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1.
The preliminary results on the tensor T20 analyzing power for the 12C(,p)13C* reaction with the excitation of 13C levels and the d(,p)X reaction at the energies T d = 140, 200 and 270 MeV at the emission angle Θ cm = 0° are presented. The data on the tensor A yy and vector A y analyzing powers for the 12C(,p)13C* reaction at the energy T d = 270 MeV in the angular range from 4° to 18° in the laboratory are also obtained.  相似文献   

2.
Consider the electrical resistancer n (p) of a hypercubic bond lattice [O,n] d inZ d , where the bonds have resistance 1 with probabilityp or with probability 1-p. Letp n (p)=n 2-d r n (p) andp(p)=limnpn(p). It is well known thatp(p)< ifp>p c andp(p)= ifp<p c , wherep c is the percolation threshold. Here we show thatp(p c )=, and .  相似文献   

3.
The investigation of the spin structure of d, 3H, and 3He has been performed at the RIKEN acceleration research facility and VBLHE. Vector A y and tensor A yy , A xx , A xz analyzing powers for d3Hen and d3Hp are presented at 270 MeV. Themirror channels (3Hen and 3Hp) are comparedto each other in order to find possible manifestation of charge-symmetry breaking. The preliminary results on the polarization observables for d3Hp at 200MeV are also presented. The obtained data are compared with one-nucleon-exchange calculations.As a byproduct, dpX and 12C → pX breakup reactions are investigated at 140, 200, and 270MeV. The experimental data on p elastic scattering were obtained at 270, 880, and 2000 MeV at the Nuclotron. The polarization of the deuteron beam was measured at 270 MeV at the internal target station. The preliminary data on the vector A y and tensor A yy , A xx analyzing powers for the p elastic scattering at 880 MeV are presented. The calculations on A y , A yy , and A xx analyzing powers for the p elastic scattering at 880 MeV were performed in the framework of the multiple-scattering model. The text was submitted by the authors in English.  相似文献   

4.
The stiffness exponents in the glass phase for lattice spin glasses in dimensions are determined. To this end, we consider bond-diluted lattices near the T = 0 glass transition point p*. This transition for discrete bond distributions occurs just above the bond percolation point pc in each dimension. Numerics suggests that both points, pc and p*, seem to share the same 1/d-expansion, at least for several leading orders, each starting with 1/(2d). Hence, these lattice graphs have average connectivities of near p* and exact graph-reduction methods become very effective in eliminating recursively all spins of connectivity , allowing the treatment of lattices of lengths up to L = 30 and with up to 105-106 spins. Using finite-size scaling, data for the defect energy width over a range of p > p* in each dimension can be combined to reach scaling regimes of about one decade in the scaling variable . Accordingly, unprecedented accuracy is obtained for the stiffness exponents compared to undiluted lattices (p = 1), where scaling is far more limited. Surprisingly, scaling corrections typically are more benign for diluted lattices. We find in for the stiffness exponents y3 = 0.24(1), y4 = 0.61(2), y5 = 0.88(5), and y6 = 1.1(1).Received: 29 October 2003, Published online: 20 April 2004PACS: 05.50. + q Lattice theory and statistics (Ising, Potts, etc.) - 64.60.Cn Order-disorder transformations; statistical mechanics of model systems - 75.10.Nr Spin-glass and other random models - 02.60.Pn Numerical optimization  相似文献   

5.
Heterogeneous kinetics are shown to differ drastically from homogeneous kinetics. For the elementary reaction A + A products we show that the diffusion-limited reaction rate is proportional tot h[A]2 or to [A]x, whereh=1- d s/2, X=1+2/d s =(h-2)(h-1), andd s is the effective spectral dimension. We note that ford = d s =1, h =1/2 andX = 3, for percolating clustersd s = 4/3,h = 1/3 andX = 5/2, while for dust ds <1, 1 >h > 1/2 and >X > 3. Scaling arguments, supercomputer simulations and experiments give a consistent picture. The interplay of energetic and geometric heterogeneity results in fractal-like kinetics and is relevant to excitation fusion experiments in porous membranes, films, and polymeric glasses. However, in isotopic mixed crystals, the geometric fractal nature (percolation clusters) dominates.  相似文献   

6.
We report the general trend of the nonrelativistic Hartree-Fock relativistic Hartree-Fock, nonrelativistic configuration-interaction, and relativistic configuration-interaction length form of the oscillator strengths for the resonance excitation 1s 22s 22p63s 2 S J e 1s 22s 22p 53s 2 2 P J o . transition, which leads to autoionization (Auger transition), in Na, Mg1+, Al2+, Si3+, P4+, S5+, Cl6+, Ar7+, K8+, Ca9+, Sc10+, Ti11+, Fe15+, Cu18+, Zn19+, Br24+, and Kr25+ ions of the sodium isoelectronic sequence.  相似文献   

