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1.
The energies of the n2P12 (7 ≤ n ≤ 13) and n2P32 (7 ≤ n ≤ 27) levels of CsI have been redetermined photographically from high resolution absorption measurements of the principal series lines 62S12? n2PJX. The new data disagree significantly [ ≈0.13 cm-1] with the values given in the NBS-Tables of Moore1 which are taken from a paper by Kratz.2 By means of an extended Ritz-formula, the ionization energy of CsI was found to be 31406.46±0.03 cm-1, which is, within the limit of uncertainty, in agreement with the data of Kleiman,3 Eriksson et al.,4 Bockasten,5 and Eriksson and Wenåker.6  相似文献   

2.
Usual theories for time-dependent effects in superparamagnetism (over-turning of large spin clusters) assume a flip rate exp (-U/kT). Instead, following Lifshitz and Kagan, we calculate the flip rate due to quantum-mechanical zero-point motion. The resulting “zero temperature” flip rate is R0 exp (-cn) for a cluster with n spins. R0 and c depend on domain wall energy and mass; typically, R0 = 1013n23sec-1 and c = 1.  相似文献   

3.
We study the correlation function 〈σ0x(t)σnx(0)〉 of the transverse Ising model in a critical field whose hamiltonian is 12Σllxσl+1xlz}. At an arbitrary temperature T we relate the autocorrelation to a Fredholm determinant. Moreover at T = 0 the correlations are given by a Painlevé V function for all n. The long-time asymptotic behavior of this function is found and the connection problem is studied. This result contains oscillatory terms which are related to the density of states at the Brillouin zone boundary.  相似文献   

4.
The transverse spin pair correlation function pxn=<SxmSxm+n>=<SxmSxm+n> is calculated exactly in the thermodynamic limit of the system described by the one-dimensional, isotropic, spin-12, XY Hamiltonian
H=?2Jl=1N(SxlSxl+1+SylSyl+1)
. It is found that at absolute zero temperature (T = 0), the correlation function ρxn for n ≥ 0 is given by
ρx2p=142π2pΠj=1p?14j24j2?12p?2jif n=2p
,
ρx2p+1142π2p+1Πj=1p4j24j2?12p+2jif n=2p+1
, where the plus sign applies when J is positive and the minus sign applies when J is negative. From these the asymptotic behavior as n → ∞ of |?xn| at T = 0 is derived to be xn| ~ an with a = 0.147088?. For finite temperatures, ρxn is calculated numerically. By using the results for ?xn, the transverse inverse correlation length and the wavenumber dependent transverse spin pair correlation function are also calculated exactly.  相似文献   

5.
The 169Tm(t, α)168Er reaction has been studied using 17 MeV polarized tritons from the Los Alamos National Laboratory tandem Van de Graaff accelerator. The α-spectra were analyzed with a Q3D magnetic spectrometer. The overall energy resolution was typically ~ 15 keV (FHWM) and angular distributions of cross sections and analyzing powers were obtained for levels up to ~ 2.7 MeV. The fact that spins and parities for all levels up to ? 2 MeV were previously known from an extensive series of (n, γ) studies made it possible to determine specific two-quasiproton structures for many bands from the present results. The Kπ = 2+ γ-vibrational band was found to have a large 32+ [411]p + 12+[411]p admixture, consistent with the predicted microscopic composition of this phonon, but no 52[413]p ? 12+ [411]p component was observed. The Kπ = 04+ band at 1833 keV has ~ 25% of the 12+ [411]p ? 12+[411]p two-quasiproton strength. This is in excellent agreement with the Soloviev model but is inconsistent with the interacting boson model, in which the Kπ = 04+ band is composed almost completely of multiphonon configurations that should not be populated in a single-nucleon transfer reaction. The Kπ = 4?, 72?[523]p + 12+ [411]p two-quasiproton and the Kπ = 4?, 72+[633]n + 12?[521]n two-quasineutron states are mixed strongly with each other, but the two Kπ = 3? bands composed of antiparallel couplings of the same particles are not. A good qualitative explanation of this mixing pattern is provided in terms of the effective neutron-proton interaction.  相似文献   

6.
We consider a neutrino field with geodesic rays in interaction with a gravitational field admitting a Killing vector field nμ. It is found that for solutions of the Einstein-Weyl field equations the neutrino field ξA and the neutrino flux vector lμ are restricted by the equations: LnξA = ?12is ξA and Lnlμ = 0, whereas s is a real constant. In the case of pure radiation neutrino fields these equations become: LξA = case12(p ? is)ξA, Lnlμ = plμ, where p and s are in general real functions of the coordinates.  相似文献   

