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Öğe alpha-decay half-life calculations of superheayy nuclei using artificial neural networks(IOP PUBLISHING LTD, 2014) Bayram, Tuncay; Akkoyun, Serkan; Kara, S. Okan; Vagenas, EC; Vlachos, DSInvestigations of superheavy elements (SHE) have received much attention in the last two decades, due to the successful syntheses of SHE. In particular, alpha-decay of SHEs has a great importance because most synthesized SHE have alpha-decay and the experimentalists have evaluated the theoretical predictions of the alpha-decay half-life during the experimental design. Because of this, the correct prediction of alpha-decay half-life is important to investigate superheavy nuclei as well as heavy nuclei. In this work, artificial neural networks (ANN) have been employed on experimental alpha-decay half-lives of superheavy nuclei. Statistical modeling of alpha-decay half-life of superheavy nuclei have been found as to be successful.Öğe An analysis of E(5) shape phase transitions in Cr isotopes with covariant density functional theory(IOP PUBLISHING LTD, 2013) Bayram, Tuncay; Akkoyun, SerkanConstrained relativistic mean field theory (RMF) has been employed for analysis of the shape phase transitions of even-even Cr52-66 isotopes. The systematic investigation of ground-state shape evolution between spherical U(5) and gamma-unstable O(6) for these nuclei has been carried out by using the potential energy curves (PECs) obtained from the effective interactions NL3*, TM1, PK1 and DD-ME2. The calculated PECs have indicated that Cr-58 can be a candidate for the critical-point nucleus with E(5) symmetry. A similar conclusion is also drawn from the calculated single-particle spectra of Cr-58 and is supported by the experimental data via observed ratios of the excitation energies. Furthermore, the gamma-independent character of Cr-58 has been pointed out by using its binding energy map in the beta-gamma plane obtained from the triaxial RMF calculations, in agreement with the condition of E(5) symmetry.Öğe An approach to adjustment of relativistic mean field model parameters(E D P SCIENCES, 2017) Bayram, Tuncay; Akkoyun, Serkan; Plompen, A; Hambsch, FJ; Schillebeeckx, P; Mondelaers, W; Heyse, J; Kopecky, S; Siegler, P; Oberstedt, SThe Relativistic Mean Field (RMF) model with a small number of adjusted parameters is powerful tool for correct predictions of various ground-state nuclear properties of nuclei. Its success for describing nuclear properties of nuclei is directly related with adjustment of its parameters by using experimental data. In the present study, the Artificial Neural Network (ANN) method which mimics brain functionality has been employed for improvement of the RMF model parameters. In particular, the understanding capability of the ANN method for relations between the RMF model parameters and their predictions for binding energies (BEs) of Ni-58 and Pb-208 have been found in agreement with the literature values.Öğe Energy level and half-life determinations from photonuclear reaction on Ga target(WORLD SCIENTIFIC PUBL CO PTE LTD, 2016) Akkoyun, Serkan; Bayram, Tuncay; Dulger, Fatih; Dapo, Haris; Boztosun, IsmailPhotonuclear reactions are important tools in the understanding of the nucleus. These reactions are also interesting for realizing the element creation processes in stellar environment. The use of bremsstrahlung photons generated from clinic linear accelerator is practical for performing these type of reactions. In this study, the bremsstrahlung photons with endpoint energy of 18 MeV have been used for activating gallium target material. After irradiation, the transition energies and half-lives associated with the decay of Ga-68, Ga-70 and Ga-72 isotopes have been determined The values obtained for half-life of Ga-68, Ga-70 and Ga-72 isotopes are 67.5 +/- 0.9 min, 21.1 +/- 0.9 min and 13.8 +/- 0.4 h, respectively. It has been seen that the values are consistent with the present literature values. In addition, the new measurements of gamma-ray energies for transition energies have been obtained comparable to the literature values with good uncertainties.Öğe Estimations of beta-decay energies through the nuclidic chart by using neural network(PERGAMON-ELSEVIER SCIENCE LTD, 2014) Akkoyun, Serkan; Bayram, Tuncay; Turker, TugbaOne of the main characteristics of unstable nuclei is beta-decay energy (Q(beta)). It is determined by different methods such as beta endpoint measurements, counting in coincidence with annihilation radiation, electron capture (EC)/beta(+) ratio method, method of gamma absorption with X-ray coincidence. Beta-decay energy is a roughly linear function of atomic and mass numbers. Due to the fact that artificial neural network (ANN) is sufficient for nonlinear function approximation, in this study by using the nuclear masses from Hartree-Fock-BCS method, Q(beta) values have been obtained by ANN. It is seen that the estimations of the ANN are consistent with the calculated data within some deviation. