Use Of Cscl To Enhance The Glass Stability Range Of Tellurite Glasses For Er3+ Doped Optical Fiber Drawing

Tellurite glasses are important as a host of Er3+ ions because of their great solubility and because they present broader gain bandwidths than Er3+-doped silica, with promise to increase the bandwidth of communication systems. However, the small glass stability range (GSR) of tellurite glasses compromises the quality of the optical fibers. We show that the addition of CsCl to tellurite glasses can increase their GSR, making it easier to draw good quality optical fibers. CsCl acts as a network modifier in glass systems, weakening the network by forming Te-Cl bonds. We show that the thermal expansion coefficient mismatch is in the right direction for optical fiber fabrication purposes and that the Bi2O3 content can be used to control the refractive index of clad and core glasses. Single-mode and multi-mode Er3+-doped optical fibers were produced by the rod-in-tube method using highly homogeneous TeO2-ZnO-Li 2O-Bi2O3-CsCl glasses. Far infrared spectra of the glass samples exhibit absorption bands of the Te-Cl bond.6469Mori, A., Ohishi, Y., Sudo, S., Erbium-doped tellurite glass fibre laser and amplifier (1997) Electron. Lett, 33 (10), pp. 863-864Sekiya, T., Mochida, N., Ohtsuka, A., Tonokawa, M., Raman-spectra of Mo-TeO2 (M = Mg, Sr, Ba and Zn) glasses (1994) J. Non-Cryst. Solids, 168, pp. 1-2,106-114Bindra, K.S., Bookey, H.T., Kar, A.K., Wherrette, B.S., Liu, X., Jha, A., Nonlinear optical properties of chalcogenide glasses: Observation of multiphoton absorption (2001) Appl. Phys. Lett, 79 (13), pp. 1939-1941Wang, J.S., Vogel, E.M., Snitzer, E., Jackel, J.L., da Silva, V.L., Silbergerg, Y., 1.3 μm emission of neodymium and praseodymium in tellurite-based glasses (1994) J. Non-Cryst. Solids, 178, pp. 109-113Shen, S., Jha, A., Zhang, E., Wilson, S.J., Compositional effects and spectroscopy of rare earths (Er3+, Tm3+, and Nd 3+) in tellurite glasses (2002) C.R. Chim, 5 (12), pp. 921-938Yamada, M., Mori, A., Ono, H., Kobayashi, K., Kanamori, T., Ohishi, Y., Broadband and gain-flattened Er3+-doped tellurite fibre amplifier constructed using a gain equaliser (1998) Electron. Lett, 34 (4), pp. 370-371Mori, K., Kobayashi, M., Yamada, T., Kanamori, K., Oikawa, Y., Nishida, Y., Ohishi, Y., Low noise broadband tellurite-based Er3+-doped fibre amplifiers (1998) Electron. Lett, 34 (9), pp. 887-888Snitzer, E., Vogel, E.M., Wang, J.S., Tellurite glass and fiber amplifier (1993), US Patent 5,251,062Aitken, B.G., Ellison, A.J.G., Tellurite glasses and optical components (2001), US Patent 6,194,334Ding, Y., Jiang, S., Hwang, B.C., Luo, T., Peyghambarian, N., Himei, Y., Ito, T., Miura, Y., Spectral properties of erbium-doped lead halotellurite glasses for 1.5 μm broadband amplification (2000) Opt. Mater, 15 (2), pp. 123-130Keiser, G., (1999) Optical Fiber Communication, , Mac-Graw Hill, New YorkBarbosa, L.C., Cesar, C.L., Mazali, I.O., Barbosa, L.C., Alves, O.L., Spectroscopic and thermal properties of Ga2S 3-Na2S-CsCl glasses (2006) J. Am. Ceram. Soc, 89 (3), pp. 1037-1041Mazali, I.O., Barbosa, L.C., Alves, O.L., Preparation and characterization of new niobophosphate glasses in the Li2O-Nb 2O5-CaO-P2O5 system (2004) J. Mater. Sci, 39 (6), pp. 1987-1995El-Kheshen, A.A., Zawrah, M.F., Sinterability, microstructure and properties of glass/ceramic composite (2003) Ceram. Int, 29 (3), pp. 251-257A. Hruby, Evaluation of glass-forming tendency by means of DTA, Czech. J. Phys. B, B22 1187-& (1972)Burger, H., Vogel, W., Kozhukharov, V., IR transmission and properties of glasses in the TeO2-[RNOM, RNXM, RN(SO4)M, RN(PO3)M and B2O3] systems (1985) Infr. Phys, 25 (1-2), pp. 395-409Higazy, A.A., Bridge, B., Infrared-Spectra of the vitreous system CO 3O4-P2O5 and their interpretation (1985) Jour. Mat. Sci, 20 (7), pp. 2345-2358Bridge, B., Round, R., Computation of the bulk modulus of the high temperature ceramic superconductor YBa2Cu3O7-X from unit-cell data (1988) Jour. Mat. Sci. Lett, 7 (1), pp. 63-65Reynoso, V.C.S., Barbosa, L.C., Alves, O.L., Aranha, N., César, C.L., Preparation and characterization of heavy-metal oxide glasses - Bi2O3-PbO-B2O3-GeO 2 system (1994) J. Mater. Chem, 4 (4), pp. 529-532Canale, J.E., Condrate, R.A., Nassau, K., Cornilsen, B.C., Characterization of various glasses in the binary PbO-GeO2 and Bi2O3-GeO2 systems (1986) J. Can. Ceram. Soc, 55, pp. 50-56Adams, D.M., Lloyd, M.H., Far-Infrared reflectance spectra of some hexachlorotellurates and other hexachlorometallates (1971) Jour. Chem. Soc. A.-Inorganic Phys Theor, 7, p. 878Gloge, D., Weakly guiding fibers (1971) Appl. Opt, , 10 [10] 2252-