7.
The level structure of 117Sb was investigated in the reactions 115In(α, 2nγ)117mSb, 117Sn(d, 2nγ)117mSb and 117Sn(p, nγ)117mSb. In order to confirm level sequences and to assign spins and parities to levels populated in the decay of the isomeric three-particle state T12 = 340 μs), prompt and delayed γ-ray spectra, lifetimes, γ-γ coincidences, γ-ray angular distributions, conversion electrons and excitation functions were measured. The spin 252+ of the isomeric state can be explained by the three-particle configuration [π(d52); v(h112)2 10+]252+. This is supported by the experimentally determined g-factor of g = O.115 ± 0.006. Other levels in 117Sb can be interpreted as particle states coupled to anharmonic vibrations of the core. The existence of an excited 92+[404] quasirotational band is experimentally proved and is supported by calculations of the equilibrium deformation.  相似文献   

8.
Revised and more complete vibrational assignments are made for the 3540-Å π1 ← n band system of malonaldehyde. The 0+0? tunneling splitting is found to be 19 ± 11 cm?1 for the 1 state and this represents a 7-cm?1 decrease relative to the ground electronic state. The tunneling splitting and the Franck-Condon envelope of intensities in the 185-cm?1 upper-state progression suggest that the 1B1(nπ1) state is significantly less tightly hydrogen-bonded than the ground 1A1 state.  相似文献   

9.
The odd-mass nucleus 107Cd was investigated in the reactions 105Pd(α, 2n)107Cd, 107Ag(d, 2n)107Cd and107Ag(p, n)107Cd. The constructed level scheme is based on results, obtained from singles γ-ray spectra and excitation functions, from the measurements of delayed γ-rays, of γ-γ coincidences, of internal conversion electrons and of γ-ray angular distributions. Two new isomers were observed. The first one, interpreted as the h112 neutron state at 845.6 keV has a half-life of 67 ± 6 ns. This isomeric state is populated by a strong E2 cascade. Bands built on the other intrinsic states with spins and parities 52+ and 72+ are not strongly populated. For the second isomeric state at an excitation energy of 2679 keV a half-life of 55±4 ns was determined. This isomer is probably a three-quasiparticle state. Its configuration can be proposed as [π(g92)?28+ν(72)1]212+.  相似文献   

10.
The mobility μ of a very pure semiconductor at very low temperatures is investigated in terms of a model where electrons are scattered by charged impurities distributed uniformly in space, and the electron-electron interaction is taken into account by the Debye-Hueckel screening in the interaction potential. The equation for the current relaxation rate Γ, derived previously by the proper connected diagram expansion, incorporates the quasi-particle effect in a self-consistent manner. The solution of this equation at high carrier concentrations n yields the so-called Brooks-Herring formula. At lower concentrations, the solution deviates significantly from the latter. The solution is in general smaller than the standard expression for the rate based on the Boltzmann equation; and this is consistent with the existing conductivity data available. At the very low concentrations e.g. n = n3 = 1013cm?3 or lower for Ge, the mobility calculated is inversely proportional to the square-root of the impurity concentration ns, and has a T14-dependence (T: temperature).
μ = 0.3597&z.xl;h12k(kBT) 14(ze)?1ns?12m1?34
, where k is the dielectric constant. The conductivity data directly comparable with this formula are not available at present. However, the quasi-particle effect which led to this peculiar concentration-dependence should also show itself in the cyclotron resonance width; there, experiment and theory both show the ns-dependence for very pure semiconductors.  相似文献   

11.
12.
Levels of 48Sc up to 3.33 MeV excitation were studied by the reaction 48Ca(p,nγ)48Sc employing a variety of experimental techniques. A level scheme of 48Sc comprising 29 excited states and 54 transitions were determined from the measurements of γ-γ coincidences and γ-ray excitation functions. Within the framework of the statistical compound nucleus model spins and parities of the 48Sc levels were assigned from the angular distributions and linear polarizations of the de-excitation γ-rays as well as the excitation functions of the residual levels. From the present experimental results and other available data we tentatively identified some of the levels of the (1f729, 1d32?1), (1f729, 2s12?1), (1f727, 2p32) and (1f727, 1f52) configurations in addition to the well-known (πf72, vf72?1) multiplet.  相似文献   

