PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7645
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Article Citation - WoS: 7Citation - Scopus: 7Stable Ultra-Thin Cdte Crystal: a Robust Direct Gap Semiconductor(IOP Publishing Ltd., 2017) İyikanat, Fadıl; Akbalı, Barış; Kang, J.; Senger, Ramazan Tuğrul; Selamet, Yusuf; Şahin, HasanEmploying density functional theory based calculations, we investigate structural, vibrational and strain-dependent electronic properties of an ultra-thin CdTe crystal structure that can be derived from its bulk counterpart. It is found that this ultra-thin crystal has an 8-atom primitive unit cell with considerable surface reconstructions. Dynamic stability of the structure is predicted based on its calculated vibrational spectrum. Electronic band structure calculations reveal that both electrons and holes in single layer CdTe possess anisotropic in-plane masses and mobilities. Moreover, we show that the ultra-thin CdTe has some interesting electromechanical features, such as strain-dependent anisotropic variation of the band gap value, and its rapid increase under perpendicular compression. The direct band gap semiconducting nature of the ultra-thin CdTe crystal remains unchanged under all types of applied strain. With a robust and moderate direct band gap, single-layer CdTe is a promising material for nanoscale strain dependent device applications.Article Citation - WoS: 45Citation - Scopus: 47Search for Stopped Gluinos in Pp Collisions at ?s=7tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliThe results of the first search for long-lived gluinos produced in 7 TeV pp collisions at the CERN Large Hadron Collider are presented. The search looks for evidence of long-lived particles that stop in the CMS detector and decay in the quiescent periods between beam crossings. In a dataset with a peak instantaneous luminosity of 1×1032cm-2s-1, an integrated luminosity of 10pb-1, and a search interval corresponding to 62 hours of LHC operation, no significant excess above background was observed. Limits at the 95% confidence level on gluino pair production over 13 orders of magnitude of gluino lifetime are set. For a mass difference m g-mχ10>100GeV/c2, and assuming BR(g→gχ10)= 100%, mg<370GeV/c2 are excluded for lifetimes from 10μs to 1000 s. © 2010 The American Physical Society.Article Citation - WoS: 20Citation - Scopus: 19Search for Pair Production of Second-Generation Scalar Leptoquarks in Pp Collisions at ?s=7tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliA search for pair production of second-generation scalar leptoquarks in the final state with two muons and two jets is performed using proton-proton collision data at √s=7TeV collected by the CMS detector at the LHC. The data sample used corresponds to an integrated luminosity of 34pb-1. The number of observed events is in good agreement with the predictions from the standard model processes. An upper limit is set on the second-generation leptoquark cross section times β2 as a function of the leptoquark mass, and leptoquarks with masses below 394 GeV are excluded at a 95% confidence level for β=1, where β is the leptoquark branching fraction into a muon and a quark. These limits are the most stringent to date.© 2011 American Physical Society.Article Citation - WoS: 26Citation - Scopus: 28Search for Pair Production of First-Generation Scalar Leptoquarks in Pp Collisions at ?s=7tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliA search for pair production of first-generation scalar leptoquarks is performed in the final state containing two electrons and two jets using proton-proton collision data at √s=7TeV. The data sample used corresponds to an integrated luminosity of 33pb-1 collected with the CMS detector at the CERN LHC. The number of observed events is in good agreement with the predictions for the standard model background processes, and an upper limit is set on the leptoquark pair production cross section times β2 as a function of the leptoquark mass, where β is the branching fraction of the leptoquark decay to an electron and a quark. A 95% confidence level lower limit is set on the mass of a first-generation scalar leptoquark at 384 GeV for β=1, which is the most stringent direct limit to date. © 2011 American Physical Society.Article Citation - WoS: 58Citation - Scopus: 72Measurement of Dijet Angular Distributions and Search for Quark Compositeness in Pp Collisions at ?s=77tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliDijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at √s=7TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36pb-1. