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1.
A search for double electron capture of 106Cd was performed at the Modane Underground Laboratory (4800 m w.e.) using a low-background and high-sensitivity multidetector
spectrometer TGV-2 (Telescope Germanium Vertical). New limits on β
+/EC, EC/EC decays of 106Cd were obtained from preliminary calculations of experimental data accumulated for 4800 h of measurement of 10 g of 106Cd with enrichment of 75%. They are
> 9.1 × 10 18 yr,
> 1.9 × 10 19 yr for transitions to the first 2 +, 511.9 keV excited state of 106Pd, and
> 1.3 × 10 19 yr,
> 6.2 × 10 19 yr for transitions to the ground 0 + state of 106Pd. All limits are given at 90% C.L.
The text was submitted by the authors in English. 相似文献
2.
Neutrino interactions with two muons in the final state have been studied using the Fermilab narrow band beam. A sample of 18 v μ like sign dimuon events with P μ>9 GeV/c yields 6.6±4.8 events after backgroud subtraction and a prompt rate of (1.0±0.7)×10 ?4 per single muon event. The kinematics of these events are compared with those of the non-prompt sources. A total of 437 v μ and 31 \(\bar v_\mu \) opposite sign dimuon events with P μ>4.3 GeV/c are used to measure the strange quark content of the nucleon: \(\kappa = {{2s} \mathord{\left/ {\vphantom {{2s} {\left( {\bar u + \bar d} \right) = 0.52_{ - 0.15}^{ + 0.17} \left( {or\eta _s \frac{{2s}}{{u + d}} = 0.075 \pm 0.019} \right) for 100< E_v< 230 GeV\left( {\left\langle {Q^2 } \right\rangle = {{23 GeV^2 } \mathord{\left/ {\vphantom {{23 GeV^2 } {c^2 }}} \right. \kern-0em} {c^2 }}} \right)}}} \right. \kern-0em} {\left( {\bar u + \bar d} \right) = 0.52_{ - 0.15}^{ + 0.17} \left( {or\eta _s \frac{{2s}}{{u + d}} = 0.075 \pm 0.019} \right) for 100< E_v< 230 GeV\left( {\left\langle {Q^2 } \right\rangle = {{23 GeV^2 } \mathord{\left/ {\vphantom {{23 GeV^2 } {c^2 }}} \right. \kern-0em} {c^2 }}} \right)}}\) using a charm semileptonic branching ratio of (10.9±1.4)% extracted from measurements in e + e ? collisions and neutrino emulsion data. 相似文献
4.
Al, F-doped new perovskite lithium ion conductors ( x=0.11) have been prepared by solid state reaction. It is found that a pure perovskite-structured phase with space group of P4mm(99) exits in the composition range of 0< y≤0.10. The sample with y=0.02 possesses the highest ionic conductivity of 1.06×10 −3 S/cm at room temperature, and its decomposing voltage is 2.3 V. The factors affecting the conductivity of this system are discussed. 相似文献
5.
To date, the fastest lithium ion-conducting solid electrolytes known are the perovskite-type ABO3 oxide, with A = Li, La and B = Ti, lithium lanthanum titanate (LLTO)
Li3x La( 2 \mathord | / |
\vphantom 2 3 3 ) - x [¯]( 1 \mathord | / |
\vphantom 1 3 3 ) - x TiO3 {\rm Li}_{3x} {\rm La}_{\left( {{2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-\nulldelimiterspace} 3}} \right) - x} \Box_{\left( {{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}} \right) - x} {\rm TiO}_3 and its structurally related materials. In this formula, [¯]\Box represents the vacancy. These materials have attracted much attention due to their application in lithium ion batteries used
as energy sources in microelectronic and information technologies. In addition to the well-established simple cubic, tetragonal
and orthorhombic perovskite type distorted cell structures, the hexagonal unit cell was reported in a recent study for Li0.5 La0.5 TiO3 − δ
, ( 0 £ d £ 0.06 )\left( {0 \le \delta \le 0.06} \right). We investigated the ionic conductivity in hexagonal La0.5 Li0.5 TiO3{\rm La}_{0.5} {\rm Li}_{0.5}\- {\rm TiO}_3 by molecular dynamics. We confirmed that ionic conductivity in this compound is due to the motion of lithium ions. We show
that both Arrhenius and Vogel–Tamman–Fulcher-type relationships could be used to express the high-temperature conductivity
of this compound. From our results, hexagonal LLTO exhibits almost 1.7–1.9 ×10 − 3 S cm − 1 at room temperature. Thus, due to its high ionic conductivity, this compound is expected to show some advantages in comparison
with the best conductors of this family, for usual applications of ionic conductors. 相似文献
6.
