Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 32Citation - Scopus: 34The Cms Barrel Calorimeter Response To Particle Beams From 2 To 350 Gev/C(Springer Verlag, 2009) CMS HCAL/ECAL Collaborations; Sönmez, NasufThe response of the CMS barrel calorimeter (electromagnetic plus hadronic) to hadrons, electrons and muons over a wide momentum range from 2 to 350 GeV/c has been measured. To our knowledge, this is the widest range of momenta in which any calorimeter system has been studied. These tests, carried out at the H2 beam-line at CERN, provide a wealth of information, especially at low energies. The analysis of the differences in calorimeter response to charged pions, kaons, protons and antiprotons and a detailed discussion of the underlying phenomena are presented. We also show techniques that apply corrections to the signals from the considerably different electromagnetic (EB) and hadronic (HB) barrel calorimeters in reconstructing the energies of hadrons. Above 5 GeV/c, these corrections improve the energy resolution of the combined system where the stochastic term equals 84.7 ± 1.6% and the constant term is 7.4 ± 0.8%. The corrected mean response remains constant within 1.3% rms. © Springer-Verlag / Società Italiana di Fisica 2009.Conference Object Citation - WoS: 3Citation - Scopus: 3Photometric Multi-Site Campaign on Massive B Stars in the Open Cluster Chi Persei (ngc 884)(IOP Publishing, 2008) Saesen, S.; Pigulski, A.; Carrier, F.; De Ridder, J.; Aerts, C.; Handler, G.; Drummond, R.; Kalomeni, BelindaIn 2005 a photometric observation campaign started on the open cluster chi Persei, involving 13 telescopes spread over the whole northern hemisphere. After two years we gathered almost 1200 hours of data. We present here preliminary results on the variability search, especially from the 60-cm telescope in Bialkow (Poland), which show seven confirmed beta Cephei stars, four candidate B-type pulsators and other interesting variable stars.Conference Object Citation - WoS: 7Citation - Scopus: 7Carbon Deposition on the Stainless Steels Substrates Using Pulsed Plasma(National Institute of Optoelectronics, 2008) Pat, Suat; Balbağ, Zafer; Cenik, I.; Ekem, Naci; Okur, Salih; Vladoiu, Rodica; Musa, GeavitWe have developed a generic method for carbon deposition method for any substrates from methane pulsed plasma. The generic method has been developed for carbon deposition on the stainless steels substrates using pulsed methane plasma. Pulsed plasma was produced at atmospheric pressure methane gas and room temperatures. Methane plasma was generated using with 25kV, 25kHz pulsed power supply. Discharge current approximately 300 mA. Stainless steels probes hold in the 32mm from the methane plasma. Probes dimensions were phi=30mm, h=8mm and 4 mm.Conference Object Spin Polarized Tunneling in Large Area Mesas of Superconducting Bi 2sr2cacu2o8+δ for the Generation of the Thz Waves(Institute of Electrical and Electronics Engineers Inc., 2009) Türkoğlu, Fulya; Şimşek, Yılmaz; Köseoğlu, Hasan; Demirhan, Yasemin; Meriç Polster, Zeynep; Özyüzer, LütfiRectangular intrinsic Josephson junction mesa structures of superconducting Bi2Sr2CaCu2O8+delta (Bi2212) can be used as a source of continuous, coherent and polarized terahertz (THz) radiation. THz emitting mesas are below a certain underdoped level of Bi2212. They have small Josephson critical current in contrast to optimally doped and overdoped Bi2212. We deposited Au/Co/Au multilayer top of mesa and obtained small critical current from mesas fabricated by as-grown Bi2212 single crystals due to injection of spin polarized current. The spin injection eliminates adjustment of doping level for successful THz emission.Conference Object Reactive Ion Beam Etching of Superconducting Bi2212 by Ta/Pr and Pr'/ta/pr Masks for the Generation of Thz Waves(Institute of Electrical and Electronics Engineers Inc., 2009) Köseoğlu, Hasan; Türkoğlu, Fulya; Demirhan, Yasemin; Meriç Polster, Zeynep; Özyüzer, LütfiGeneration of powerful THz radiation from intrinsic Josephson Junctions (Ills) of Bi(2)Sr(2)CaCu(2)O(8+delta) (Bi2212) may require mesas with large lateral dimension. However, there are difficulties in fabrication of perfect rectangular mesas. Mesa lateral angles should be close to 90 degrees to obtain IJJs with same planar dimensions for synchronization of IJJs. Since thick photoresist (PR) layer shades the lateral dimension of mesa during ion beam etching, we patterned Ta/PR and PR'/Ta/PR masks on Bi2212 and used selective ion etching to overcome this problem. The reactive ion beam etchings have done with ion beam of Ar, N(2) and O(2) and we have obtained mesas about 1 mu m with lateral angle of approximately 50 to 75 degrees which is better than the mesas fabricated with single layer mask.Article Citation - WoS: 6Citation - Scopus: 6Variation of the Light and Period of the Magnetic Cataclysmic Variable Am Her(IOP Publishing, 2008) Kalomeni, Belinda; Yakut, KadriGround-based, long-term optic variability of AM Her, covering the period