Effects of the tensor force on the ground and first 2+2^{+} states of the magic 54^{54}Ca nucleus

The magic nature of the $^{54}$Ca nucleus is investigated in the light of the recent experimental results. We employ both HFB and HF+BCS methods using Skyrme-type SLy5, SLy5+T and T44 interactions. The evolution of the single-particle spectra is studied for the N=34 isotones: $^{60}$Fe, $^{58}$Cr, $^{56}$Ti and $^{54}$Ca. An increase is obtained in the neutron spin-orbit splittings of $p$ and $f$ states due to the effect of the tensor force which also makes $^{54}$Ca a magic nucleus candidate. QRPA calculations on top of HF+BCS are performed to investigate the first $J^{\pi}$=$2^{+}$ states of the calcium isotopic chain. A good agreement for excitation energies is obtained when we include the tensor force in the mean-field part of the calculations. The first $2^{+}$ states indicate a subshell closure for both $^{52}$Ca and $^{54}$Ca nuclei. We confirm that the tensor part of the interaction is quite essential in explaining the neutron subshell closure in $^{52}$Ca and $^{54}$Ca nuclei.Comment: 8 pages, 3 figure

Spectral splits of neutrinos as a BCS-BEC crossover type phenomenon

We show that the spectral split of a neutrino ensemble which initially consists of electron type neutrinos, is analogous to the BCS-BEC crossover already observed in ultra cold atomic gas experiments. Such a neutrino ensemble mimics the deleptonization burst of a core collapse supernova. Although these two phenomena belong to very different domains of physics, the propagation of neutrinos from highly interacting inner regions of the supernova to the vacuum is reminiscent of the evolution of Cooper pairs between weak and strong interaction regimes during the crossover. The Hamiltonians and the corresponding many-body states undergo very similar transformations if one replaces the pair quasispin of the latter with the neutrino isospin of the former.Comment: 9 pages, 5 figure

OLPT CONDUCTIVITY IN WOLLASTONITE INLAID NR/SBR TYPE ELASTOMER BASED MATERIAL

The electrical properties of wollastonite inlaid NR/SBR type elastomer based material have been evaluated. Electrical properties of the samples were measured in the temperature range of 303 to 453 K and the frequency range of 100 Hz – 40 MHz. All electrically measured parameters were given anomalies at 385 K. Only one type of dielectric relaxation process have been observed for all measurements. Physical parameters characterizing the dielectric behavior have been obtained by fitting the experimental results in the modified Debye equation. The activation energy which is thermally activated by dielectric relaxation process have been calculated to be 0.58 eV. DC conductivity increasing by temperature has been explained with the help of VFT model whereas the AC one has been clarified by the OLPT model

Dynamic phase transition properties and hysteretic behavior of a ferrimagnetic core-shell nanoparticle in the presence of a time dependent magnetic field

We have presented dynamic phase transition features and stationary-state behavior of a ferrimagnetic small nanoparticle system with a core-shell structure. By means of detailed Monte Carlo simulations, a complete picture of the phase diagrams and magnetization profiles have been presented and the conditions for the occurrence of a compensation point $T_{comp}$ in the system have been investigated. According to N\'{e}el nomenclature, the magnetization curves of the particle have been found to obey P-type, N-type and Q-type classification schemes under certain conditions. Much effort has been devoted to investigation of hysteretic response of the particle and we observed the existence of triple hysteresis loop behavior which originates from the existence of a weak ferromagnetic core coupling $J_{c}/J_{sh}$, as well as a strong antiferromagnetic interface exchange interaction $J_{int}/J_{sh}$. Most of the calculations have been performed for a particle in the presence of oscillating fields of very high frequencies and high amplitudes in comparison with exchange interactions which resembles a magnetic system under the influence of ultrafast switching fields. Particular attention has also been paid on the influence of the particle size on the thermal and magnetic properties, as well as magnetic features such as coercivity, remanence and compensation temperature of the particle. We have found that in the presence of ultrafast switching fields, the particle may exhibit a dynamic phase transition from paramagnetic to a dynamically ordered phase with increasing ferromagnetic shell thickness.Comment: 12 pages, 12 figure