Under a 980 nm laser pumping, quenching of green upconversion (UC) emission accompanied with enhancement of red UC emission
observed was dominated by the energy back-transfer (EBT) process in Er 3+ and Yb 3+ co-doped PbTiO 3, BaTiO 3, and SrTiO 3 polycrystalline powders. The efficiency of the EBT process depends not only on Yb 3+ concentration but also on level match of the doped Er 3+ and Yb 3+ ions caused by the crystal fields with different symmetries. Our UC emission spectra and X-ray diffraction confirm that the
centrosymmetric crystal field arising from reducing tetragonality causes level match of transition of Er 3+ and of Yb 3+. This level match is responsible for enhancing red UC emission. 相似文献
7.
We have calculated analytically the superheating field H
sh
for bulk superconductors, correct to second order in . We find
, which agrees well with numerical computations for <0.5. The surface order parameter is
, and the penetration depth is
. 相似文献
8.
Several new levels including two isomeric states have been established in 134Ba. Spin and parity assignments of 10 + and 5 ? are proposed for the isomers. The former may have a \(\left( {vh_{1 1/2} } \right)_{10^ + } \) configuration while the latter may be either \((vs_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-0em} 2}} vh_{{{11} \mathord{\left/ {\vphantom {{11} 2}} \right. \kern-0em} 2}} )_{5 - } \) or \(\left( {vd_{3/2} vh_{1 1/2} } \right)_{5^ - } \) . 相似文献
9.
Using older compilations and recent data the (n, p) cross sections for neutron energies between 14 and 15 MeV have been collected and revised critically. The experimental data can be represented phenomenologically by the formula $$\log _{10} ({{\sigma _{np} } \mathord{\left/ {\vphantom {{\sigma _{np} } {mb}}} \right. \kern-\nulldelimiterspace} {mb}}) = 0.2 + 0.4A^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} - 4.6{{(N - Z)} \mathord{\left/ {\vphantom {{(N - Z)} {A^{{2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-\nulldelimiterspace} 3}} }}} \right. \kern-\nulldelimiterspace} {A^{{2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-\nulldelimiterspace} 3}} }}$$ . The compound part of the (n, p) reactions is described by a statistical model; the direct reactions are taken into account semiempirically. 相似文献
11.
The Mainz neutrino-mass experiment investigates the endpoint region of the tritium β-decay spectrum with a MAC-E spectrometer to determine the mass of the electron antineutrino. By the recent upgrade, the former problem of dewetting T 2 films has been solved, and the signal-to-background ratio was improved by a factor of 10. The latest measurement leads to $m_\nu ^2 = - 3.7 \pm 5.3(stat.) \pm 2.1(syst.){{eV^2 } \mathord{\left/ {\vphantom {{eV^2 } {c^4 }}} \right. \kern-0em} {c^4 }}$ , from which an upper limit of $m_\nu < 2.8{{eV^2 } \mathord{\left/ {\vphantom {{eV^2 } {c^2 }}} \right. \kern-0em} {c^2 }}(95\% C.L.)$ is derived. Some indication for the anomaly, reported by the Troitsk group, was found, but its postulated half-year period is contradicted by our data. To push the sensitivity on the neutrino mass below 1 eV/ c 2, a new larger MAC-E spectrometer is proposed. Besides its integrating mode, it could run in a new nonintegration operation MAC-E-TOF mode. 相似文献
12.