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Estimations of fission barrier heights for Ra, Ac, Rf and Db nuclei by neural networks(WORLD SCIENTIFIC PUBL CO PTE LTD, 2014) Akkoyun, Serkan; Bayram, TuncayAccurate information about the fission barrier is important for studying of the fission process. Fission barrier is needed for discovering the island of stability in superheavy region and searching of the superheavy elements. Furthermore, the astrophysical r-process is closely related to the fission barrier of the neutron-rich nuclei. In this study, by using artificial neural network (ANN) method, we have estimated the fission barrier heights of the Rf, Db, Ra and Ac nuclei covering 230 isotopes. For inner barrier calculation, we have used Rf and Db nuclei and the barrier heights have been determined between nearly 1 MeV and 7 MeV. The related mean square error value has been obtained as 0.108 MeV. For outer barrier calculation, we have used Ra and Ac nuclei and the heights have been determined between nearly 8 MeV and 28 MeV. The related mean square error has been obtained as 0.407. The results of this study indicate that ANN is capable for the estimations of inner and outer fission barrier heights.Öğe Generation of fusion and fusion-evaporation reaction cross-sections by two-step machine learning methods(Elsevier, 2024) Akkoyun, Serkan; Yesilkanat, Cafer Mert; Bayram, TuncayIn order to obtain cross-sections of heavy-ion fusion and fusion-evaporation reactions, artificial neural networks, cubist, random forest, support vector regression, extreme gradient boosting, and multiple linear regression machine learning approaches were used separately in this study. The outcomes from these different methods that are obtained from the training carried out with the existing experimental data in the literature were compared. Furthermore, it has been observed that a two-step process yielded better results for determining the heavy ion reaction cross-sections, after first estimating which approach would be better for which reaction. In this manner, the method for which the cross-section needs to be calculated is determined by the machine learning classification application, and predictions can be made using the machine learning regression application with the determined method. It has been concluded that the obtained results are in harmony with the experimental data and that the methods can be used safely. The obtained results are published on a web page that allows for online calculation of heavy-ion fusion and fusion-evaporation reaction cross-sections.Öğe HALF-LIVES OF Sc-47 ISOTOPE FROM PHOTONUCLEAR REACTIONS(RAD ASSOC, 2016) Akkoyun, Serkan; Kocak, Gokhan; Bayram, Tuncay; Ristic, GIn order to understand atomic nuclei, photonuclear reaction is an important tool. Photons are used to induce the reactions. The use of bremsstrahlung photons generated from a medical linear accelerator is practical for performing these types of reactions. In this study, the 18 MeV endpoint energy bremsstrahlung photons have been used for activating a titanium target. By analyzing the gamma spectrum, the half-life of the Sc-47 isotope has been determined to be 3.5626 days. The result is very close to the present literature values of 3.3492 days.Öğe THE IMPOSSIBILITY OF PRODUCING I-131 FROM ITS DAUGHTER Xe-131 BY PHOTONUCLEAR REACTIONS(RAD ASSOC, 2016) Bayram, Tuncay; Akkoyun, Serkan; Celik, Necati; Haciislamoglu, Emel; Uruk, Serhat; Senturk, Sevki; Ristic, GI-131 is one of the radioisotopes in nuclear medicine procedures for diagnostic and treatment purposes. It decays to Xe-131 by emitting beta particles. In this study, we have investigated the reproduction possibility of I-131 from Xe-131 by using different reactions, including a photonuclear reaction step. We have used TALYS computer program for calculating cross-sections of the reactions. It was seen that it was not an easy task to reproduce I-131 from its decay product Xe-131 because of low reaction cross-section values. According to the results, we have seen that the calculations are in harmony with the TENDL 2014 database.Öğe Investigation of Nuclear Structures of Self-conjugate Zn, Ge, Se, Kr, Sr Nuclei(2020) Akkoyun, Serkan; Bayram, TuncayThe nuclear structure of the atomic nuclei can be theoretically investigated by using the nuclear shell model. Generally, a doubly closed-shell nucleus has been considered as inert core and the nucleons outside the core are taken into account in the calculation. It is assumed that the nucleons in the inert core do not move but each valence nucleon out of the core moves under an average potential created by the others. The self-conjugate (N=Z) medium mass nuclei region is one of the regions for the investigation of several phenomena because of the maximum spatial overlap of neutrons and protons. In this study, the structures of the medium mass N=Z nuclei have been analyzed in the scope of the nuclear shell model by using KSHELLcomputer code. In the calculations, doubly magic 56Ni were taken as core, and the 2p3/2, 1f5/2ve 2p1/2 single-particle orbits were used as valence orbits. Different two-body interactions (jun45and f5pvh) have been taken into account. The results have been compared with each other and the available values existing in the literature.