Green function techniques in the treatment of quantum transport at the molecular scale

The theoretical investigation of charge (and spin) transport at nanometer length scales requires the use of advanced and powerful techniques able to deal with the dynamical properties of the relevant physical systems, to explicitly include out-of-equilibrium situations typical for electrical/heat transport as well as to take into account interaction effects in a systematic way. Equilibrium Green function techniques and their extension to non-equilibrium situations via the Keldysh formalism build one of the pillars of current state-of-the-art approaches to quantum transport which have been implemented in both model Hamiltonian formulations and first-principle methodologies. We offer a tutorial overview of the applications of Green functions to deal with some fundamental aspects of charge transport at the nanoscale, mainly focusing on applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references, submitted to Springer series "Lecture Notes in Physics

Measurements of long-range near-side angular correlations in sNN=5\sqrt{s_{\text{NN}}}=5TeV proton-lead collisions in the forward region

Two-particle angular correlations are studied in proton-lead collisions at a nucleon-nucleon centre-of-mass energy of $\sqrt{s_{\text{NN}}}=5$TeV, collected with the LHCb detector at the LHC. The analysis is based on data recorded in two beam configurations, in which either the direction of the proton or that of the lead ion is analysed. The correlations are measured in the laboratory system as a function of relative pseudorapidity, $\Delta\eta$, and relative azimuthal angle, $\Delta\phi$, for events in different classes of event activity and for different bins of particle transverse momentum. In high-activity events a long-range correlation on the near side, $\Delta\phi \approx 0$, is observed in the pseudorapidity range $2.0<\eta<4.9$. This measurement of long-range correlations on the near side in proton-lead collisions extends previous observations into the forward region up to $\eta=4.9$. The correlation increases with growing event activity and is found to be more pronounced in the direction of the lead beam. However, the correlation in the direction of the lead and proton beams are found to be compatible when comparing events with similar absolute activity in the direction analysed.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-040.htm

Evidence for the strangeness-changing weak decay Ξb−→Λb0π−\Xi_b^-\to\Lambda_b^0\pi^-

Using a $pp$ collision data sample corresponding to an integrated luminosity of 3.0~fb$^{-1}$, collected by the LHCb detector, we present the first search for the strangeness-changing weak decay $\Xi_b^-\to\Lambda_b^0\pi^-$. No $b$ hadron decay of this type has been seen before. A signal for this decay, corresponding to a significance of 3.2 standard deviations, is reported. The relative rate is measured to be ${{f_{\Xi_b^-}}\over{f_{\Lambda_b^0}}}{\cal{B}}(\Xi_b^-\to\Lambda_b^0\pi^-) = (5.7\pm1.8^{+0.8}_{-0.9})\times10^{-4}$, where $f_{\Xi_b^-}$ and $f_{\Lambda_b^0}$ are the $b\to\Xi_b^-$ and $b\to\Lambda_b^0$ fragmentation fractions, and ${\cal{B}}(\Xi_b^-\to\Lambda_b^0\pi^-)$ is the branching fraction. Assuming $f_{\Xi_b^-}/f_{\Lambda_b^0}$ is bounded between 0.1 and 0.3, the branching fraction ${\cal{B}}(\Xi_b^-\to\Lambda_b^0\pi^-)$ would lie in the range from $(0.57\pm0.21)\%$ to $(0.19\pm0.07)\%$.Comment: 7 pages, 2 figures, All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-047.htm