At T=0 a perfect Mössbauer line has natural line width Γ=?/τ n . However, with rising temperature the width increases. The reason of the line broadening is the second order Doppler effect which causes a stochastic frequency modulation of the γ-radiation, reflecting the thermal motion of the Mössbauer atom. Following Josephson in treating the second order Doppler shift as a mass change ΔM=E n/c 2 of the γ-emitting atom caused by the loss of nuclear excitation energy E n , and using the well known relaxation formalism for calculating the γ-frequency spectrum, the line broadening Δ Γ is evaluated within the framework of harmonic lattice theory. For a parabolic lattice frequency spectrum with Debye-temperature Θ one obtains $$\Delta {\Gamma \mathord{\left/ {\vphantom {\Gamma \Gamma }} \right. \kern-\nulldelimiterspace} \Gamma } = \left( {{{\tau _n } \mathord{\left/ {\vphantom {{\tau _n } {\tau _c }}} \right. \kern-\nulldelimiterspace} {\tau _c }}} \right) \cdot \left( {{{E_n } \mathord{\left/ {\vphantom {{E_n } {Mc^2 }}} \right. \kern-\nulldelimiterspace} {Mc^2 }}} \right) \cdot F\left( {{T \mathord{\left/ {\vphantom {T \Theta }} \right. \kern-\nulldelimiterspace} \Theta }} \right),where\tau _c = {{\rlap{--} h} \mathord{\left/ {\vphantom {{\rlap{--} h} k}} \right. \kern-\nulldelimiterspace} k}\Theta $$ is the correlation time of the lattice vibrations. The function F(T/Θ) may be expanded in powers of T/Θ, yielding $$F\left( {{T \mathord{\left/ {\vphantom {T \Theta }} \right. \kern-\nulldelimiterspace} \Theta }} \right) = 9720\pi \left( {{T \mathord{\left/ {\vphantom {T \Theta }} \right. \kern-\nulldelimiterspace} \Theta }} \right)^7 forT<< \Theta $$ and $$F\left( {{T \mathord{\left/ {\vphantom {T \Theta }} \right. \kern-\nulldelimiterspace} \Theta }} \right) = 2.7\pi \left( {{T \mathord{\left/ {\vphantom {T \Theta }} \right. \kern-\nulldelimiterspace} \Theta }} \right)^2 forT > > \Theta $$ , respectively. Although unavoidable, the line broadening is obviously too small to be observable by means of the present experimental technique. 相似文献
13.
An electric Molecular-Beam-Resonance-Spectrometer has been used to measure simultanously the Zeeman- and Stark-effect splitting of the hyperfine structure of 39K 19 F. Electric four pole lenses served as focusing and refocusing fields of the spectrometer. A homogenous magnetic field (Zeeman field) was superimposed to the electric field (Stark field) in the transition region of the apparatus. The observed ( Δm J =±1)-transitions were induced electrically. Completely resolved spectra of KF in the J=1 rotational state have been measured. The obtained quantities are: The electric dipolmoment μ e l of the molecul for v=0,1 and 2; the rotational magnetic dipolmoment μ J for v=0,1; the difference of the magnetic shielding (σ ⊥ ? σ ∥) by the electrons of both nuclei as well as the difference of the molecular susceptibility (ξ ⊥ ? ξ ∥). The numerical values are $$\begin{array}{*{20}c} {\mu _{e1} = 8,585(4)deb,} \\ {\frac{{(\mu _{e1} )_{\upsilon = 1} }}{{(\mu _{e1} )_{\upsilon = 0} }} = 1,0080,} \\ {{{\mu _J } \mathord{\left/ {\vphantom {{\mu _J } J}} \right. \kern-\nulldelimiterspace} J} = ( - )2352(10) \cdot 10^{ - 6} \mu _B ,} \\ {(\sigma _ \bot - \sigma _\parallel )F = ( - )2,19(9) \cdot 10^{ - 4} ,} \\ {(\sigma _ \bot - \sigma _\parallel )K = ( - )12(9) \cdot 10^{ - 4} ,} \\ {(\xi _ \bot - \xi _\parallel ) = 3 (1) \cdot 10^{ - 30} {{erg} \mathord{\left/ {\vphantom {{erg} {Gau\beta ^2 }}} \right. \kern-\nulldelimiterspace} {Gau\beta ^2 }}} \\ \end{array} $$ 相似文献
14.