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Λ+=5.6TeV (Λ -=6.7TeV) for destructive (constructive) interference is obtained at the 95% confidence level. © 2011 American Physical Society.Article Citation - WoS: 44Citation - Scopus: 48Search for Supersymmetry in Pp Collisions at ?s=7tev in Events With Two Photons and Missing Transverse Energy(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliA search for supersymmetry in the context of general gauge-mediated breaking with the lightest neutralino as the next-to-lightest supersymmetric particle and the gravitino as the lightest is presented. The data sample corresponds to an integrated luminosity of 36pb-1 recorded by the CMS experiment at the LHC. The search is performed by using events containing two or more isolated photons, at least one hadronic jet, and significant missing transverse energy. No excess of events at high missing transverse energy is observed. Upper limits on the signal cross section for general gauge-mediated supersymmetry between 0.3 and 1.1 pb at the 95% confidence level are determined for a range of squark, gluino, and neutralino masses, excluding supersymmetry parameter space that was inaccessible to previous experiments. © 2011 American Physical Society.Article Citation - WoS: 86Citation - Scopus: 109Study of Z Boson Production in Pbpb Collisions at ?s Nn=2.76tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliA search for Z bosons in the μ+μ- decay channel has been performed in PbPb collisions at √sNN=2.76TeV with the CMS detector at the LHC, in a 7.2μb-1 data sample. The number of opposite-sign muon pairs observed in the 60-120GeV/c2 invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of [33.8±5.5(stat)±4.4(syst)]×10-8, in the |y|<2.0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions. © 2011 American Physical Society.Article Citation - WoS: 75Citation - Scopus: 80Search for Neutral Minimal Supersymmetric Standard Model Higgs Bosons Decaying To Tau Pairs in Pp Collisions at ?s=7tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliA search for neutral minimal supersymmetric standard model (MSSM) Higgs bosons in pp collisions at the LHC at a center-of-mass energy of 7 TeV is presented. The results are based on a data sample corresponding to an integrated luminosity of 36pb-1 recorded by the CMS experiment. The search uses decays of the Higgs bosons to tau pairs. No excess is observed in the tau-pair invariant-mass spectrum. The resulting upper limits on the Higgs boson production cross section times branching fraction to tau pairs, as a function of the pseudoscalar Higgs boson mass, yield stringent new bounds in the MSSM parameter space. © 2011 American Physical Society.Article Citation - WoS: 73Citation - Scopus: 74Measurement of the B0 Production Cross Section in Pp Collisions at √s=7tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliMeasurements of the differential production cross sections dσ/dpTB and dσ/dyB for B0 mesons produced in pp collisions at √s=7TeV are presented. The data set used was collected by the CMS experiment at the LHC and corresponds to an integrated luminosity of 40pb-1. The production cross section is measured from B0 meson decays reconstructed in the exclusive final state J/ψKS0, with the subsequent decays J/ψ→μ +μ- and KS0→π+π-. The total cross section for pTB>5GeV and <2.2 is measured to be 33.2±2.5±3.5μb, where the first uncertainty is statistical and the second is systematic. © 2011 American Physical Society.Article Citation - WoS: 243Citation - Scopus: 216Indications of Suppression of Excited? States in Pb-Pb Collisions at Snn2.76 Tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliA comparison of the relative yields of Υ resonances in the μ+μ- decay channel in Pb-Pb and pp collisions at a center-of-mass energy per nucleon pair of 2.76TeV is performed with data collected with the CMS detector at the LHC. Using muons of transverse momentum above 4GeV/c and pseudorapidity below 2.4, the double ratio of the Υ(2S) and Υ(3S) excited states to the Υ(1S) ground state in Pb-Pb and pp collisions, [Υ(2S+3S)/Υ(1S)]Pb-Pb/[Υ(2S+3S)/Υ(1S) ]pp, is found to be 0.31-0.15+0.19(stat)±0.03(syst). The probability to obtain the measured value, or lower, if the true double ratio is unity, is calculated to be less than 1%. © 2011 American Physical Society.