170 research outputs found

    Study of the radiation hardness of CsI(Tl) scintillation crystals

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    This paper is devoted to the study of a degradation of CsI(Tl)crystals scintillation characteristics under irradiation with gamma-quanta at the uniformly distributed absorbed dose up to 3700 rad. The sample set consisted of 25 crystals of 30 cm long having a truncated pyramid shape and 30 rectangular crystals of the same length. A large difference in the light output deterioration caused by the radiation was observed for the samples of the same shape. A substantial dependence of the average light output loss from the sample shape is seen as well. On the other hand, the crystals from the same ingot behave very similarly under irradiation

    Accelerating structure of 10 MEV electron linac

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    The calculation of the on-axis coupled the biperiodic 10 MeV electron accelerating structure is represented. The one-meter structure includes 19 accelerating cells, two of which are bunching cells. Two versions of RF feeding of accelerating structure 2.5 and 4.5 MW are considered. The peak beam current is 0.14 and 0.3 A for these versions. 44…49% of the injected current is accelerated. Shunt impedance is 74 MOhm/m with the 8 mm aperture diameter.Приведено результати розрахунку біперіодичної структури електронного прискорювача на енергію 10 МеВ зі зв'язком по осі. Метрова структура має 19 прискорюючих осередків, два з яких такі, що групують. Розглянуто два варіанти ВЧ-живлення структури потужністю 2,5 і 4,5 МВт. Амплітудне значення струму для цих варіантів дорівнюють 0.14 і 0.3 А, що забезпечує захоплення в процес прискорення 44...49% електронів. Структура з апертурою 8 мм має ефективний шунтовий опір 74 МОм/м.Приведены результаты расчета бипериодической ускоряющей структуры электронного ускорителя на энергию 10 МэВ со связью по оси. Метровая структура имеет 19 ускоряющих ячеек, две из которых группирующие. Рассмотрены два варианта ВЧ-питания ускоряющей структуры мощностью 2,5 и 4,5 МВт. Амплитудные значения тока для этих вариантов равны 0.14 и 0.3 А, что обеспечивает захват в процесс ускорения 44…49% электронов. Структура с апертурой 8 мм имеет эффективное шунтовое сопротивление 74 МОм/м

    Z6Z_6 symmetry, electroweak transition, and magnetic monopoles at high temperature

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    We consider the lattice realization of the Standard Model with an additional Z6Z_6 symmetry. Numerical simulations were performed on the asymmetric lattice, which corresponds to the finite temperature theory. Our choice of parameters corresponds to large Higgs masses (MH>90M_H > 90 Gev). The phase diagram was investigated and has been found to be different from that of the usual lattice realization of the Standard Model. It has been found, that the confinement-deconfinement phase transition lines for the SU(2) and SU(3) fields coincide. The transition line between Higgs and symmetric deconfinement parts of the phase diagram and the confinement-deconfinement transition line meet in a triple point. The transition between Higgs and symmetric parts of the phase diagram corresponds to the finite temperature electroweak transition/crossover. We see for the first time evidence that Nambu monopoles are condensed at T>TcT>T_c while at T<TcT<T_c their condensate vanishes.Comment: Latex, 14 page

    UV-VUV synchrotron radiation spectroscopy of NiWO₄

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    Photoluminescence and excitation spectra of microcrystalline and nanocrystalline nickel tungstate (NiWO₄) were measured using UV-VUV synchrotron radiation source. The origin of the bands is interpreted using comparative analysis with isostructural ZnWO₄ tungstate and based on the results of recent first-principles band structure calculations. The influence of the local atomic structure relaxation and of Ni²⁺ intra-ion d–d transitions on the photoluminescence band intensity are discussed

    Measurement of omega meson parameters in pi^+pi^-pi^0 decay mode with CMD-2

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    About 11 200 e^+e^- -> omega -> pi^+pi^-pi^0 events selected in the center of mass energy range from 760 to 810 MeV were used for the measurement of the \omega meson parameters. The following results have been obtained: sigma _{0}=(1457 \pm 23 \pm 19)nb, m_{\omega}=(782.71 \pm 0.07 \pm 0.04) MeV/c^{2}, \Gamma_{\omega}=(8.68 \pm 0.23 \pm 0.10) MeV, \Gamma_{e^+e^-}\cdot Br (\omega -> pi^+pi^-pi^0)= (0.528 \pm 0.012 \pm 0.007) \cdot 10^{-3} MeV.Comment: 8 pages, 4 figure

    Observation of KS0K_S^0 semileptonic decays with CMD-2 detector

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    The decay KS0πeνK_S^0 \to \pi e \nu has been observed by the CMD-2 detector at the e^+e^- collider VEPP-2M at Novosibirsk. Of 6 million produced KL0KS0K_L^0K_S^0 pairs, 75±1375 \pm 13 events of the KS0πeνK_S^0 \to \pi e \nu decay were selected. The corresponding branching ratio is B(KS0πeν)=(7.2±1.4)×104B(K_S^0 \to \pi e \nu)=(7.2 \pm 1.4)\times10^{-4}. This result is consistent with the evaluation of B(KS0πeν)B(K_S^0 \to \pi e \nu) from the KL0K_L^0 semileptonic rate and KS0K_S^0 lifetime assuming ΔS=ΔQ\Delta S=\Delta Q .Comment: 7 pages, 6 figures, LaTex2e. Submitted to Phys.Lett.

    Computation of the winding number diffusion rate due to the cosmological sphaleron

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    A detailed quantitative analysis of the transition process mediated by a sphaleron type non-Abelian gauge field configuration in a static Einstein universe is carried out. By examining spectra of the fluctuation operators and applying the zeta function regularization scheme, a closed analytical expression for the transition rate at the one-loop level is derived. This is a unique example of an exact solution for a sphaleron model in 3+13+1 spacetime dimensions.Comment: Some style corrections suggested by the referee are introduced (mainly in Sec.II), one reference added. To appear in Phys.Rev.D 29 pages, LaTeX, 3 Postscript figures, uses epsf.st

    Cross section of the reaction e+eπ+ππ+πe^+ e^- \to \pi^+\pi^-\pi^+\pi^- below 1 GeV at CMD-2

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    Using 3.07 pb1{pb}^{-1} of data collected in the energy range 0.60-0.97 GeV by CMD-2, about 150 events of the process \epm \to \pch have been selected. The energy dependence of the cross section agrees with the assumption of the a1(1260)πa_1(1260) \pi intermediate state which is dominant above 1 GeV. For the first time \fourpi events are observed at the ρ\rho meson energy. Under the assumption that all these events come from the ρ\rho meson decay, the value of the cross section at the ρ\rho meson peak corresponds to the following decay width: \Gamma(\rho^0 \to \fourpi) = (2.8 \pm 1.4 \pm 0.5) {keV} or to the branching ratio B(\rho^0 \to \fourpi) = (1.8 \pm 0.9 \pm 0.3) \cdot 10 ^{-5}.Comment: 15 pages, 5 figure

    The Seven-sphere and its Kac-Moody Algebra

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    We investigate the seven-sphere as a group-like manifold and its extension to a Kac-Moody-like algebra. Covariance properties and tensorial composition of spinors under S7S^7 are defined. The relation to Malcev algebras is established. The consequences for octonionic projective spaces are examined. Current algebras are formulated and their anomalies are derived, and shown to be unique (even regarding numerical coefficients) up to redefinitions of the currents. Nilpotency of the BRST operator is consistent with one particular expression in the class of (field-dependent) anomalies. A Sugawara construction is given.Comment: 22 pages. Macropackages used: phyzzx, epsf. Three epsf figure files appende
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