Study of the production of Λb0\Lambda_b^0 and B‾0\overline{B}^0 hadrons in pppp collisions and first measurement of the Λb0→J/ψpK−\Lambda_b^0\rightarrow J/\psi pK^- branching fraction

The product of the $\Lambda_b^0$ ($\overline{B}^0$) differential production cross-section and the branching fraction of the decay $\Lambda_b^0\rightarrow J/\psi pK^-$ ($\overline{B}^0\rightarrow J/\psi\overline{K}^*(892)^0$) is measured as a function of the beauty hadron transverse momentum, $p_{\rm T}$, and rapidity, $y$. The kinematic region of the measurements is $p_{\rm T}<20~{\rm GeV}/c$ and $2.0<y<4.5$. The measurements use a data sample corresponding to an integrated luminosity of $3~{\rm fb}^{-1}$ collected by the LHCb detector in $pp$ collisions at centre-of-mass energies $\sqrt{s}=7~{\rm TeV}$ in 2011 and $\sqrt{s}=8~{\rm TeV}$ in 2012. Based on previous LHCb results of the fragmentation fraction ratio, $f_{\Lambda_B^0}/f_d$, the branching fraction of the decay $\Lambda_b^0\rightarrow J/\psi pK^-$ is measured to be \begin{equation*} \mathcal{B}(\Lambda_b^0\rightarrow J/\psi pK^-)= (3.17\pm0.04\pm0.07\pm0.34^{+0.45}_{-0.28})\times10^{-4}, \end{equation*} where the first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay $\overline{B}^0\rightarrow J/\psi\overline{K}^*(892)^0$, and the fourth is due to the knowledge of $f_{\Lambda_b^0}/f_d$. The sum of the asymmetries in the production and decay between $\Lambda_b^0$ and $\overline{\Lambda}_b^0$ is also measured as a function of $p_{\rm T}$ and $y$. The previously published branching fraction of $\Lambda_b^0\rightarrow J/\psi p\pi^-$, relative to that of $\Lambda_b^0\rightarrow J/\psi pK^-$, is updated. The branching fractions of $\Lambda_b^0\rightarrow P_c^+(\rightarrow J/\psi p)K^-$ are determined.Comment: 29 pages, 19figures. All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-032.htm

BB flavour tagging using charm decays at the LHCb experiment

An algorithm is described for tagging the flavour content at production of neutral $B$ mesons in the LHCb experiment. The algorithm exploits the correlation of the flavour of a $B$ meson with the charge of a reconstructed secondary charm hadron from the decay of the other $b$ hadron produced in the proton-proton collision. Charm hadron candidates are identified in a number of fully or partially reconstructed Cabibbo-favoured decay modes. The algorithm is calibrated on the self-tagged decay modes $B^+ \to J/\psi \, K^+$ and $B^0 \to J/\psi \, K^{*0}$ using $3.0\mathrm{\,fb}^{-1}$ of data collected by the LHCb experiment at $pp$ centre-of-mass energies of $7\mathrm{\,TeV}$ and $8\mathrm{\,TeV}$. Its tagging power on these samples of $B \to J/\psi \, X$ decays is $(0.30 \pm 0.01 \pm 0.01) \%$.Comment: All figures and tables, along with any supplementary material and additional information, are available at http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-027.htm

Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters

Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV

The Lambda(b) differential production cross section and the cross section ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Lambda(b) decays reconstructed in the exclusive final state J/Psi Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and Lambda to proton pion, using a data sample corresponding to an integrated luminosity of 1.9 inverse femtobarns. The product of the cross section times the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls faster than that of b mesons. The measured value of the cross section times the branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06 +/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are statistical and systematic, respectively.Comment: Submitted to Physics Letters