reaksiyonun meydana gelme olasılığını ifade eden değer olarak tanımlanabilir. Hesaplamalar; farklı teorik modellerin kullanılabilmesi amacıyla geliştirilmiş olan bilgisayar destekli TALYS 1.8 ve EMPIRE 3.2 kodlarında denge ve denge-öncesi modeller seçilerek gerçekleştirilmiştir. Deneysel veriler ile en uyumlu sonuçları üreten model, göreli varyans analizi ile tespit edilmiştir ve farklı seviye yoğunluğu modellerinin hesaplamalara etkileri araştırılmıştır. Elde edilen teorik hesaplama sonuçları, Uluslararası Deneysel Nükleer Veri Kütüphanesi (EXFOR) veri tabanından alınan deneysel veriler ve TENDL 2017 veri tabanından alınan teorik değerler ile karşılaştırılmıştır.

Özet: Optiksel model, nükleer reaksiyonları açıklamak için geliştirilen modellerden birisidir. Soğurma etkilerinin var olması halinde elastik saçılmayı genel bir yolla inceleyebilmemizi sağlar. Optiksel model potansiyeli; bileşik ve denge-öncesi nükleer reaksiyonların tesir kesitlerinin açılan reaksiyon kanallarına nasıl dağılacağını belirlediğinden dolayı, nükleeer reaksiyonlar için oldukça önemlidir. Optiksel model potansiyeli ile birlikte; seviye yoğunluğu bilgisi, tesir kesiti, enerji spektrumu ve diğer gözlenebilir nükleer reaksiyon değerlerinin güvenilir teorik analizi için belki de en önemli bileşendir. Bu çalışmada, 181Ta(α,n)184Re, 181Ta(α,2n)183Re, 181Ta(α,3n)182Re ve 181Ta(α,4n)181Re reaksiyon tesir kesitleri farklı seviye yoğunluğu ve optiksel modeller kullanılarak hesaplanmıştır. Hesaplamalarda optiksel modeller için, Watanabe düzeltmeli Koning-Delaroche, McFadden- Satchler, Demetriou-Grama-Goriely ve Avrigeanu modelleri, seviye yoğunluğu modelleri için Sabit Sıcaklık Fermi Gaz, Geri Kaydırmalı Fermi Gaz ve Genelleştirilmiş Süper Akışkan modelleri kullanılmıştır. Tüm hesaplamalar TALYS 1.8 kodu ile gerçekleştirilmiştir. Elde edilen sonuçlar Uluslararası Deneysel Nükleer Reaksiyon Data Merkezi (EXFOR)’dan alınan verilerle karşılaştırılmıştır. Hesaplamaların deneysel verilerle karşılaştırılmasında göreli varyans analizi kullanılmıştır.

In this work, we calculate the level density parameter for several nuclei by deploying the semiclassical trace formula for spherically symmetric harmonic oscillator potential with spin-orbit interactions, which describes the quantum shell effects in terms of the classical periodic orbits. With the usage of recently proposed Laplace like formula of level density parameter by Canbula et al., the effects of collective rotations and vibrations as well as deformations in nuclei are incorporated. The comparison of our results with the experimental ones show a good agreement. Later on, the study is also extended to the calculation of nuclear level density and survival probability in several superheavy nuclei (SHN). [ABSTRACT FROM AUTHOR]

Statistical fluctuations of nuclear energy spectra for the isobar A = 68 were examined by means of the random matrix theory together with the nuclear shell model. The isobar A = 68 nuclei are suggested to consist of an inert core of 56Ni with 12 nucleons in f5p-space (2p3/2, 1f5/2 and 2p1/2 orbitals). The nuclear excitation energies, required by this work, were obtained through performing f5p-shell model calculations using the isospin formalism f5pvh interaction with realistic single particle energies. All calculations of the present study were conducted using the OXBASH code. The calculated level densities were found to have a Gaussian shape. The distributions of level spacing P(s) and Δ3 statistic for the considered classes of states, obtained with full Hamiltonian of f5pvh (absence of the off-diagonal Hamiltonian) calculations, showed a chaotic (regular) behavior and coincided well with the distribution of Gaussian orthogonal ensemble (Poisson). Moreover, these distributions were independent of spin ( J ) and isospin (T ). [ABSTRACT FROM AUTHOR]

An evaluation of thermal neutron capture on the stable tungsten isotopes is presented, with preliminary results for the compound systems 183;184;185;187W. The evaluation procedure compares the g-ray cross-section data collected at the Budapest reactor, with Monte Carlo simulations of g-ray emission following the thermal neutron-capture process. The statistical-decay code DICEBOX was used for the Monte Carlo simulations. The evaluation yields new gamma rays in 185W and the confirmation of spins in 187W, raising the number of levels below which the level schemes are considered complete, thus increasing the number of levels that can be used in neutron data libraries.

