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91.
I. Sick 《Progress in Particle and Nuclear Physics》2003,50(2):463-481
We discuss inclusive scattering of electrons from composite systems. In particular, we consider the examples of quasi-elastic electron-nucleus scattering and deep-inelastic electron-nucleon scattering, DIS, processes that have much in common. The study of DIS in a way analogous to past studies of quasi-elastic scattering provides new insight, in particular in what concerns the role of final-state interaction and the importance of binding of the constituents. 相似文献
92.
C. S. Edwards H. S. Margolis G. P. Barwood S. N. Lea P. Gill W. R. C. Rowley 《Applied physics. B, Lasers and optics》2005,80(8):977-983
A pair of 1.5 μm semiconductor laser frequency standards have been developed for optical telecommunications use, stabilised to Doppler-free transitions of the ν1 + ν3 and ν1 + ν2 + ν4 + ν5 combination bands of 13C2H2. The Allan deviation σ/f for a laser locked to line P(10) of the former band follows a slope of 1.6 × 10−12τ−1/2, reaching a minimum of 5.7 × 10−14 at τ = 4000 s. The absolute frequencies of 61 lines of the ν1 + ν3 band and 43 lines of the ν1 + ν2 + ν4 + ν5 band, covering the spectral region 1520 nm to 1552 nm, have been measured by use of a combined frequency chain and femtosecond comb, together with a passive optical frequency comb generator. The mean uncertainties for the line frequencies within each band are 1.4 kHz for the ν1 + ν3 band and 1.9 kHz for the ν1 + ν2 + ν4 + ν5 band, representing improvements on the precision of previously published data by factors of 100 and 104, respectively. Improved values of the rotational constant B″ and centrifugal distortion coefficients D″, H″ and L″ of the vibrational ground state are presented.This article is published with the permission of the Controller of HMSO and the Queen’s Printer of Scotland 相似文献
93.
We introduce a novel concept for optical frequency measurement and division which employs a Kerr-lens, mode-locked laser as
a transfer oscillator whose noise properties do not enter the measurement process. We experimentally demonstrate that this
method opens up the route to phase-link signals with arbitrary frequencies in the optical or microwave range while their frequency
stability is preserved.
Received: 23 July 2001 / Published online: 29 November 2001 相似文献
94.
A general phenomenological reaction-diffusion model for flow-induced phase transitions in complex fluids is presented. The
model consists of an equation of motion for a nonconserved composition variable, coupled to a Newtonian stress relation for
the reactant and product species. Multivalued reaction terms allow for different homogeneous phases to coexist with each other,
resulting in banded composition and shear rate profiles. The one-dimensional equation of motion is evolved from a random initial
state to its final steady state. We find that the system chooses banded states over homogeneous states, depending on the shape
of the stress constitutive curve and the magnitude of the diffusion coefficient. Banding in the flow gradient direction under
shear rate control is observed for shear-thinning transitions, while banding in the vorticity direction under stress control
is observed for shear-thickening transitions.
Received 1 April 2001 and Received in final form 16 June 2001 相似文献
95.
T. Schaub J. Delahaye C. Berger H. Guyot R. Belkhou A. Taleb-Ibrahimi Y. Calvayrac 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,20(2):183-188
High resolution photoemission measurements performed at low temperatures on a single-grained sample of the AlPdMn icosahedral
phase show that the density of states N(E) strongly depends on the nature of the surface. For an ordered quasicrystalline surface, prepared by Ar etching and ultra
high vacuum annealing, a dip feature is observed in N(E) near the Fermi level, which energy dependence can be analyzed with a simple square-root power law. By contrast, N(E) varies only little with energy both for a disordered surface and a crystalline surface of the same sample. A sharp Fermi
edge is then clearly observed. This shows that the metallic character of the surface of a quasicrystal is strongly reduced
when the surface presents a quasicrystalline ordering.
Received 19 February 2000 and Received in final form 6 November 2000 相似文献
96.