Static finite energy solutions of the field theory described by
are obtained. Some of the interesting features of this model are (1) the mass-square here is positive unlike in the λφ 4 Higg's model, (2) the potential has three global minimas, (3) the spectrum is bounded from below unlike in the λφ 4 theory with λ<0, (4) there are two kink and two antikink solutions, (5) unlike sine-Gordon and λφ 4 models here there are two particles with masses m and 2 m. Nontopological finite energy solutions have also been obtained for gφ
6 field theory with g < 3λ
2 / 16 m
2. 相似文献
15.
The conductivity of carbon films grown by polymethylphenylsiloxane vapor decomposition in stimulated dc discharge plasma was
studied. It is found that the Mott hopping conductivity $
\sigma \left( T \right) = \sigma _0 \left( T \right)\exp \left\{ { - \frac{{T_0 }}
{T}^{{1 \mathord{\left/
{\vphantom {1 4}} \right.
\kern-\nulldelimiterspace} 4}} } \right\}
$
\sigma \left( T \right) = \sigma _0 \left( T \right)\exp \left\{ { - \frac{{T_0 }}
{T}^{{1 \mathord{\left/
{\vphantom {1 4}} \right.
\kern-\nulldelimiterspace} 4}} } \right\}
is characteristic of the samples under study in the temperature range of 80–400 K in the electric field E to 5 · 10 4 V/cm. An analysis of the pre-exponential factor σ
0( T) = σ
00( T
0) T
α allowed the conclusion that the hopping transport is most adequately described in the model with the exponential energy dependence
of the density of localized states for which α = −1/2 and the universal relation ln σ
00 − T
01/4 0 is valid, which is satisfied in the range where the parameter σ
00 varies by eight orders of magnitude. 相似文献
16.
We discuss the discrete spectrum of the operator $$H_K (c) = \left[ { - \hbar ^2 c^2 \Delta + m^2 c^4 } \right]^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} - \sum\limits_{k = 1}^K {Z_k e^2 \left| {x - R_k } \right|^{ - 1} } $$ . More specifically, we study 1) the behaviour of the eigenvalues when the internuclear distances contract, 2) the existence of a c-independent lower bound for H K ( c)? mc 2, 3) the nonrelativistic limit of the eigenvalues of H K ( c)? mc 2. 相似文献
17.
The structures of all three phases of the Rb 2KInF 6 crystal have been determined from the experimental X-ray diffraction data for the powder sample. The refinement of the profile
and structural parameters has been carried out by the technique implemented in the DDM program, which minimizes the differences
between the derivatives of the calculated and measured X-ray intensities over the entire profile of the X-ray diffraction
pattern. The results obtained have been discussed using the group-theoretical analysis of the complete order-parameter condensate,
which takes into account the critical and noncritical atomic displacements and permits the interpretation of the experimental
data obtained previously. It has been reliably established that the sequence of changes in the symmetry during phase transitions
in Rb 2KInF 6 can be represented as $
Fm\bar 3m\xrightarrow[{0,0,\phi }]{{11 - 9\left( {\Gamma _4^ + } \right)}}{{I114} \mathord{\left/
{\vphantom {{I114} {m\xrightarrow[{\left( {\psi ,\phi ,\phi } \right)}]{{11 - 9\left( {\Gamma _4^ + } \right) \oplus 10 - 3\left( {X_3^ + } \right)}}{{P12_1 } \mathord{\left/
{\vphantom {{P12_1 } {n1}}} \right.
\kern-\nulldelimiterspace} {n1}}}}} \right.
\kern-\nulldelimiterspace} {m\xrightarrow[{\left( {\psi ,\phi ,\phi } \right)}]{{11 - 9\left( {\Gamma _4^ + } \right) \oplus 10 - 3\left( {X_3^ + } \right)}}{{P12_1 } \mathord{\left/
{\vphantom {{P12_1 } {n1}}} \right.