Swift observation of Segue 1: constraints on sterile neutrino parameters in the darkest galaxy

Some extensions of standard particle physics postulate that dark matter may be partially composed of weakly interacting sterile neutrino particles that have so far eluded detection. We use a short (~5 ks) archival X-ray observation of Segue 1 obtained with the X-ray Telescope (XRT) onboard the Swift satellite to exclude the presence of sterile neutrinos in the 1.6 - 14 keV mass range down to a flux limit of 6 x 10^{-12} erg cm-2 s-1 within 67 pc of its centre. With an estimated mass-to-light ratio of ~3400 Msun/Lsun, Segue 1 is the darkest ultrafaint dwarf galaxy currently measured. Spectral analysis of the Swift XRT data fails to find any non-instrumental spectral feature possibly connected with the radiative decay of a dark matter particle. Accordingly, we establish upper bounds on the sterile neutrino parameter space based on the non-detection of emission lines in the spectrum. The present work provides the most sensitive X-ray search for sterile neutrinos in a region with the highest dark matter density yet measured.Comment: 5 pages, 3 figures. Accepted in MNRAS Letter

Güneş Enerjili Kurutma Sistemlerinde Parafin Kullanılarak Boya Çamurunun Kurutulması

Güneş kurutucu sistemi, ileri bir doğal güneş kurutma teknolojisi olarak geniş alanlardada kullanılmaktadır. Bu çalışmanın amacı; atık boya çamurunun yönetimi sürecinde güneşle kurutmayı alternatif bir proses olarak incelemektir. Çalışmada faz değiştirme malzemesi olarak parafin içeren bir güneş kurutma sistemi tasarlanarak kurutma verimliliği araştırılmıştır. Kurutulan çamur kalınlığının düşük olması sebebiyle kurutma sırasında karıştırmanın etkisi gözlenememiştir. Kurutma işlemi 8 saatte 1849 Wh/m2 kümülatif güneş radyasyonu ile yapılmıştır. İç sıcaklık, nem, güneş radyasyonu, zaman, çamur kütlesi ve hacmini azaltmanın yanı sıra kurutucuda kullanılan ekipmanlar ısı transferini güçlendirmek için önemli faktörler olarak belirlenmiştir. Sistemde fan ile oluşturulan hava sirkülasyonunun yetersiz olduğu hesaplamalı akışkanlar dinamiği (HAD) ile tespit edilmiştir, ve simülasyon modeli kurutma sisteminin optimize edilmesi için kullanılmıştır. Gözenekli yapının oluşumu, bir tarama elektron mikroskobu (SEM) kullanılarak kurutulmuş çamurda gözlenmiştir. Atık boya çamurunun yönetiminde güneş kurutucusunun geliştirilmeler sonrası kullanılabilecek bir alternatif olduğu sonucuna varılmıştır

Kritik (Kriz) Dönem Enflasyon Hesaplamalarında Bulanık Regresyon Tahminlemesi

Inflation targeting is defined as the determination of an acceptable inflation rate for a specific period of time by considering the general variables and data of inflation and also as the implementation of monetary policies in such a way that they can reach predetermined rates. Accurate inflation estimates are needed to reach the targets. Acquiring the estimations accurately leads to correct decisions. Fuzzy regression method is a method that gives successful results when classical regression estimates cannot be obtained. During the periods when Turkey undergoes economical crisis, it is difficult to make accurate inflation estimates. More reliable estimates can be made with the help of fuzzy regression models. In this study, inflation estimates were obtained through fuzzy regression model estimation and the results were interpreted.Enflasyon hedeflemesi, ekonominin genel değişkenlerinin ve verilerinin dikkate alınarak belirli bir dönem için kabul edilebilir bir enflasyon oranının belirlenmesi ve para politikalarının belirlenen orana ulaşacak şekilde yürütülmesi olarak tanımlanmaktadır. Hedeflere ulaşabilmek için güçlü enflasyon tahminlerine gereksinim duyulmaktadır. Öngörülerin doğru bir şekilde elde edilmesi daha doğru kararlara neden olmaktadır. Bulanık regresyon yöntemi, klasik regresyon varsayımlarının sağlanmadığı durumlarda başarılı sonuçlar veren bir yöntemdir. Türkiye’nin ekonomik kriz yaşadığı dönemlerde güçlü enflasyon tahminleri yapmak oldukça zor olmaktadır. Bulanık regresyon modelleri yardımıyla daha güvenilir tahminler elde edilebilmektedir. Bu çalışmada, bulanık regresyon model tahminlemesi ile kritik dönemler için enflasyon tahminleri elde edilmiş ve sonuçlar yorumlanmıştır