Öğe Machine learning predictions for cross-sections of 43,44Sc radioisotope production by alpha-induced reactions on Ca target(Elsevier, 2024) Akkoyun, Serkan; Yesilkanat, Cafer Mert; Bayram, Tuncay43,44Sc radioisotopes are an alternative to 18F in positron emission tomography. 43,44Sc radioisotopes, which can be generated at low costs by irradiating inexpensive natural Ca with alpha particles, can be produced, and distributed in a central cyclotron facility due to their relatively long half-lives. Since there is limited experimental data on the cross-sections in the literature, in this study, cross-section predictions of the production of 43,44Sc radioisotopes with alpha particles on Ca target were carried out with different machine learning approaches. In order to improve the results, the feature engineering method was applied to the variables of the cross-section predictions. Moreover, predictions have been improved with Stacked Ensemble Learning (SEL) approaches, a complex methodology that leverages the predictive capabilities of multiple underlying models to build a higherlevel metamodel. We found that the best results were obtained with Bayesian Regularized Neural Network, Support Vector Regression and Stacked Ensemble Learning methods.Öğe Neural network predictions of (n,2n) reaction cross-sections at 14.6 MeV incident neutron energy(Pergamon-Elsevier Science Ltd, 2023) Akkoyun, Serkan; Amrani, Naima; Bayram, TuncayIn this study, we have estimated the (n,2n) reaction cross-section for 14.6 MeV incident neutron energy by using the artificial neural network (ANN) method. We have also predicted the reaction cross-sections whose experi-mental data are not available in the literature. For the construction of the present ANN, available experimental data in the literature has been borrowed. The ANN estimations have been compared with the available exper-imental data and the results from a theoretical calculation and the two commonly used computer codes. Ac-cording to the results that the ANN results are in good agreement with the experimental data than the codes and this shows that the method can be a powerful tool for the estimation of cross-section data for the neutron-induced reactions. Considering the predictions of the ANN of the cross-sections whose experimental data are not available in the literature, it is seen that they are in line with the trend of the experimental data, but far from the results given by the theoretical calculations and two computer codes.Öğe NEW PARAMETERS FOR NUCLEAR CHARGE RADIUS FORMULAS(WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO, 2013) Bayram, Tuncay; Akkoyun, Serkan; Kara, S. Okan; Sinan, AlperParameters of widely used nuclear rms charge radius formulas have been refitted based on the latest experimental data for about 900 nuclei. It has been seen that the new parameters in the formulas give better results than the previous ones. Besides, an N-1/3-dependent formula has been proposed and discussed. This formula gives effective results for rms charge radius. The standard deviation in all formulas with new parameters are concentrated between -0.1 and 0.1. In other words, for about 90% of nuclei, the differences of charge radii from experimental values are lower than 0.1 fm.Öğe Nuclear Shell Model Calculations for Ca Isotopes(2020) Akkoyun, Serkan; Ayhan, Yasemin; Bayram, TuncayEnergies of nuclear excited states of nuclei, nuclear spin/parity and transition probabilities between nuclear levelscan be calculated in the scope of nuclear shell model. The nuclei having magic numbers are used as inert core inthe calculations. It is assumed that the nucleons in the inert core do not move outside from the core. Only valancenucleons out of the core are considered in the shell model calculations. In this study, the nuclear energy levels ofeven-even 42-56Ca isotopes have been calculated by the nuclear shell model using KShell computer code. This codeenables us to perform nuclear shell-model calculations with M-scheme representation. In the calculations, doublymagic 40Ca isotope was taken as core. For the neutrons, 0f7/2, 1p3/2, 0f5/2 and 1p1/2 orbits are considered as modelspace. Excited nuclear level spins, parities and energies have been obtained for Ca isotopes. The results have beencompared with the available experimental values in the literature.