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Over the years, a number of investigators have tried to solve the problems in the direct measurement of moment mobility. However, no one has found a moment excitation system that can produce a pure and sufficiently powerful moment. In the past, most investigators tried to solve the problem of impurity in moment by tackling the problem in unmatched shakers in a moment exciter. Su and Gibbs (Su J, Gibbs BM. Measurement of point moment mobility in the presence of non-zero cross mobility. Applied Acoustics 1998;54(1):9-26) have indicated theoretically that compromise between the purity and the power of a moment generated by the moment exciter is greatly affected by the output force impedance of the moment excitation system. In this paper, experiments have been conducted to investigate the effect of output force impedance on direct measurement of moment mobility from which theory of Su and Gibbs has been verified. Methods of improvements of the moment exciter have been proposed in order that the moment exciter can generate a pure and sufficiently powerful moment.  相似文献   

3.
Mineev  V. P. 《JETP Letters》2010,90(12):768-770
JETP Letters - The roton excitation in the superfluid 4He does not possess a stationary dipole moment. However, a roton has an instantaneous dipole moment, such that at any given moment one can...  相似文献   

4.
V. P. Mineev 《JETP Letters》2009,90(12):768-770
The roton excitation in the superfluid 4He does not possess a stationary dipole moment. However, a roton has an instantaneous dipole moment, such that at any given moment one can find it in the state either with positive or with negative dipole moment projection on its momentum direction. The instantaneous value of electric dipole moment of roton excitation is evaluated. The result is in reasonable agreement with recent experimental observation of the splitting of microwave resonance absorption line at roton frequency under external electric field.  相似文献   

5.
We demonstrate via first-principle calculations based on the density functional theory that the magnetic moment of a helium atom under a given magnetic field has a positive correlation with the electric dipole moment when an external electric field is applied to the system. Our calculation shows that the enhancement of the magnetic moment is significant due to the reduction of the tripletsinglet splitting. We argue that this finding can be generalized to organic molecules, especially to macromol...  相似文献   

6.
We calculated the contribution of internal nucleon electric dipole moments to the Schiff moment of (199) Hg. The contribution of the proton electric dipole moment was obtained via core polarization effects that were treated in the framework of random phase approximation with effective residual forces. We derived a new upper bound |d(p)|<5.4 x 10(-24)e cm of the proton electric dipole moment.  相似文献   

7.
The Schiff moment of the 199Hg nucleus is calculated using finite range P-and T-violating weak nucleon-nucleon interaction. Both the contributions of the P-and T-odd interaction and of internal nucleon electric dipole moments to the Schiff moment of 199Hg are calculated. The contribution of the proton electric dipole moment is obtained via core-polarization effects treated in the framework of RPA with effective residual interactions. We derive a new upper bound |d p |<5.4×10?24e cm for the proton electric dipole moment.  相似文献   

8.
周国全 《大学物理》2007,26(4):7-11
基于旋转带电体的磁矩与刚体转动惯量之间的类比关系,引入带电体的一个不同于电四极矩的电矩张量的概念,进而引入标量电矩二次曲面及电矩主轴的概念,借助正交变换及电矩张量矩阵的本征值理论,推导出沿任意方向定轴旋转带电体的磁矩的计算公式及电矩张量的若干性质,并举例说明.  相似文献   

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电子的电矩     
依据狄拉克方程的相关结论指出,电子除磁矩外还存在体现在高阶效应中的电矩.  相似文献   

12.
The ground state nuclear moments of186Ir (j π=5(+)) have been determined with NMR on oriented186Ir in Ni as |μ|=3.80 ?0.02 +0.12 μ n andQ=?3.00 (15)b. The quadrupole moment is consistent with an anamolousj π K=5+0 or 5+1 ground state configuration. The explanation of the magnetic moment in terms of pure 5+0 or 5+1 configurations would require a high collectiveg R-factor ofg R≧0.76. On the other hand the magnetic moment can be explained with a “normal”g R and a mixed ground state configuration.  相似文献   

13.
The magnetic structure factors of MnAlGe (space groupP4/nmm) measured with polarised neutrons have been expressed in terms of the magnetic moment of the Mn atom (site symmetry tetrahedral with tetragonal distortion), the Bessel transforms 〈j n〉 of the Mn radial functions and the fractional occupancies of the moment density in the various crystal field orbitals. The measured structure factors were least-squares fitted with the theoretical expression involving 〈j n〉 appropriate to the Mn0, Mn+ and Mn2+ atoms. The best fit was got using Mn0 transforms, yielding 1·45µ B as the Mn magnetic moment. The fractional occupancies of the moment density in the crystal field orbitalsA 1g,B 1g E g andB 2g were obtained. This analysis shows the magnetic moment to be highly non-spherical with a large fractional occupancy (38%) in theA 1g orbital directed along the tetragonal axis while the fractional occupancies ofB 1g andB 2g are found to be 31% and 30% respectively. The fractional occupancy of the moment in theE g orbital directed towards the Ge and Al atoms is very low (1%). The spatially averaged moment density of Mn in MnAlGe is more diffuse than that of Mn I and Mn II in isostructural Mn2Sb.  相似文献   

14.
This paper develops a modified moment method for the numerical solution of two “Pocklington Type” integral equations. The first equation arises from the problem of scalar diffraction through a slot; the second from scattering by a straight, thin-wire. Numerical results and comparison with a more conventional method are given.  相似文献   

15.
Interaction of charged leptons with photons is considered for the case when one of the lepton legs is off the mass shell. The effect due to off-mass-shell shift in the anomalous magnetic moment is computed within one-loop approximation. Possible contributions of this effect in the muon g — 2 measurements are discussed.  相似文献   

16.
An extra neutron added to a doubly magic nuclear core should give a nuclear magnetic moment, μ, in close agreement with the Schmidt value. However, the magnetic moment of 57Ni, measured through nuclear alignment at 3–20 mK, is equal to ∣μ∣ = 0.88±0.06 μN which is only 45% of the Schmidt value. Comparison with several nuclear structure calculations is made.  相似文献   

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The magnetic response of a two-dimensional layer rolled into a cylinder and located in a longitudinal magnetic field is examined. The magnetic moment of the degenerate electron gas is studied as a function of the magnetic flux. The shape of the fluctuation maxima is analyzed in detail. It is shown that at zero temperature there are breaks in each period of the change in the magnetic moment. Over this period, a plot of the magnetic moment depends strongly on the ratio of the Fermi energy to the size-confinement energy. In particular, there are no breaks for integral or semi-integral values of the square root of this ratio. Fiz. Tverd. Tela (St. Petersburg) 41, 856–858 (May 1999)  相似文献   

19.
The magnetic moment of the23Mg (I =3/2+, T1/2=11.3 s), has been determined as |(23Mg)|=0.5364±0.003 µN by use of -NMR detection with the recoil polarization obtained through a low energy nuclear reaction.  相似文献   

20.
magnetovolume variations deduced from the thermal expansion data of Roberts, White and Fawcett on Cr and a CrV alloy show the decay of ground state magnetic order in Cr (including short range order above the Néel temperature TN); this decay appears to be partially counteracted by the growth of paramagnetic spin fluctuations in qualitative agreement with spin fluctuation theories of magnetism. The inferred ground-state magnetovolume in Cr is about 0.22%.  相似文献   

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