between 2003-2008, has been conducted to study the features seen in both low and high states of the system. Low-state analysis shows the presence of short-term, low-amplitude light variations of about 0.02-0.03 mag with a mean power time between 16 s and 226 s. Brightness variations on the order of 0.7-2 mag, which could be due to the stellar activity of the component in the system, are also detected. A total of 30 years' times of minimum light given in the literature are combined with nine times of minima obtained in this study. We represented the (observed-calculated) diagram by a parabolic curve and also by two broken lines. Under the assumption of a parabolic variation, we estimate an increase in period, dP/dt = 7.5(1.2) x 10(-9) days yr(-1), with a mass transfer rate of. M = 8(2) x 10(-9) M(circle dot) yr(-1), in agreement with the previous findings by a different method.Article Citation - WoS: 38Citation - Scopus: 40Influences of Deposition Time and Ph on Magnetic Nife Nanowires Fabrication(Elsevier, 2009) Atalay, Funda E.; Kaya, Harun; Atalay, Selcuk; Tarı, SüleymanIn this work, NiFe nanowires were grown into highly ordered porous anodic alumina oxide (AAO) templates by dc electrodeposition at various deposition times and pH values. During the deposition process some electrochemical bath parameters such as ion content, deposition voltage, and temperature of solution were kept constant. The morphological properties of the nanowire arrays were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the chemical composition was determined by examination of the energy dispersive X-ray (EDX) spectra, and the magnetic behavior of the arrays was determined by vibrating sample magnetometer (VSM). (C) 2008 Elsevier B.V. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 5Conductance Fluctuations in Undoped Hydrogenated Amorphous Silicon-Germanium Alloy Thin Films(Elsevier Ltd., 2002) Güneş, Mehmet; Johanson, Robert E.; Kasap, Safa O.; Yang, Jeffrey C.; Guha, SubhenduWe report coplanar conductance fluctuations of device quality, undoped hydrogenated amorphous silicon-germanium alloy thin films (a-SiGe:H) measured from 430 to 490 K. The a-SiGe:H alloys produce noise power spectra similar to coplanar undoped a-Si:H films in the same temperature range. The noise power spectrum S(n) does not fit a single 1/fα power law but rather has two distinct regions, each accurately fitted by a power law, but with different slopes. The low frequency slope α1 is similar to that observed in undoped a-Si:H films varying from 1.30 to 1.46 for different Ge concentrations and shows a slight temperature dependence. At higher frequencies, the slope α2 is less than unity and temperature independent but depends on the Ge content of the film. α2 decreases from 0.60 for no Ge (pure a-Si:H) to 0.15 for 40 at.% Ge. The noise power at lower frequencies increases and at higher frequencies decreases substantially as the temperature increases from 430 to 490 K. We infer that similar noise mechanisms are operating in undoped a-SiGe:H and a-Si:H films but that the Ge content is influencing the noise, particularly the slope at higher frequencies. In addition, the noise has the expected quadratic dependence on bias current and obeys Gaussian statistics.Article Citation - WoS: 150Citation - Scopus: 7Correlation of Tunneling Spectra in Bi2sr2cacu2o8+? With the Resonance Spin Excitation(American Physical Society, 2001) Zasadzinski, John F.; Özyüzer, Lütfi; Miyakawa, Nobuaki; Gray, Kenneth E.; Hinks, David G.; Kendziora, Christopher A.New break-junction tunneling data are reported in Bi2Sr2CaCu2O8+δ over a wide range of hole concentration from underdoped (Tc=74k) to optimal doped (Tc=95k) to overdoped (Tc=48k). The conductances exhibit sharp dips at a voltage, Ω/e, measured with respect to the superconducting gap. Clear trends are found such that the dip strength is maximum at optimal doping and that Ω scales as 4.9kTc over the entire doping range. These features link the dip to the resonance spin excitation and suggest quasiparticle interactions with this mode are important for superconductivity.Article Citation - WoS: 2Citation - Scopus: 2Scanning Probe Oxidation Lithography on Ta Thin Films(American Scientific Publishers, 2008) Okur, Salih; Büyükköse, Serkan; Tarı, SüleymanA Semi-Contact Scanning Probe Lithography Technique (SC-SPL) has been applied to create nano-oxide patterns on Ta thin films grown by DC magnetron sputtering method on SiO 2/Si substrates. The height and linewidth profiles of nano-oxide lines created by a conductive AFM tip on Ta film surfaces were measured as a function of applied voltage, oxidation time, humidity, and tip apex curvature. The AFM surface measurements show that the height of the oxides increases linearly with increasing voltage; but there was no oxide growth, when less than 4 V was applied even at 85% relative humidity. Electrical measurements were performed and the resistivities of the TaO x layer and Ta film were obtained as 5.76 × 10 8 and 1.4 × 10 5 Ohm-cm, respectively.