We demonstrate that pairing phase transition (superfluid to normal) can be described quite generally in terms of the thermodynamical properties after verifying the obtained level densities with the available experimental data for 1 1 8 , 1 2 2 S n - isotopes. Periodic-orbit theory conveniently connects the oscillatory part of level density to the underlying classical periodic orbits and hence, leads to the shell effects in the single-particle level density. Such methods incorporated with pairing effects can be used effectively to study the phase transitions in S n -isotopes. In addition to this, an interplay between pairing correlations and the shell effects has been understood by analyzing the results obtained for the critical temperatures and shell structure energies for 1 0 2 − 1 3 8 S n isotopes. A relation between variation in critical temperatures caused by shell effects and the shell structure energies determined with and without pairing effects has been established. Furthermore, the systematics of the heat capacity (giving a clear signature of pairing phase transition) as function of temperature for these nuclei are investigated as well. [ABSTRACT FROM AUTHOR]

Level density models have an undeniable importance for a better perception on the nature of nuclear reactions, which influences our life via various ways. Many novel and advanced medical application use radioisotopes, which are produced with nuclear reactions. By considering the connection between the level density models and the importance of theoretical calculations for the production routes of medically important isotopes, this study is performed to investigate the level density model effects on the production cross-section calculations of 6 2 Zn, 6 8 Ga, 7 7 Kr, 1 0 3 Pd, 1 1 1 In, 1 2 4 I and 2 1 1 At radioisotopes via some alpha particle induced and neutron emitting reactions. For theoretical calculations; frequently used computation tools, such as TALYS and EMPIRE codes, are applied. Obtained theoretical results are then compared with the experimental data, taken from Experimental Nuclear Reaction Data (EXFOR) library. For a better interpretation of the results, a mean weighted deviation calculation for each investigated reaction is performed in addition to a visual comparison of the graphical representations of the outcomes. [ABSTRACT FROM AUTHOR]

The accurate knowledge of the nuclear level density is crucial for understanding the nuclear structure and for numerous applications including astrophysical reactions. In this review paper, we discuss the shell-model description of the nuclear level density, the use of the statistical moments method and underlying physics. The level density found with the moments method is shown to agree with the results of the exact diagonalization of the Hamiltonian matrix. The statistical approach is also compared to other standard methods for deriving level densities. The role of specific interaction matrix elements is reviewed in connection to the behavior of the level densities as these evolve. Chaotization and thermalization processes, collective enhancement and phase transitions are discussed with changing strengths of specific groups of two-body interaction matrix elements. The popular phenomenological constant temperature model is compared to the moments method and the effective temperature parameter of the model for different isotopes is discussed. [ABSTRACT FROM AUTHOR]

The temperature dependence of the recently synthesized superheavy nucleus Z = 117 is extensively studied through the statistical model for a wide range of isotopes. The model code is developed and executed for calculating the excitation energy, single neutron separation energy, level density, and entropy for the hot system. The possible sub-magic and magic numbers predicted are 178, 184, and 196. It is found that the pairing correlation collapses at T = 0.8 MeV and shell effect vanishes at T = 2.5 MeV. The limiting temperature is determined from the behavior of the level density parameter as a function of temperature. [ABSTRACT FROM AUTHOR]

Zirconium-based alloys have been widely used as structural material in the nuclear reactors. The cross-sectional values of 90Zr(n,p)90Y, 94Zr(n,p)94Y, 94Zr(n,α)91Sr and 96Zr(n,2n)95Zr nuclear reactions at this paper were calculated by EMPIRE-3.2, ALICE-ASH and TALYS-1.8 computer codes. The calculations were compared with the experimental values from the literature. [ABSTRACT FROM AUTHOR]