Öğe Nükleer Kabuk Modeli ile Ne İzotoplarının Nükleer Yapısının İncelenmesi(2021) Akkoyun, Serkan; Bayram, TuncayAtom çekirdeklerinin nükleer yapılarını araştırma amacıyla kullanılan yaygın yöntemlerden birisi de nükleer kabuk modelidir. Atom elektronlarının yörüngelere yerleşmesine benzer şekilde, nükleer kabuk modelinde de proton ve nötronların, Pauli dışarlama ilkesine uyarak çekirdek içerisinde yörüngelere yerleştiği düşünülmektedir. Bu yörüngeler, kendi aralarında gruplanarak kabukları meydana getirmektedir ki, bir kabuktaki tüm mümkün seviyelerin dolu olması durumunda, kabuğun kapalı olduğu söylenir. Kapalı kabuğa sahip atom çekirdekleri oldukça kararlıdırlar ve nükleer kabuk modeli hesaplamalarında bu çekirdeklerden fazla olan değerlik nükleonları hesaplamalara katılır. Bu çalışmada, 16O çekirdeği kapalı kabuk çekirdeği olarak ele alınarak, çift-çift Ne çekirdeklerinin nükleer yapılarını araştırmak için nükleer kabuk modeli kullanılmıştır. Tek parçacık yörüngeleri olarak d5/2, s1/2 ve d3/2 ele alınarak, değerlik nükleonları arasındaki iki cisim etkileşmeleri için farklı parametre setleri kullanılmıştır. Sonuçlar birbirleriyle ve mevcut literatür değerleriyle karşılaştırılmıştır. Deneysel değerlere en yakın sonuçların, usdb ve sdnn parametre setleri ile elde edildiği görülmüştür. Sihirli nötron sayılı 18Ne izotopunda, ilk uyarılmış seviye enerjisinin beklendiği gibi fazla olduğu görülmüştür. Ardından 20Ne ve 22Ne çekirdekleri için bu uyarılma enerjisi düşmekte ve sonra yörüngelerin tam dolu hale gelmesi ile tekrar yükselmektedir.Öğe Probing for leptophilic gauge boson Z(l) at ILC with root s=1 TeV by using ANN(WORLD SCIENTIFIC PUBL CO PTE LTD, 2014) Kara, S. Okan; Akkoyun, Serkan; Bayram, TuncayWe search for leptophilic gauge boson Z(l) via the process e(+)e(-) -> mu(+)mu(-) ILC with root s = 1 TeV. In the leptonic extension of SM (SUC(3) x SUW(2) x U-Y (1) x U-l' (1)) we have predicted that ILC with root s = 1 TeV will enable searching Z(l) with masses up to the center-of-mass energy if the related coupling constant g(l) exceeds 10(-3) for 3 sigma observations and 5 sigma discovery. Furthermore similar results have been obtained by using artificial neural network (ANN) method.Öğe Production cross-section and reaction yield of 82Sr for 82Sr/82Rb generator(2022) Şentürk, Şevki; Bayram, Tuncay; Akkoyun, SerkanThere are many radioisotopes used for diagnostic and therapeutic purposes in nuclear medicine. One of the radioisotopes used for diagnostic purposes is 82Rb. It is used in positron emission tomography (PET) as to be positron emitter and commonly obtained from 82Sr/82Rb generator. In this study, we have investigated some possible production mechanisms of 82Sr by regarding 82Sr/82Rb generator. 85,87Rb(p,xn)82Sr and 80,82,83,84,86Kr(3He,xn)82Sr reaction channels have been investigated using the CTFGM, BSFGM, and GSM models within the framework of TALYS nuclear reaction code. It has been seen that the production cross-sections, reaction yields and total activation values calculated up to 60 MeV beam energy value are in agreement with the available data in the literature.Öğe Shell Model Calculations for Proton-rich Zn Isotopes via New Generated Effective Interaction by Artificial Neural Networks(Sivas Cumhuriyet University, 2019) Akkoyun, Serkan; Bayram, TuncayIn this study, the artificial neural network method has been employed for the generation of the new two-body matrix elements which is used for fpg shell nuclei. For this purpose, jj44b interaction Hamiltonian has been considered as a source. After the generation of the new Hamiltonian, both, original and new generated, are tested on proton-rich Zn isotopes. According to the results, the calculated values are close to the each other. As well the results from new interaction (jj44b_nn) are closer to the available experimental values in some cases.Öğe A study on ground-state energies of nuclei by using neural networks(PERGAMON-ELSEVIER SCIENCE LTD, 2014) Bayram, Tuncay; Akkoyun, Serkan; Kara, S. OkanOne of the fundamental ground-state properties of nuclei is binding energy. Artificial neural networks (ANN) have been performed to obtain binding energies of nuclei based on the data calculated from Hartree-Fock-Bogolibov method with two Skyrme forces SLy4 and SKP. ANN has been employed to obtain two-neutron and two-proton separation energies of nuclei. Statistical modeling of ground-state energies using ANN has been seen as to be successful in this study. Particularly, predictive power of ANN has been drawn from estimations for energies of Sr, Xe, Er and Pb isotopic chains which are not seen before by the network. The study shows that such a statistical model can be possible tool for searching in systematic of nuclei beyond existing experimental data. (C) 2013 Elsevier Ltd. All rights reserved.Öğe A study on structural evolution of Nd142-164 isotopes(IOP PUBLISHING LTD, 2014) Kara, Seyit O.; Bayram, Tuncay; Akkoyun, Serkan; Vagenas, EC; Vlachos, DSConstrained Hartree-Fock-Bogoliubov theory with SLy5 Skyrme force has been applied for even-even Nd142-164 isotopes to investigate the structural evolution of Nd isotopic chain. In this work, ground-state energies and charge radii of Nd isotopes have been carried out as in good agreement with the experimental data. The systematic investigation of ground-state shape evolution between spherical U(5) and axially deformed SU(3) for Nd142-164 has been studied by using potential energy curves.
