168-178Yb izotop zinciri çekirdeğinin dev dipol rezonanslarının araştırılması

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Bu tez çalışmasında 168-178Yb izotop zinciri çekirdeklerinin spini ve paritesi olan elektrik dipol uyarılmalarının yüksek enerji bölgesinde bulunan dev dipol rezonans (GDR) özellikleri araştırılmıştır. Çift-çift deforme özellikte olan bu izotopların sistematik GDR özellikleri Kuazi Parçacık Rastgele Faz (QRPA) yaklaşımı çerçevesinde incelenmiştir. Bu yaklaşımla ortalama potansiyelin kırılan simetrisinin restorasyonunda ayrılabilir izoskaler ve izovektör etkileşmeler özuyumlu olarak belirlenmiştir. İzovektör dipol-dipol etkileşmeleri içeren modelde, deforme çekirdeklerde K=0 ve K=1 dallarında GDR'nin yarılmasını, enerjilerini, deneysel verilere uygun bir şekilde açıklamaktadır. Öteleme ve Galileo değişmezliğin restore edildiği Model (TGI QRPA) ile restorasyonun gerçekleşmediği (NTGI QRPA), yalnız öteleme değişmezliğin (TI QRPA) ve yalnız Galileo değişmezliğin (GI QRPA) restore edilmesiyle elde edilen modeller karşılaştırılmıştır. Buradan, gerçekleştirilen restorasyonların spektruma karışan sıfır enerjili sahte hallerin (Goldstone modu) ayrılmasına katkısı incelenmiştir. Hamiltonyen'e eklenen restorasyon kuvvetlerinin B(E1) spektrumunda dağılımı değiştirdiği ve B(E1) gücünü azaltarak seviye sayılarını arttırdığı görülmüştür. Çift-çift 168-178Yb izotoplarının ve geçişleri için ayrı ayrı indirgenmiş geçiş olasılıkları B(E1), enerji ağırlıklı indirgenmiş geçiş olasılıkları ωB(E1), enerji ( ), fotoabsorbsiyon tesir kesiti ( ), asimptotik kuantum numaraları , radyasyon kalınlıkları (E1), indirgenmiş radyasyon kalınlıkları red(E1) ve integre edilmiş tesir kesitleri , , değerleri TGI QRPA model çerçevesinde hesaplanmıştır. Hesaplamalar sonucunda GDR bölgesinde K=1 dalının baskın olduğu görülmüştür. Deneysel verilerle karşılaştırma yapılabilen en karakteristik büyüklük olan toplam fotoabsorbsiyon tesir kesitinin deforme 168-178Yb izotopları için K=0 dalında 11-12 MeV K=1 dalında 15-16 MeV aralıklarında enerji maksimumlarına sahip olduğu görülmüştür. İncelenen izotoplar için iki hörgüçlü yapıya sahip spektrumlar deneysel veriler ile uyumlu sonuçlar vermiştir.Giant dipole resonance (GDR) feature of the electric dipole excitations with spin and parity in the high energy region has been searched for the 168-178Yb isotopes in this thesis. The systematic of GDR structure of even-even deformed 168-178Yb isotopes has been investigated in the framework of the Quasi-Random Phase Approximation (QRPA). Separable isoscaler and isovector interactions in the restoration of broken symmetries in the mean-field potential have been determined self consistently. The model consisting of isovector dipole-dipole interactions successfully explains the K = 0 and K = 1 branch of GDR and energy in an agreement with experimental data. The models in which translational and Galilean invariance non-restored (NTGI QRPA), only translational invariance restored (TI QRPA) and only Galilean invariance (GI QRPA) restored have been compared and the contribution of these models to discrimination of zero energy spurious states (Goldstone mode) from the spectrum. The restoration forces added to the Hamiltonian has changed the distribution of B(E1) spectrum, weaken the B(E1) and increased the number of levels. The reduced transition probabilities B(E1), energy weighted reduced transition probabilities ωB(E1), energy ( ), photoabsoprtion cross section ( ) and Nilsson asymptotic quantum numbers , radiation witdh (E1), reduced radiation witdh red(E1) and integrated cross sections , , have been calculates for even-even 168-178Yb isotopes using TGI QRPA model. The calculations revealed that the K=1 branch of the GDR region dominates the energy spectrum. One the convenient parameter which is comparable with experimental data is photoabsoprtion cross section ( ) is found that having a peak around 11-12 MeV in the K = 0 branch and 15-16 MeV in the K = 1 branch. These double humps structure are in good agreement with experimental data

Analysis of Queueing System MMPP/M/K/K with Delayed Feedback

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Analysis of Instantaneous Feedback Queue with Heterogeneous Servers

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Retrial Queuing-Inventory Systems with Delayed Feedback and Instantaneous Damaging of Items

This paper studies a Markov model of a queuing-inventory system with primary, retrial, and feedback customers. Primary customers form a Poisson flow, and if an inventory level is positive upon their arrival, they instantly receive the items. If the inventory level is equal to zero upon arrival of a primary customer, then this customer, according to the Bernoulli scheme, either leaves the system or goes into an infinite buffer to repeat their request in the future. The rate of retrial customers is constant, and if the inventory level is zero upon arrival of a retrial customer, then this customer, according to the Bernoulli scheme, either leaves orbit or remains in orbit to repeat its request in the future. According to the Bernoulli scheme, each served primary or retrial customer either leaves the system or feedbacks into orbit to repeat their request. Destructive customers that form a Poisson flow cause damage to items. Unlike primary, retrial, and feedback customers, destructive customers do not require items, since, upon arrival of such customers, the inventory level instantly decreases by one. The system adopted one of two replenishment policies: (s, Q) or (s, S). In both policies, the lead time is a random variable that has an exponential distribution. It is shown that the mathematical model of the system under study was a two-dimensional Markov chain with an infinite state space. Algorithms for calculating the elements of the generating matrices of the constructed chains were developed, and the ergodicity conditions for both policies were found. To calculate the steady-state probabilities, a matrix-geometric method was used. Formulas were found for calculating the main performance measures of the system. The results of the numerical experiments, including the minimization of the total cost, are demonstrated

Retrial Queuing-Inventory Systems with Delayed Feedback and Instantaneous Damaging of Items

This paper studies a Markov model of a queuing-inventory system with primary, retrial, and feedback customers. Primary customers form a Poisson flow, and if an inventory level is positive upon their arrival, they instantly receive the items. If the inventory level is equal to zero upon arrival of a primary customer, then this customer, according to the Bernoulli scheme, either leaves the system or goes into an infinite buffer to repeat their request in the future. The rate of retrial customers is constant, and if the inventory level is zero upon arrival of a retrial customer, then this customer, according to the Bernoulli scheme, either leaves orbit or remains in orbit to repeat its request in the future. According to the Bernoulli scheme, each served primary or retrial customer either leaves the system or feedbacks into orbit to repeat their request. Destructive customers that form a Poisson flow cause damage to items. Unlike primary, retrial, and feedback customers, destructive customers do not require items, since, upon arrival of such customers, the inventory level instantly decreases by one. The system adopted one of two replenishment policies: (s, Q) or (s, S). In both policies, the lead time is a random variable that has an exponential distribution. It is shown that the mathematical model of the system under study was a two-dimensional Markov chain with an infinite state space. Algorithms for calculating the elements of the generating matrices of the constructed chains were developed, and the ergodicity conditions for both policies were found. To calculate the steady-state probabilities, a matrix-geometric method was used. Formulas were found for calculating the main performance measures of the system. The results of the numerical experiments, including the minimization of the total cost, are demonstrated