The excitation function of the alpha particle-induced reactions on 237Np and 238Pu has been determined for the incident alpha energies ranging from threshold to 50 MeV using TALYS1.95 nuclear reaction code. In this study, the excitation function of (α , x n) reactions on 237Np and 238Pu has been determined by invoking the Jeukenne–Lejeune–Mahaux–Bruyeres Optical model potential. The microscopic nuclear level density from Hilaire's combinatorial table is used to calculate the nuclear level density. Also, the excitation function has been evaluated by using the alpha potential of Watanabe folding approach with Koning–Delaroche spherical optical model potential and McFadden–Satchler potential. Furthermore, all the calculated cross-sections have been compared with the experimental results taken from EXFOR and the available evaluated cross-sections from TENDL2019 nuclear data library. The calculated cross sections using Jeukenne–Lejeune–Mahaux–Bruyeres Optical model potential together with microscopic nuclear level density from Hilaire's combinatorial table incorporating the Skyrme–Hartree–Fock–Bogoliubov calculation results in good correspondence with the experimental values from EXFOR. • Alpha induced cross section on 237Np and 238Pu determined using TALYS1.95. • Jeukenne-Lejeune-Mahaux model with suitable renormalization is used for computation. • Watanabe alpha potential and McFadden-Satchler alpha potential used for calculation. • The microscopic Skyrme-Hartree-Fock-Bogoliubov table used as nuclear level density. • The nuclear model analysis provides details of the best models for the calculation.. [ABSTRACT FROM AUTHOR]

A well-established knowledge of nuclear phenomena including fission, reaction cross sections, and structure/decay properties is critical for applications ranging from the design of new reactors to nonproliferation to the production of radioisotopes for the diagnosis and treatment of illness. However, the lack of a well-quantified, predictive theoretical capability means that most nuclear observables must be measured directly and used to calibrate empirical models, which in turn provide the data needed for these applications. In many cases, either there is a lack of data needed to guide the models or the results of the different measurements are discrepant, leading to the development of evaluation methodologies to provide recommended values and uncertainties. In this review, we describe the nuclear data evaluation process and the international community that carries it out. We then discuss new measurements and improved theory and/or modeling needed to address future challenges in applied nuclear science. [ABSTRACT FROM AUTHOR]

Excitation functions based on level density were calculated for proton-induced on yttrium-89 using the TALYS-1.8 code. Hence, production cross-section of the 89Y(p,x)86,88,89gZr, 86g,87g,88gY, 85gSr, and 84gRb were computed up to 50 MeV. In this study, the constant temperature model alongside the Fermi Gas model (CGCM) was employed as a default model. For this reason, the a-parameter as an essential parameter in the Fermi Gas formula was modified to obtain the best result. Besides, the Back-shifted Fermi Gas Model (BSFGM) and the Generalized Superfluid Model (GSM) are presented to the deliberation. The outcomes of cross-sections were compared with the experimental data approaching regarding desired consequences. • Cross-section of the 89Y(p,x)86,88,89gZr, 86g,87g,88gY, 85gSr, and 84gRb were computed up to 50 MeV. • Excitation functions based on level density were calculated for proton-induced on yttrium-89 using the TALYS-1.8 code. • The constant temperature model alongside the Fermi Gas model (CGCM) was employed as a default model. [ABSTRACT FROM AUTHOR]

Aims of this work are: (i) Investigation of the production of some radioisotopes that could be used in nuclear battery technology with neutron-induced reaction processes, (ii) Estimation of the cross-section curves of (n , γ) reactions for astrophysical processes in the energy region between 1 eV and 1 MeV, (iii) Determination of suitable level density models for the (n , γ) reaction processes. Additionally, the obtained results were compared with the experimental data and recommended data. Based on the calculated results, to eliminate lack of nuclear data in the literature, we recommend new experiments for some reaction processes to be performed by the experimenters. Moreover, for the (n , γ) reaction processes, suitable level density models were proposed. [ABSTRACT FROM AUTHOR]

The rapid-neutron capture process (r process) is identified as the producer of about 50% of elements heavier than iron. This process requires an astrophysical environment with an extremely high neutron flux over a short amount of time (∼ seconds), creating very neutron-rich nuclei that are subsequently transformed to stable nuclei via β − decay. In 2017, one site for the r process was confirmed: the advanced LIGO and advanced Virgo detectors observed two neutron stars merging, and immediate follow-up measurements of the electromagnetic transients demonstrated an "afterglow" over a broad range of frequencies fully consistent with the expected signal of an r process taking place. Although neutron-star mergers are now known to be r -process element factories, contributions from other sites are still possible, and a comprehensive understanding and description of the r process is still lacking. One key ingredient to large-scale r -process reaction networks is radiative neutron-capture (n , γ) rates, for which there exist virtually no data for extremely neutron-rich nuclei involved in the r process. Due to the current status of nuclear-reaction theory and our poor understanding of basic nuclear properties such as level densities and average γ -decay strengths, theoretically estimated (n , γ) rates may vary by orders of magnitude and represent a major source of uncertainty in any nuclear-reaction network calculation of r -process abundances. In this review, we discuss new approaches to provide information on neutron-capture cross sections and reaction rates relevant to the r process. In particular, we focus on indirect, experimental techniques to measure radiative neutron-capture rates. While direct measurements are not available at present, but could possibly be realized in the future, the indirect approaches present a first step towards constraining neutron-capture rates of importance to the r process. [ABSTRACT FROM AUTHOR]