7.
Sulfur atoms are produced in the excited 3s 23p 4 1 D 2 and 3s 23p 4 1 S 0 levels by two-photon photodissociation of CS2 in the gas phase in the region 285–305 nm. These excited atoms are detected by three-photon (two to resonance) ionisation at selected laser wavelengths. Many new transitions have been observed which have not been reported previously. The new dark states that have been accessed by two-photon absorption have been characterised and the energy levels with respect to the ground 3 P 2 state have been determined. Configuration interaction between 6p 3 P 1, 6p 5 P 1, and 4p1 P 1 states, and also between 6p 3 P 2, 6p 5 P 2, and 4p1 D 2 states has been observed. It is found that intermediate states reached from the 1 S 0 level through two-photon absorption lie above the first ionisation potential of S+(4 S 0). It is proposed that autoionisation into the 4 S 0+e continuum is a dominant mechanism in the decay of these levels, although ionisation by a further photon absorption is not ruled out.  相似文献   

8.
Integral yields of spontaneous emission at wavelengths of 1.73, 2.03, and 2.65 μm have been measured upon excitation of pure xenon by a pulsed electron beam. These yields have been analyzed and experimental data have been obtained on time constants of radiative transitions 5d[3/2]1 → 6p[5/2]2, 5d[3/2]1 → 6p[3/2]1, and 5d[3/2]1 → 6p[1/2]0 of XeI, which appeared to be equal to (2300 ± 400) × 10?9, (300 ± 40) × 10?9, and (1300 ± 200) × 10?9 s, respectively. It is shown that the experimental data are in a qualitative agreement with the results of computational and theoretical investigations. The results of averaging the experimental and calculated data are proposed for use as recommended values of the corresponding constants.  相似文献   

9.
From temperature-dependent X-ray photoemission (XPS) spectra between 300 and 10 K of Sr doped La2CuO4 and 123 compounds (YBa2Cu3O7–) we deduce the absence of the Cu3d 8(Cu3+) configuration in the ground state of these Mott insulators. The metallic character of these samples and involving those Cu atoms which are relevant for the superconducting properties arises from (d 9 p 6)+(d 10 p 5) valence fluctuations, while the superconducting transition is indicated to be closely related to an incipient oxygen dimerization which is best detected upon cooling far belowT c .  相似文献   

10.
Thed-dimensional random Cantor set is a generalization of the classical middle-thirds Cantor set. Starting with the unit cube [0, 1] d , at every stage of the construction we divide each cube remaining intoM d equal subcubes, and select each of these at random with probabilityp. The resulting limit set is a random fractal, which may be crossed by paths or (d–1)-dimensional sheets. We examine the critical probabilityp s(M, d) marking the existence of these sheet crossings, and show that ps(M,d)1–pc(M d) asM, where pc(M d) is the critical probability of site percolation on the lattice (M d) obtained by adding the diagonal edges to the hypercubic lattice d. This result is then used to show that, at least for sufficiently large values ofM, the phases corresponding to the existence of path and sheet crossings are distinct.  相似文献   

11.
This work is devoted to the determination of the vibrational population of hydrogen molecules in the ground and excited electronic states from the analysis of visible spectra of the H2 molecules excited by an RF discharge in an expanding thermal arc plasma. Comparison of the experimental results on relative electron-impact excitation cross sections for the transition H2(X1Σ, υ0 = 0)→ H2(d3IIu, υ′) with other experiments, and with calculations based on the Franck-Condon principle, shows good agreement. This means, that for plasma under investigation: 1) in the ground electronic state H2(d3IIu,υ′), only the lowest vibrational level with υ0 = 0 is significantly populated, and 2) direct electron exictation of H2(d3IIu, υ′, υ′) state from the ground state H2(X1Σ, υ0 = 0) dominates.  相似文献   

12.
The optical constants (the refractive index n, the absorption index k, and the absorption coefficient ) of CdIn2Se4 thin films were determined in the spectral range of 500–2000 nm. Graphical representation of log() as a function of log(1/) shows two distinct, linear parts indicating the existance of both direct and indirect optical transitions. The corresponding forbidden energy gaps E g d and E g Emphasis>d were determined. The effect of both annealing temperature as well as the substrate temperature on the optical constants of CdIn2Se4 thin films was also investigated.  相似文献   

13.
Computer simulations on binary reactions of random walkers (A + A A) on fractal spaces bear out a recent conjecture: ( –10 –1) t f , where is the instantaneous walker density and 0 the initial one, andf=d s /2, whered s is the spectral dimension. For the Sierpinski gaskets:d=2, 2f=1.38 (d s =1.365);d=3, 2f=1.56 (d s =1.547); biased initial random distributions are compared to unbiased ones. For site percolation:d= 2,p=0.60, 2f= 1.35 (d s =1.35); d=3,p=0.32, 2f=1.37 (d s =1.4); fractal-to-Euclidean crossovers are also observed. For energetically disordered lattices, the effective 2f (from reacting walkers) andd s (from single walkers) are in good agreement, in both two and three dimensions.Supported by NSF Grant No. DMR 8303919.  相似文献   

