Browsing by Author "Tapan, Ilhan"

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    Influence of neutrons on signal fluctuations for APD structures
    (Elsevier, 2013-08-01) Kılıç, Adnan; Koçak, Fatma; Piliçer, Ercan; Tapan, Ilhan; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Anabilim Dalı.; 0000-0002-4756-9988; AAH-8769-2021; AAE-3350-2022; 57210230921; 15843834900; 15843878300; 8905787000; European Phys Soc (EPS)
    Silicon Avalanche Photo-diodes (APDs) working in proportional were chosen as a readout device for the PbWO4 crystals in the barrel of the CMS Electromagnetic Calorimeter (ECAL). During 10 years of operation, the CMS ECAL will be exposed to 2 x 10(13) neutrons/cm(2) under a severe radiation environment. In this study, we studied on the effect of photo-statistical fluctuations from those of neutrons by using Geant4 toolkit.
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    Observation of the isospin-violating decay J/psi -> phi pi(0)f(0) (980)
    (American Physical Society, 2015-07-17) Tapan, Ilhan; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; CCD-9486-2022; 8905787000
    Using a sample of 1.31 x 10(9) J/psi events collected with the BESIII detector at the BEPCII collider, the decays J/psi -> phi pi(+)pi(-)pi(0) and J/psi -> phi pi(0)pi(0)pi(0) are investigated. The isospin- violating decay J/psi -> phi pi(0)f(0)(980) with f(0)(980)-> pi pi is observed for the first time. The width of the f(0)(980) obtained from the dipion mass spectrum is found to be much smaller than the world average value. In the pi(0)f(0)(980) mass spectrum, there is evidence of f(1)(1285) production. By studying the decay J/psi ->eta', the branching fractions of eta' -> pi(+)pi(-)pi(0) and eta' -> pi(0)pi(0)pi(0), as well as their ratio, are also measured.
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    Observation of η′ → ωe+e-
    (Amer physical, 2015-10-14) Tapan, Ilhan; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; CCD-9486-2022; 8905787000
    Based on a sample of eta' mesons produced in the radiative decay J/psi -> gamma eta' in 1.31 x 10(9) J/psi events collected with the BESIII detector, the decay eta' -> omega e(+)e(-) is observed for the first time, with a statistical significance of 8 sigma. The branching fraction is measured to be B(eta' -> omega e(+)e(-)) = (1.97 +/- 0.34(stat) +/- 0.17(syst)) x 10(-4), which is in agreement with theoretical predictions. The branching fraction of eta' -> omega gamma is also measured to be (2.55 +/- 0.03(stat) +/- 0.16(syst)) x 10(-2), which is the most precise measurement to date, and the relative branching fraction B(eta' -> omega e(+)e(-))/B(eta' -> omega gamma) is determined to be (7.71 +/- 1.34(stat) +/- 0.54(syst)) x 10(-3).
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    Precision measurement of the D*0 decay branching fractions
    (Amer physical, 2015-02-06) Tapan, Ilhan; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; CCD-9486-2022; 8905787000
    Using 482 pb(-1) of data taken at root s = 4.009 GeV, we measure the branching fractions of the decays of D*(0) into D-0 pi(0) and D-0 gamma to be B(D*(0) -> D-0 pi(0)) = (65.5 +/- 0.8 +/- 0.5)% and B(D*(0) -> D0 gamma) = (34.5 +/- 0.8 +/- 0.5)%, respectively, by assuming that the D*(0) decays only into these two modes. The ratio of the two branching fractions is B(D*(0) -> D-0 pi(0))/B(D*(0) -> D-0 gamma) = 1.90 +/- 0.07 +/- 0.05, which is independent of the assumption made above. The first uncertainties are statistical and the second ones systematic. The precision is improved by a factor of 3 compared to the present world average values.
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    Search for the isospin violating decay Y(4260)→ J/ψηπ0
    (Amer physical soc, 2015-07-17) Tapan, Ilhan; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Bölümü.; CCD-9486-2022; 8905787000
    Using data samples collected at center-of-mass energies of root s = 4.009, 4.226, 4.257, 4.358, 4.416, and 4.599 GeV with the BESIII detector operating at the BEPCII storage ring, we search for the isospin violating decay Y(4260)-> J/psi eta pi(0). No signal is observed, and upper limits on the cross section sigma(e(+)e(-) -> J/psi eta pi(0)) at the 90% confidence level are determined to be 3.6, 1.7, 2.4, 1.4, 0.9, and 1.9 pb, respectively.