13.
14.
It is proved that the trace of the generalized Trotter formula Z(n) ≡ Tr[II exp(Ajn]n is an even function of n, when all Aj are symmetric, namely Atj = Aj, togethern with some generalizations. This yields a new extrapolatio n method of the form Z(n) ? Z(∞) + a/(n2 + b) for large n in quanntum Monte Carlo simulations.  相似文献   

15.
Vertex constants for virtual decays t→d+n and t→d1+n are calculated using the resonance expansion technique for the three-particle amplitude suggested recently in ref. [1]. In the model with a spin-dependent separable NN-potential values Gtdn2=1.92 fm, Gtd1n2=?0.38 fm are obtained.  相似文献   

16.
17.
Electrical resistivity, mobility, magnetoresistance in compensated n type InP with a carrier density n = 7,2 1016/cm3 have been measured in the temperature range 1,7 K – 100 K, in magnetic fields up to 0,9 Tesla. Under a temperature TC, which corresponds to the formation of an impurity band in which the electron conduction is metallic, the magnetoresistance becomes negative. Longitudinal and transverse magnetoresistances have similar behaviours. Longitudinal magnetoresistance which is treated here, has the behaviour of a system of paramagnetic spins for which the Curie point is determined. The variation of the negative magnetoresistance versus magnetic field and temperature is quite well approximated by a Langevin function L(u) with u = μ1BkT; μ1 = n μB is the effective magnetic moment where μB is the Bohr magneton and n = 5. The value of the effective magnetic moment and the average separation of donors, allow the discussion of the negative magnetoresistance on the basis of the Toyozawa model. Other models are discussed and it seems that in the range of impurity concentrations concerned, the picture of localised moments is more consistant that a “mobility edge” model.  相似文献   

18.
Neutron reduced widths Γn0 and Γn1 are reported for about 200 resonances observed in neutron total cross sections of Ca40, 44, Ti48, Cr50, 52, 54, Fe54, 56, Ni58, 60, Sr88, Y89, Sn124, Te130, Ba136, 138, and Pb206, 207, 208, in the energy region 1 to 200 kev. Average parameters Γn0, Γn0D, and Γn(1)D have been derived and the Wigner distribution for local spacings and the Porter-Thomas distribution for reduced widths are verified for the resonances in the even-even nuclei Ca40, Fe56, Ni58, and Ni60. A simple method of area analysis which is less tedious and time consuming than the method reported before in Part III is also described.  相似文献   

19.
The small ω′ behaviour of F2en/F2ep and the apparent difference in the q2 dependences of the magnetic form factor of the proton and of the transition to Δ+(1236) are quantitatively correlated in a model where nucleon consistes of a quarks and a scalar or vector core. The proton and Δ transition form factors suggest that only the scalar core contributes at large q2 and small ω′. As a result the ω′ dependence of F2enF2ep is obtained for ω′ < 3 and predictions for the weak structure functions and polarisation asymmetries at smallω′ are presented. We predict FνpFνnω′→10 asymmetries ω′→11 and also expect that GmnGmp?12 as q2→∞.  相似文献   

20.
The masses of composite leptons and quarks are discussed in a “dynamical subquark model of pregauge interactions”. In this model, the leptons and quarks are made of a spinor and scalar subquark with equal mass, M, and the gauge bosons and Higgs scalar of the SU(3)c×SU(2)L×U(1)Y model are made of a subquark-antisubquark pair. The SU(2)L×U(1)Y symmetry is spontaneously broken by the composite Higgs scalar and the (scalar) subquark mass parameter is in turn bounded as M > 5.4 TeV (=2π(2GF?1)12where GF is the Fermi coupling constant). The spontaneously generated mass of a lepton or quark, mi(n) (i = 1, 2; n = 1 ~ Ng), is calculated to be: mi(n) = ri(n) = ri(n) × (4+3Nge.m.(2GF?1)12/36 (=0.35ri(n) (4+3Ng)GeV), where ri(n) are the parameters satisfying that 0 ? ri(n) ? 1 and Σ (ri(n))2 = 1;Ng is the total number of generations of the leptons and quarks; αe.m. is the fine structure constant. The appearance of light composite fermions is related to a specific mechanism of generating global chiral symmetries of the leptons and quarks. Global symmetries of scalar subquarks yield chiral symmetries of the leptons and quarks. Our model turns out to satisfy 't Hooft's anomaly conditions on massless composite fermions.  相似文献   

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