Browsing by Author "Maras I."
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Item Calculation of the log(ft) values for the allowed gamow-teller transitions in deformed nuclei using the basis of woods-saxon wave functions(2003) Salamov D.I.; Kücükbursa A.; Maras I.; Aygör H.A.; Babacan T.; Bircan H.The present study investigates the log(ft) values of the allowed β± decay between odd-A deformed nuclei in the atomic mass regions of 125 ≤ A ≤ 131 and 159 ≤ A ≤ 181. Single particle energies and wave functions have been calculated with a deformed Woods-Saxon potential. Calculations have been performed within the framework of a proton-neutron quasi-particle random phase approximation (QRPA), including the schematic residual spinisospin interaction between nucleons in the particle-hole and particle-particle channels. It has been seen that the results obtained by using the values for the fixed particle-hole and particle-particle interaction strengths, ΧGTph = 5.2/A0.7 MeV and ΧGTpp = 0.58/A0.7 MeV, have good agreement with the experimental observations.Item The effect of the pairing interaction on the energies of isobar analogue resonances in 112-124Sb and isospin admixture in 100-124Sn isotopes(2004) Babacan T.; Salamov D.; Kücükbursa A.; Babacan H.; Maras I.; Aygör H.A.; Ünal A.In the present study, the effect of the pairing interaction and the isovector correlation between nucleons on the properties of the isobar analogue resonances (IAR) in 112-124Sb isotopes and the isospin admixture in 100-124Sn isotopes is investigated within the framework of the proton-neutron quasi-particle random phase approximation (pnQRPA). The form of the interaction strength parameter is related to the shell-model potential by restoring the isotopic invariance of the nuclear part of the total Hamiltonian. In this respect, the isospin admixtures in the 100-124Sn isotopes are calculated, and the dependence of the differential cross section and the volume integral JF for the Sn(3He,t)Sb reactions at E( 3He) = 200 MeV occurring by the excitation of IAR on mass number A is examined. Our results show that the calculated value for the isospin mixing in the 100Sn isotope is in good agreement with Colo et al's estimates (4-5%), and the obtained values for the volume integral change within the error range of the value reported by Fujiwara et al (53 ± 5 MeV fm 3). Moreover, it is concluded that although the differential cross section of the isobar analogue resonance for the (3He,t) reactions is not sensitive to pairing correlations between nucleons, a considerable effect on the isospin admixtures in N ≈ Z isotopes can be seen with the presence of these correlations.Item The isospin admixture of the ground state and the properties of the isobar analog resonances in medium and heavy mass nuclei(2006) Salamov D.I.; Babacan T.; Kücükbursa A.; Ünlü S.; Maras I.Within the framework of quasiparticle random phase approximation (QRPA), Pyatov-Salamov method [23] for the self-consistent determination of the isovector effective interaction strength parameter, restoring a broken isotopic symmetry for the nuclear part of the Hamiltonian, is used. The isospin admixtures in the ground state of the parent nucleus, and the isospin structure of the isobar analog resonance (IAR) state were investigated with the inclusion of the pairing correlations between nucleons for the medium and heavy mass regions: 80 < A < 90, 102 < A < 124, and 204 < A < 214. It was determined that the influence of the pairing interaction between nucleons on the isospin admixtures in the ground state and the isospin structure of the IAR. state is more pronounced for the light isotopes (N ≈ Z) of the investigated nuclei. © Indian Academy of Sciences.Item Microscopic interacting boson model calculations for even-even 128-138Ce nuclei(2007) Turkan N.; Maras I.In this study, we determined the most appropriate Hamiltonian that is needed for the present calculations of energy levels and B(E2) values of 128-138Ce nuclei which have a mass around A =≅ 130 using the interacting boson model (IBM). Using the best-fitted values of parameters in the Hamiltonian of the IBM-2, we have calculated energy levels and B(E2) values for a number of transitions in 128,130,132,134,136,138Ce. The results were compared with the previous experimental and theoretical (PTSM model) data and it was observed that they are in good agreement. Also some predictions of this model have better accuracy than those of PTSM model. It has turned out that the interacting boson approximation (IBA) is fairly reliable for calculating spectra in the entire set of 