A theoretical study of nuclear level density of Thorium nuclei that exist on and off the beta-stability line is carried out using Talys 1.6. The level density parameter a and spin cut-off factor σ for Thorium isotopes 2 1 6 − 2 7 0 Th are estimated. The values of both these parameters decrease towards the neutron drip line and the proton drip line. Cross-sections for (n , p) and (n , α) reactions for Thorium isotopes are also calculated. The estimated and experimental values of cross-sections for 2 3 2 Th are comparable. These evaluated data are useful in understanding the mechanism of nuclear reactions taking place under extreme conditions including those in nucleosynthesis. [ABSTRACT FROM AUTHOR]

The level density parameter a is calculated using the semi classical approach for 270110,278112, and 290116 superheavy isotopes. The Woods-Saxon potential is considered for the interaction of nucleons inside a nucleus. Thermal properties of these isotopes, including the entropy, the nuclear temperature, and the heat capacity are calculated within the framework of microcanonical ensemble and the back-shifted Fermi gas model with one adjustable parameter E1. The process of breaking the first Cooper pair and cooling of the 270110,278112, and290116 superheavy isotopes have also been observed. [ABSTRACT FROM AUTHOR]

Abstract Scientists have been focused on fusion reactor studies to overcome the increasing energy demand. The materials, which have the potential to be used in fusion reactors must be resistant to the harmful effects of radiation in the manner of material itself. Selection of the appropriate materials to be used in nuclear reactors has a crucial importance to achieve the maximum efficiency and security. Ti, V, Ni and Cu are known as some of the constructional fusion materials. Existence of many knowledge about those materials provides countless advantages to the researchers and one of them is the cross–section, which basically means the probability of a nuclear reaction's occurrence. In addition to the cross–section, there exist some other parameters, which could be pointed as gamma strength function and level density models that affect the theoretical calculations. In this study, photon induced reaction cross–sections of 46,50Ti, 51V, 58Ni and 63Cu target isotopes have been calculated by using TALYS 1.8 code with different gamma strength functions in the giant dipole resonance region. For gamma strength functions Kopecky-Uhl generalised Lorentzian Model, Brink-Axel Lorentzian Model, Hartree-Fock BCS tables, Hartree-Fock-Bogolyubov tables and Goriely's Hybrid Model have been employed. To appoint the best gamma strength function model, the relative variance calculations have been performed. Also, reaction cross–sections have been recalculated by using the best gamma strength function models through the different level density options. Constant Temperature Fermi Gas Model, Back Shifted Fermi Gas Model and Generalised Super Fluid Model have been employed for level density calculations. Experimental data for the investigated reactions have been taken from EXFOR library and used for comparisons of the obtained calculation results. Highlights • Reaction cross–section calculations have been done for 46,50Ti, 51V, 58Ni and 63Cu isotopes. • Gamma strength functions and level density models effects on cross–section calculations have been investigated. • TALYS 1.8 code has been used in the calculations. • The models are validated using the experimental values from the literature. [ABSTRACT FROM AUTHOR]

Abstract Production of radioisotopes that used in medical diagnosis and treatment are mostly based on the nuclear reactions. The cross–section data are important to understand nuclear reaction mechanisms. In this study TALYS 1.8 code has been used to calculate production cross–sections of 201Pb, 111In, 18F and 11C radioisotopes at proton induced reactions. Constant Temperature Fermi Gas Model (CTFGM), Back Shifted Fermi Gas Model (BSFGM) and Generalised Super Fluid Model (GSM) have been employed as a level density models for computations. Relative variance calculations have been carried out to determine the best level density model. In addition to cross–section calculations, total activities of radioisotopes have been presented. Production cross–section calculation results have been compared with experimental data taken from Experimental Nuclear Reaction Database (EXFOR). Highlights • Production cross–section calculations have been done for 201Pb, 111In, 18F and 11C radioisotopes. • Level density models have been used for computations. • Total activities of radioisotopes have been presented. • TALYS 1.8 code has been used in the calculations. • The models are validated using the experimental values from the literature. [ABSTRACT FROM AUTHOR]