Decays of neutral D-mesons are considered phenomenologically without invoking any particular models. Special attention is given to cascade decays
with intermediate neutral kaons where coherent double-flavour oscillations (CDFO) become possible. We show necessity and unique
possibilities of experiments on CDFO. They allow to relate with each other widths and masses of D-meson eigenstates, to separate interference effects due to D
0-ˉD
0 mixing and/or Cabibbo-favoured vs. doubly-suppressed transitions. Such experiments provide the only known ways to unambiguous
model-independent measurements of all CP-violating parameters and of Cabibbo-doubly-suppressed amplitudes, where the New Physics may have more prominent manifestations.
Similar experiments would be useful and interesting also for charged D-meson decays to neutral kaons.
Received: 13 August 1998 相似文献
97.
A. Ghosh S. N. Karmakar 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,8(4):575-582
We present an exact real-space renormalization group (RSRG) scheme for the electronic Green's functions of one-dimensional
tight-binding systems having both nearest-neighbor and next-nearest-neighbor hopping integrals, and determine the electronic
density of states for the quasiperiodic Fibonacci chain. This RSRG method also gives the Lyapunov exponents for the eigenstates.
The Lyapunov exponents and the analysis of the flow pattern of hopping integrals under renormalization provide information
about the nature of the eigenstates. Next we develop a transfer matrix formalism for this generalized tight-binding system, which enables us to determine the wave function amplitudes.
Interestingly, we observe that like the nearest-neighbor tight-binding Fibonacci chain, the present generalized tight-binding
system also have critical eigenstates, Cantor-set energy spectrum and highly fragmented density of states. It indicates that
these exotic physical properties are really the characteristics of the underlying quasiperiodic structure.
Received 5 April 1999 相似文献
98.
Absolute frequency measurement of iodine lines with a femtosecond optical synthesizer 总被引:2,自引:0,他引:2
R. Holzwarth A.Yu. Nevsky M. Zimmermann Th. Udem T.W. Hänsch J. von Zanthier H. Walther J.C. Knight W.J. Wadsworth P.St.J. Russell M.N. Skvortsov S.N. Bagayev 《Applied physics. B, Lasers and optics》2001,73(3):269-271
We have used a single laser femtosecond optical frequency synthesizer together with a widely tunable Nd:YAG laser to measure
the absolute frequency of several absorption lines in molecular iodine around 532 nm. The use of two different repetition
frequencies allows us to determine the number of modes used for the frequency measurement unambiguously. The lines also provide
data for the determination of improved ro-vibrational constants of the iodine molecule.
Received: 3 July 2001 / Published online: 19 September 2001 相似文献
99.
A. Godone F. Levi S. Micalizio J. Vanier 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):5-13
An analysis of the phenomenon of coherent population trapping as observed by means of the dark state in the case of optically
thick vapors in alkali metal atoms is presented. Very different behaviors are predicted for the observation of the dark state
in the fluorescence and transmission spectra of the same atomic sample when the optical length is not negligible. Among other
effects, the dark line observed in the fluorescence signal may look inverted appearing as a bright line, while in the transmission
signal a narrowing of the line width resonance line is observed for an increase of the atomic density. In the pure three-level
scheme a subnatural width is predicted. These effects, related to the electromagnetically induced transparency phenomenon,
are readily observed in experiments, which are found to be in excellent agreement with the theory developed.
Received 28 March 2001 and Received in final form 3 October 2001 相似文献
100.
W. Y. Hwang D. Ahn S. W. Hwang Y. D. Han 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):129-132
We report that entangled pairs of quantum clocks (non-degenerate quantum bits) can be used as a specialized detector for precisely
measuring difference of proper-times that each constituent quantum clock experiences. We describe why the proposed scheme
would be more precise in the measurement of proper-time difference than a scheme of two-separate-quantum-clocks. We consider
possibilities that the proposed scheme can be used in precision test of the relativity theory.
Received 7 November 2001 相似文献