\kern-\nulldelimiterspace} {n1}}}}
$
Fm\bar 3m\xrightarrow[{0,0,\phi }]{{11 - 9\left( {\Gamma _4^ + } \right)}}{{I114} \mathord{\left/
{\vphantom {{I114} {m\xrightarrow[{\left( {\psi ,\phi ,\phi } \right)}]{{11 - 9\left( {\Gamma _4^ + } \right) \oplus 10 - 3\left( {X_3^ + } \right)}}{{P12_1 } \mathord{\left/
{\vphantom {{P12_1 } {n1}}} \right.
\kern-\nulldelimiterspace} {n1}}}}} \right.
\kern-\nulldelimiterspace} {m\xrightarrow[{\left( {\psi ,\phi ,\phi } \right)}]{{11 - 9\left( {\Gamma _4^ + } \right) \oplus 10 - 3\left( {X_3^ + } \right)}}{{P12_1 } \mathord{\left/
{\vphantom {{P12_1 } {n1}}} \right.
\kern-\nulldelimiterspace} {n1}}}}
. 相似文献
18.
The Weber potential energy U for charges q and q' separated by the distance R is U = (qq'/R)[1 – (dR/dt) 2/2c 2]. If this potential arises from a finite velocity c of energy transfer Q', where the retarded rate of transfer from q' to q is dQ(t-R/c)/dt = Q'[1 – (dR/dt)/c] and where the advanced rate from q to q' is dQ(t+R/c)/dt = Q'[1 + (dR/dt)/c], then the resultant time-average root-mean-square action is given by
. Identifying Q' with the Coulomb potential energy qq'/R, the Weber potential is obtained. Using the same argument, Newtonian gravitation yields a corresponding Weber potential energy, qq'/R being replaced by ( - Gmm'/R). 相似文献
19.
The temperature dependences of the quenching rate constants of the states
N 2 (${\rm C} \ {^{3}{
\rm \Pi }_{u}}${\rm C} \ {^{3}{
\rm \Pi }_{u}} v ′=0,1) by N 2 (X) and of the state
N 2 (${\rm C} \ {^{3}{
\rm \Pi }_{u}} \ v^{\prime}=0${\rm C} \ {^{3}{
\rm \Pi }_{u}} \ v^{\prime}=0) by O 2 (X) are studied.
Time-resolved light emission from the gas was analyzed in the temperature
range from 300 K to 210 K keeping the gas at constant density. In case of
quenching by N 2 (X), the quenching rate constant for the vibrational
level v ′= 0 increases by (13 ±3)% with gas cooling whereas the
quenching rate constant for v ′= 1 decreases by (5.0 ±2.5)% in this
temperature range. For quenching by O 2 (X), the quenching rate constant
decreases by (3 ±2)% with gas cooling. The temperature variation of
the N 2 (C 3Π u v ′=0) emission intensity for pure nitrogen
and dry air are calculated using the obtained quenching rate constants and
is compared with the experimental data available in the literature. 相似文献
20.
The aim of this paper is to prove that if V is a strictly convex potential with quadratic behavior at ∞, then the quotient μ 2/μ 1 between the largest eigenvalue and the second eigenvalue of the Kac operator defined on L 2(? m ) by exp ? V(x)/2 · exp Δ x · exp ? V(x)/2 where Δ x is the Laplacian on ? m satisfies the condition: $${{\mu _2 } \mathord{\left/ {\vphantom {{\mu _2 } {\mu _1 {{ \leqslant \exp - \cosh ^{ - 1} (\sigma + 1)} \mathord{\left/ {\vphantom {{ \leqslant \exp - \cosh ^{ - 1} (\sigma + 1)} {2,}}} \right. \kern-\nulldelimiterspace} {2,}}}}} \right. \kern-\nulldelimiterspace} {\mu _1 {{ \leqslant \exp - \cosh ^{ - 1} (\sigma + 1)} \mathord{\left/ {\vphantom {{ \leqslant \exp - \cosh ^{ - 1} (\sigma + 1)} {2,}}} \right. \kern-\nulldelimiterspace} {2,}}}}$$ where σ is such that Hess V(x)≥σ>0. 相似文献
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