128,130,132,134,136,138Ce isotopes and the quality of the fits presented in this paper is acceptable. © Indian Academy of Sciences.Item The isospin admixture of the ground state and the properties of the isobar analog resonances in deformed nuclei(American Institute of Physics Inc., 2008) Aygor H.A.; Cakmak N.; Maras I.; Selam C.Within quasiparticle random phase approximation (QRPA), Pyatov-Salamov method for the self-consistent determination of the isovector effective interaction strength parameter, restoring a broken isotopic symmetry for the nuclear part of the Hamiltonian, is used. The isospin admixtures in the ground state of the parent nucleus, and the isospin structure of the isobar analog resonance (IAR) state are investigated by including the pairing correlations between nucleons for 72-80Kr isotopes. Our results are compared with the spherical case and with other theoretical results. © 2008 American Institute of Physics.Item E(5) behaviour of the Ge isotopes(Association for Scientific Research, 2010) Turkan N.; Maras I.The sufficient aspects of model leading to the E(5) symmetry have been proved by presenting E(5) characteristic of the transitional nuclei 64-80Ge. The positive parity states of even-mass Ge nuclei within the framework of Interacting Boson Model have been calculated and compared with the Davidson potential predictions along with the experimental data. It can be said that the set of parameters used in an calculations is the best approximation that has been carried out so far. Hence, Interacting Boson Approximation (IBA) is fairly reliable for the calculation of spectra in such set of Ge isotopes. © Association for Scientific Research.Item Search on results of ibm for region between 120≤A≤150: 120-128Te and 122-134Xe nuclei(Association for Scientific Research, 2011) Turkan N.; Maras I.In this work, the energy levels and transition probabilities B(E2) of some even-even Te (Z=52, N=68-80 and N=84) and even-even Xe nuclei (Z=54, N=68-80 and N=84-88) have been investigated by using the interacting boson model (IBM-1 and IBM-2). The results were compared with some previous experimental and theoretical values. It was seen that an acceptable degree of agreement between the predictions of the model (IBM-1 and IBM-2) and the experiment is achieved. Copyright © Association for Scientific Research.Item Quadrupole moments of some doubly-even molibden nuclei and the onset of collectivity(2012) Turkan N.; Ibis I.; Maras I.A good description of the quadrupole moments is obtained by investigating 94,96,98,100,102,104,106,108Mo isotopes in terms of the interacting boson model. After the positiveparity states and electromagnetic-transition rates B(E2) of even-mass Mo nuclei were calculated it was seen that there is a good agreement between the obtained results and some previous experimental data. At the end of the quadrupole moment calculations it was proved that the results agree well with the previous experimental data. © 2012 Pleiades Publishing, Ltd.Item Spin-isospin transitions in chromium isotopes within the quasiparticle random phase approximation(Elsevier Ltd, 2015) Cakmak S.; Nabi J.-U.; Babacan T.; Maras I.Beta decay and electron capture on isotopes of chromium are advocated to play a key role in the stellar evolution process. In this paper we endeavor to study charge-changing transitions for 24 isotopes of chromium ( 42-65 Cr). These include neutron-rich and neutron-deficient isotopes of chromium. Three different models from the QRPA genre, namely the pn-QRPA, the Pyatov method (PM) and the Schematic model (SM), were selected to calculate and study the Gamow-Teller (GT) transitions in chromium isotopes. The SM was employed separately in the particle-particle (pp) and pp + particle-hole (ph) channels. To study the effect of deformation, the SM was first used assuming the nuclei to be spherical and later to be deformed. The PM was used both in pp and pp + ph channels but only for the case of spherical nuclei. The pn-QRPA calculation was done by considering both pp and ph forces and taking deformation of nucleus into consideration. A recent study proved this version of pn-QRPA to be the best for calculation of GT strength distributions amongst the QRPA models. The pn-QRPA model calculated GT distributions had low-lying centroids and small widths as compared to other QRPA models. Our calculation results were also compared with other theoretical models and measurements wherever available. Our results are in decent agreement with previous measurements and shell model calculations. © 2014 COSPAR. Published by Elsevier Ltd. All rights reserved.