14.
Cu 3d and O 2p electronic states of Cu2O, CuO, and the highT c compound YBa2Cu3O7– have been probed by means of high resolution x-ray emission spectroscopy (XES). The CuL and OK XES bands are compared in detail with recently reported x-ray photoelectron and ultraviolet photoelectron spectroscopy (XPS and UPS) measurements and densities of states obtained by local density functional (LDF) theory. The XES data show that the hybridization between Cu 3d and O 2p states is completely modified in CuO and YBa2Cu3O7–, whered-d correlation energy is large, as compared to LDF predictions. Such is not the case for Cu2O where agreement between theory and experiment is good.The Cu 3d states are found to be highly localized in YBa2Cu3O7– (though less so than in CuO). The O 2p states lie at lower binding energies than in the simpler oxides and are mainly situated above the Cu 3d states. The respective positions of the centre of gravity of the OK emission bands on an x-ray energy scale indicate that the oxygen sites are less well screened by the O 2p states in the highT c compound. This provides indirect evidence for the presence ofd-like states at the oxygen sites.  相似文献   

15.
Ar+-laser (=488 nm) irradiation of calcium gallate (CG) glass with the composition of 60CaO·39Ga2O3·Fe2O3 resulted in a distinct decrease in the IR transmittance (T) due to the formation of crystalline CaGa2O4 and CaGa4O9 phases. The Mössbauer spectrum of non-irradiated glass comprised a broad doublet due to distorted Fe3+(Td) with, , and of 0.20, 1.33, and 1.00 mm s–1, respectively. An additional doublet due to Fe3+(Td) was observed in the Ar+-irradiated glass and, , and were 0.17, 1.32, and 0.75 mm s–1, respectively. A decrease inT was also observed after the60Co -ray irradiation with doses 105Gy, and the precipitation of CaO, Ga2O3, and CaGa4O7 phases was confirmed by X-ray diffraction.  相似文献   

16.
The method of extrapolation of the parameter of a model potential for states of one electron (4f, 5s, 5p, 5d, 5f) above the core 1s 22s 22p 63s 23p 63d 104s 24p 64d 10 and one vacancy (4d 9) in the same core is applied to calculate the energy levels in the silver and rhodium isoelectronic sequences with the maximum nuclear charge Z = 86. The energy levels of Ag-and Rh-like ions were used for the calculation of the energies of resonance transitions to the ground state 1 S 0 in Pd-like ions. Good agreement between the theoretical and calculated energies of the resonance transitions in Pd-like ions indicates the reliability of the results obtained.  相似文献   

17.
Chlorinated hydrocarbons (CHC), photodissociated at 193 nm, are detected with high sensitivity by observing the atomic chlorine fragment via laser-induced fluorescence (LIF). Photofragment emission spectra from CH3Cl, CH2Cl2, CHCl3, CCl4, C2HCl3, and C2Cl4 demonstrate that photofragment fluorescence and chemiluminescence are negligible in the region 700–800 nm where the 3p 44p 4 S 0 3p 44s 4 P fluorescence from atomic chlorine is detected. There is also negligible interference for photodissociation in Ar, N2, and air bath gases. Total CHC can be readily detected in air flows at mixing fractions less than 20 ppb and averaging times less than 1 minute. Techniques for considerable improvement in this detection limit are discussed.Supported by the NSF  相似文献   

18.
A rotationally constrained forest fire model is studied on square and triangular lattices of size 400×400. The critical probabilityp c for onset of fire propagation is determined. The scaling relationsMt d r, Rgtv andMR g d f are analysed at fire propagation probabilityp=p c whereM is the number of burnt trees,R g the radius of gyration andd f the fractal dimension of the cluster of burnt trees at timet. Numerical estimates ofd t, v andd f have been obtained.  相似文献   

19.
The validity of the finite-size scaling prediction about the existence of logarithmic corrections in the helicity modulus of three-dimensional O(n)-symmetric order parameter systems in confined geometries is studied for the three-dimensional mean spherical model of geometryL 3/s-d×d, 0d<3. For a fully finite geometry the general case ofd p0 periodic,d a0 antiperiodic,d 00 free, andd 10 fixed (d p+da+d0+d1=d, d=3) boundary conditions is considered, whereas for film (d=2) and cylinder (d=1) geometries only the case of antiperiodic and/or periodic boundary conditions is investigated. The corresponding expressions for the finite-size scaling function of the helicity modulus and its asymptotics in the vicinity, below, and above the bulk critical temperatureT c and the shifted critical temperatureT c,L are derived. The obtained results are not in agreement with the hypothesis of the existence of a log(L) correction term to the finite-size behavior of the helicity modulus in the finite-size critical region if d=3. In the case of film and cylinder geometries there are no logarithmic corrections. In the case of a fully finite geometry a universal logarithmic correction term –[(d 0d 1)/4–2da–1/2] lnL/L is obtained only for (T c-T) LlnL.  相似文献   

20.
The probabilities of the 3p 53d, 3p 54s?3p 6, 3p 54p, 3s3p 63d electric dipole transitions and radiative lifetimes of the 3p 53d, 3p 54p, 3p 54s, and 3s3p 63d levels are calculated for the Sc IV–Fe IX isoelectronic sequence.  相似文献   

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