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Öğe 106Sg, 107Bh and 108Hs çekirdekleri için Alfa Bozunum Enerjilerinin Belirlenmesi(2016) Akkoyun, Serkan; Bayram, TuncayHem teorik hem de deneysel bakış açısıyla, super ağır bölgenin özelliklerini anlamak için, buradaki çekirdeklerin alfa bozunum özelliklerini incelemek oldukça ilgi çekicidir. Nükleer fizikteki pek çok olguda başarılı sonuçlar veren yapay sinir ağları (YSA), super ağır çekirdeklerin deneysel alfa bozunum enerjileri üzerinde kullanılmış ve Sg, Bh ve Hs çekirdeklerinin alfa bozunum enerjileri bu yöntemle tahmin edilmiştir. Farklı modeldeki YSA'lar veriler üzerinde test edilmiştir. Bu çalışmanın sonuçları, YSA metodunun bu iş için uygun olduğunu göstermektedir. Sonuçlara ait ortalama kare hatalar, ½1-1,5 civarındadır. En iyi sonuçlar, bulanık mantık YSA modeli ile elde edilmiştirÖğe 116,117,118,119,120,124Sn ve233,234,235,236,238U İzotopları İçin Dev Dipol RezonansEnerjilerinin Kestirimi(2017) Akkoyun, Serkan; Bayram, Tuncay; Özgüven, YücelDev dipol rezonans (GDR) parametrelerini elde etmek için birçok deneysel ve teorik metot uygulanmaktadır.Bu çalışmada, Sn ve U izotopları için GDR enerjileri, yapay sinir ağları (YSA) metodu ile tahmin edilmiştir. Sonuçlara göre, YSA'nın eğitiminde deneysel verilerden ortalama sapma, %1 seviyesindedir. Sn ve U izotopları için tahmin edilen enerjilerdeki ortalama kare hata, 0,034 MeV'dir.Teorik bir model için ise hata, 0,061 MeV'dir.Bu sonuç, GDR enerjileri üzerinde ANN tahmininin, teorik hesaplamalardaki sonuçlardan daha iyi olduğunu göstermektedir.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 142-164Nd isotopes(Journal of Physics: Conference Series, 2014) Kara, Seyit Okan; Bayram, Tuncay; Akkoyun, SerkanConstrained Hartree-Fock-Bogoliubov theory with SLy5 Skyrme force has been applied for even-even 142-164Nd 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 142-164Nd has been studied by using potential energy curves.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, SerkanThe 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 ?-decay half-life calculations of superheavy nuclei using artificial neural networks(Journal of Physics: Conference Series, 2014) Bayram, Tuncay; Akkoyun, Serkan; Kara, Seyit OkanInvestigations of superheavy elements (SHE) have received much attention in the last two decades, due to the successful syntheses of SHE. In particular, ?-decay of SHEs has a great importance because most synthesized SHE have a-decay and the experimentalists have evaluated the theoretical predictions of the a-decay half-life during the experimental design. Because of this, the correct prediction of ?-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 a-decay half-lives of superheavy nuclei. Statistical modeling of a-decay half-life of superheavy nuclei have been found as to be successful.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 HALF-LIVES OF 47Sc ISOTOPE FROM PHOTONUCLEAR REACTIONS(Rad Assoc, 2016) Akkoyun, Serkan; Kocak, Gokhan; Bayram, TuncayIn 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 Improvement studies on neutron-gamma separation in HPGe detectors by using neural networks(Cumhuriyet Science Journal, 2013) Akkoyun, Serkan; Bayram, Tuncay; Kara, Seyit OkanThe neutrons emitted in heavy-ion fusion-evaporation (HIFE) reactions together with the gamma-rays cause unwanted backgrounds in gamma-ray spectra. Especially in the nuclear reactions where relativistic ion beams (RIBs) are used, these neutrons are serious problem. They have to be rejected in order to obtain clearer gamma-ray peaks. In this study, the radiation energy and three criteria which are previously determined for separation of neutron and gamma-rays in the HPGe detectors have been used in artificial neural network (ANN) for improving of the decomposition power. According to the preliminary results, by the help of ANN method, the ratio of neutron rejection has been improved by a factor of 1.27 and the ratio of the lost in gamma-rays has been decreased by a factor of 0.5.Öğe New Parameters for Nuclear Charge Radius Formulas(Acta Physica Polonica B, 2013) Bayram, Tuncay; Akkoyun, Serkan; Kara, Seyit 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 N1?