Kritik (Kriz) Dönem Enflasyon Hesaplamalarında Bulanık Regresyon Tahminlemesi

Inflation targeting is defined as the determination of an acceptable inflation rate for a specific period of time by considering the general variables and data of inflation and also as the implementation of monetary policies in such a way that they can reach predetermined rates. Accurate inflation estimates are needed to reach the targets. Acquiring the estimations accurately leads to correct decisions. Fuzzy regression method is a method that gives successful results when classical regression estimates cannot be obtained. During the periods when Turkey undergoes economical crisis, it is difficult to make accurate inflation estimates. More reliable estimates can be made with the help of fuzzy regression models. In this study, inflation estimates were obtained through fuzzy regression model estimation and the results were interpreted.Enflasyon hedeflemesi, ekonominin genel değişkenlerinin ve verilerinin dikkate alınarak belirli bir dönem için kabul edilebilir bir enflasyon oranının belirlenmesi ve para politikalarının belirlenen orana ulaşacak şekilde yürütülmesi olarak tanımlanmaktadır. Hedeflere ulaşabilmek için güçlü enflasyon tahminlerine gereksinim duyulmaktadır. Öngörülerin doğru bir şekilde elde edilmesi daha doğru kararlara neden olmaktadır. Bulanık regresyon yöntemi, klasik regresyon varsayımlarının sağlanmadığı durumlarda başarılı sonuçlar veren bir yöntemdir. Türkiye’nin ekonomik kriz yaşadığı dönemlerde güçlü enflasyon tahminleri yapmak oldukça zor olmaktadır. Bulanık regresyon modelleri yardımıyla daha güvenilir tahminler elde edilebilmektedir. Bu çalışmada, bulanık regresyon model tahminlemesi ile kritik dönemler için enflasyon tahminleri elde edilmiş ve sonuçlar yorumlanmıştır

Influence of coumarin as an additive on CuO nanostructures prepared by successive ionic layer adsorption and reaction (SILAR) method

The effect of coumarin doping during the growth of CuO nanostructures by SILAR method has been studied. It was found that coumarin considerably influences the growth process, manipulates the bandgap and modifies the crystallite size of the films. XRD experiments evidenced that with higher coumarin concentrations in the growth solution, the microstrain and dislocation density increased, while the crystallite size of the films decreased. SEM images revealed that the thicknesses of the plate-like nanostructures decreased with increasing coumarin concentration. By UV/vis spectrophotometer analysis it is found that the coumarin concentration affects both the optical band gap and the transmission rate: both the band gap and spectral transmittance values of the films decreased for higher coumarin content. © 2013 Elsevier B.V. All rights reserved

Neutrino Spectrum from SN 1987A and from Cosmic Supernovae

The detection of neutrinos from SN 1987A by the Kamiokande-II and Irvine-Michigan-Brookhaven detectors provided the first glimpse of core collapse in a supernova, complementing the optical observations and confirming our basic understanding of the mechanism behind the explosion. One long-standing puzzle is that, when fitted with thermal spectra, the two independent detections do not seem to agree with either each other or typical theoretical expectations. We assess the compatibility of the two data sets in a model-independent way and show that they can be reconciled if one avoids any bias on the neutrino spectrum stemming from theoretical conjecture. We reconstruct the neutrino spectrum from SN 1987A directly from the data through non-parametric inferential statistical methods and present predictions for the Diffuse Supernova Neutrino Background based on SN 1987A data. We show that this prediction cannot be too small (especially in the 10-18 MeV range), since the majority of the detected events from SN 1987 were above 18 MeV (including 6 events above 35 MeV), suggesting an imminent detection in operational and planned detectors.Comment: 9 pages, 4 figures; Matches version published in Phys. Rev.