170 research outputs found
Study of the radiation hardness of CsI(Tl) scintillation crystals
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
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
symmetry, electroweak transition, and magnetic monopoles at high temperature
We consider the lattice realization of the Standard Model with an additional
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 ( 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
while at their condensate vanishes.Comment: Latex, 14 page
UV-VUV synchrotron radiation spectroscopy of NiWO₄
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
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 semileptonic decays with CMD-2 detector
The decay has been observed by the CMD-2 detector at
the e^+e^- collider VEPP-2M at Novosibirsk. Of 6 million produced
pairs, events of the decay were selected. The
corresponding branching ratio is . This result is consistent with the evaluation of from the semileptonic rate and lifetime
assuming .Comment: 7 pages, 6 figures, LaTex2e. Submitted to Phys.Lett.
Study of the process e+e- to pi+pi-pi+pi-pi0 with CMD-2 detector
The process e+e- to pi+ pi- pi+ pi- pi0 has been studied in the center of
mass energy range 1280 -- 1380 MeV using 3.0 1/pb of data collected with the
CMD-2 detector in Novosibirsk. Analysis shows that the cross section of the
five pion production is dominated by the contributions of the eta pi+pi- and
omega pi+pi- intermediate states.Comment: 8 pages, 3 figure. Submitted to Phys. Lett.
Computation of the winding number diffusion rate due to the cosmological sphaleron
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 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 below 1 GeV at CMD-2
Using 3.07 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
intermediate state which is dominant above 1 GeV. For the first
time \fourpi events are observed at the meson energy. Under the
assumption that all these events come from the meson decay, the value of
the cross section at the 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
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 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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