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 Probing for leptophilic gauge boson Zl at ILC with √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 Relativistik Ortalama Alan Modeli İçin Nükleer Etkileşme Parametrelerinin İyileştirilmesi(2017) Bayram, Tuncay; Akkoyun, SerkanKararlı bölgedeki çekirdekler ile proton ve nötron bakımından zengin olan çekirdekleri de kapsayan geniş bir bölgede bağlanma enerjisi, tek parçacık enerji seviyeleri, elektrik momentler, yük ve nükleon yarıçapları gibi çekirdek özelliklerinin hesaplanabilmesi, ortalama alan yaklaşımı kullanılarak yapılabilmektedir. Kuantum hidrodinamiği temelli Relativistik Ortalama Alan (RMF) modeli, gerek fenomenolojisinden kaynaklı nükleer etkileşmeyi betimlemedeki başarısı ve gerekse daha yoğun nükleer madde araştırmalarında kullanılabilme özelliğinden dolayı başarılı bir modeldir. Bu model, nükleonların çeşitli mezonların değiş-tokuşu ile etkileştiği varsayımı üzerine kuruludur. Bundan dolayı mezon kütleleri, mezon-nükleon çiftlenim (kuplaj) sabitleri ve bazı mezonlar için öz çiftlenim terimleri az sayıda çekirdeğin deneysel verileri yardımı ile ayarlanarak periyodik tabloyu kapsayan geniş bir bölgede çekirdeklerin nükleer taban durum nükleer özellikleri hesaplanabilmektedir. Bu da, mezon kütleleri ve etkileşme sabitlerinden oluşan parametre setinin iyi belirlenmesini gerektirmektedir. Bu proje kapsamında doğrusal (lineer) olmayan RMF modeli için parametre setinin, standart fitleme yerine, doğrusal olmayan ilişkilerin belirlenmesinde başarılı bir biçimde kullanılan Yapay Sinir Ağları (YSA) ile nasıl iyileştirilebileceği üzerine bir araştırma yapılmıştır. Bu çerçevede DEFNE olarak adlandırılan yeni bir RMF model parametre seti geliştirilerek periyodik tabloyu kapsayan geniş bir bölgede bu yeni parametre setinin etkinliği test edilmiştir. Bu proje sayesinde YSA metodunun RMF modeli parametre setlerinin değerleri ile bu parametrelerin RMF modelinde kullanılması ile elde edilen çeşitli nükleer özelliklerin değerleri arasındaki doğrusal olmayan ilişkiyi belirleyebildiği ortaya çıkarılmıştır. Bu belirlemenin ardından RMF modeli için DEFNE olarak adlandırılan parametre seti geliştirilmiştir. Bu parametre seti periyodik tabloda hafiften ağır çekirdek bölgesine doğru uzanan yaklaşık 140 çekirdeğin taban durum bağlanma enerjisi ve yük yarıçapının RMF modeli ile hesaplanmasında kullanılmıştır. Elde edilen çekirdek taban durum bağlanma enerjisi değerleri RMF modeli için geliştirilmiş NL3* parametre setinden elde edilen değerler, Hartree-FockBogoliubov metodu (SKP ve SLy4 parametre setleri ile) sonuçları ve sıvı damlası modelinden elde edilen değerler ile karşılaştırılmıştır. Yapılan analizler sonucunda yeni geliştirilen DEFNE parametre setinin periyodik tabloyu kapsayan geniş bir bölgede çekirdek bağlanma enerjileri ve yük yarıçaplarının başarılı bir şekilde tahmininde etkin olduğu belirlenmiştir. Ayrıca geliştirilen bu yeni parametre seti ile 2197 çift-çift çekirdek için hesaplanmış taban durum bağlanma enerjilerini, iki-proton ve iki-nötron ayırma enerjilerini, nötron, proton ve yük yarıçaplarını, nöron, proton ve toplam kuadrupol momentlerini, hegzadekupol momentlerini, kuadrupol moment deformasyon parametrelerini ve hegzadekupol moment deformasyon parametrelerini kapsayan nükleer veri tablosu oluşturulmuştur. Bununla birlikte geliştirilen bu parametre setinin nükleer madde özellikleri incelendiğinde çekirdeklerin yüzey özelliklerinin belirlenmesinde çok etkin olmayabileceği sonucuna varılabilir. Bu durum sigma mezonun öz etkileşme terimlerinden kaynaklı olup RMF modeli için parametre setinin geliştirilmesi süreçlerinde mezon-nükleon ve mezonların öz etkileşme parametrelerinin birbirinden bağımsız olarak ele alınması önerilmektedir.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, SevkiI-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 Transition energy and half-life determinations of photonuclear reaction products of erbium nuclei(World Scientific Publ Co Pte Ltd, 2016) Bayram, Tuncay; Akkoyun, Serkan; Uruk, Serhat; Dapo, Haris; Dulger, Fatih; Boztosun, IsmailPhoton induced reactions are called as photonuclear reactions and used in many research fields of nuclear science and nuclear physics. The photonuclear data are used in many nuclear applications such as radiation shielding and protection, radiation transport analyses, reactor core design, activation analysis and nuclear waste transmutation. In the past, many studies had been devoted to extract photonuclear data covering the isotopic chart. However, there is still lack of existing data. In the present study, we have performed photonuclear reactions on erbium (Er) target by using clinical electron linear accelerators (cLINAC). By using measured residual activity of photonuclear reaction products of Er nuclei, we have determined the half-life of Er-161 nucleus and transition energies of Ho-161 nucleus. Also, new measurements on gamma-ray energies of the products have been determined accurately. Furthermore, this study shows that repurposed cLINAC with limited budget can contribute to the global nuclear science knowledge.
