共查询到20条相似文献,搜索用时 46 毫秒
1.
S. Mailis P.T. Brown C.L. Sones I. Zergioti R.W. Eason 《Applied Physics A: Materials Science & Processing》2002,74(2):135-137
Modification of the chemical etching behaviour of undoped congruent z-cut lithium niobate single crystals is achieved by pre-illumination
of the –z face of the crystal with sub-ps ultraviolet laser radiation at 248 nm, at energy fluences below the threshold for
ablation. A systematic study of the effect of the energy fluence and total exposure on the etch frustration is presented.
Received: 23 July 2001 / Accepted: 28 September 2001 / Published online: 20 December 2001 相似文献
2.
I.P. Lokhtin A.M. Snigirev 《The European Physical Journal C - Particles and Fields》2001,21(1):155-162
The potential of coming experiments on the Large Hadron Collider (LHC) to observe the rescattering and energy loss of heavy
quarks in the dense matter created in heavy ion collisions is discussed. We analyze the sensitivity of high-mass pairs from semileptonic decays and secondary 's from single B decays to the medium-induced bottom quark energy loss.
Received: 18 December 2000 / Revised version: 17 May 2001 / Published online: 6 July 2001 相似文献
3.
P. Amaral et al. 《The European Physical Journal C - Particles and Fields》2001,20(3):487-495
The energy loss spectrum of 180 GeV muons has been measured with the 5.6 m long finely segmented Module 0 of the ATLAS hadron
Tile Calorimeter at the CERN SPS. The differential probability per radiation length of a fractional energy loss has been measured in the range ; it is compared with theoretical predictions for energy losses due to bremsstrahlung, production of electron–positron pairs,
and energetic knock-on electrons. The iron elastic form factor correction to muon bremsstrahlung in the region of no screening of the nucleus by atomic electrons has been measured for the first time,
and is compared with different theoretical predictions.
Received: 28 December 2000 / Revised version: 14 February 2001 / Published online: 28 May 2001 相似文献
4.
I.V. Krouglov M. Avrigeanu W. von Oertzen 《The European Physical Journal A - Hadrons and Nuclei》2001,12(4):399-404
Using the framework of the coupled reaction channels (CRC) the elastic scattering and the elastic transfer in the system 6He + 4He measured at E = 151 MeV have been analysed. It is shown that the structure observed in the backward range of the angular distributions
is influenced by the interference of the elastic 2n-transfer with a two-step process passing through the 2+ excitation in 6He. The two-neutron transfer mechanism is studied in the microscopic approach and it is found that for the ground-state transition
the one step dominates by a factor 10 over the two-step mechanism at this energy.
Received: 29 October 2001 / Accepted: 4 December 2001 相似文献
5.
V.A. Petrov A.V. Prokudin 《The European Physical Journal C - Particles and Fields》2002,23(1):135-143
A model of a three pomeron contribution to high energy elastic pp and scattering is proposed. The data are well described for all momenta ( GeV) and energies ( GeV) (). The model predicts the appearance of two dips in the differential cross-section which will be measured at LHC. The parameters
of the pomeron trajectories are
.
Received: 11 July 2001 / Published online: 20 December 2001 相似文献
6.
M. Kuperman D. Zanette 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):387-391
We analyze the phenomenon of stochastic resonance in an Ising-like system on a small-world network. The system, which is subject
to the combined action of noise and an external modulation, can be interpreted as a stylized model of opinion formation by
imitation under the effects of a “fashion wave”. Both the amplitude threshold for the detection of the external modulation
and the width of the stochastic-resonance peak show considerable variation as the randomness of the underlying small-world
network is changed.
Received 19 December 2001 相似文献
7.
Yu Li R.W. Peng G.J. Jin Mu Wang X.Q. Huang A. Hu S.S. Jiang 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(4):497-503
In the tight-binding approximation, we have investigated the behaviour of persistent currents in a one-dimensional Thue-Morse
mesoscopic ring threaded by a magnetic flux. By applying a transfer-matrix technique, the energy spectra and the persistent
currents in the system have been numerically calculated. It is shown that the flux-dependent eigenenergies form “band” structures
and the energy gaps will enlarge if the site energy increases. Actually, the site energy and the filling-up number of electrons
are two important factors which have much influence upon the persistent current. Increment of the site energy in the system
will lead to a dramatic suppression of the currents. When the highest-occupied energy level is on the top of the band, the
total current is limited; otherwise, the persistent current increases by several orders of magnitude. Generally, this kind
of large scale change in the magnitude of the current can easily be observed in the vicinity of band gaps. The parity effect
in the Thue-Morse ring is also discussed.
Received 22 January 2001 and Received in final form 25 October 2001 相似文献
8.
I. Krichever 《Communications in Mathematical Physics》2002,229(2):229-269
The Hamiltonian theory of zero-curvature equations with spectral parameter on an arbitrary compact Riemann surface is constructed.
It is shown that the equations can be seen as commuting flows of an infinite-dimensional field generalization of the Hitchin
system. The field analog of the elliptic Calogero-Moser system is proposed. An explicit parameterization of Hitchin system
based on the Tyurin parameters for stable holomorphic vector bundles on algebraic curves is obtained.
Received: 25 September 2001 / Accepted: 22 December 2001 相似文献
9.
We describe a laser system that readily provides radiation tunable from 2 μm in the infra-red to 35 nm in the extreme ultraviolet
spectral range. The broad spectral range is covered through a range of non-linear processes such as Raman shifting and high-order
harmonic generation. Pulses with duration of tens of picoseconds are obtained. The relative bandwidth of the radiation is
δλ/λ=10-4, comparable with what can be achieved by using high-resolution monochromators at state-of-the-art synchrotron beamlines.
We discuss different methods for characterising the radiation in this wide wavelength regime. We also discuss the capabilities
of the system from the measured parameters.
Received: 12 December 2000 / Revised version: 8 March 2001 / Published online: 27 April 2001 相似文献
10.
M. Mirea O. Bajeat F. Clapier F. Ibrahim A.C. Mueller N. Pauwels J. Proust 《The European Physical Journal A - Hadrons and Nuclei》2001,11(1):59-78
The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron-rich nuclei
based on the neutron-induced fission can be realised using these beams. A theoretical optimization of such a facility as a
function of the incident deuteron energy is reported. The model used to determine the fission products takes into account
the excitation energy of the target nucleus and the evaporation of prompt neutrons. Results are presented in connection with
a converter-target specific geometry.
Received: 1 December 2000 / Accepted: 12 May 2001 相似文献
11.
A. Nehme 《The European Physical Journal C - Particles and Fields》2002,23(4):707-718
We use chiral perturbation theory to evaluate the scattering amplitude for the process at leading and next-to-leading orders in the chiral counting and in the presence of isospin breaking effects. We also discuss
the influence of the latter on the combination of the -wave scattering lengths which is relevant for the 2S–2P energy level shift of atoms.
Received: 19 November 2001 / Revised version: 21 December 2001 / Published online: 5 April 2002 相似文献
12.
E. Ozturk Y. Ergun H. Sari I. Sokmen 《Applied Physics A: Materials Science & Processing》2001,73(6):749-754
In this study, we report results of a self-consistent calculation obtained for the sub-band structure of Si δ-doped GaAs material
by using a new alternative method. We will discuss the influence of the δ-doping concentration and the δ-layerthickness on
the sub-band structure for a non-uniform distribution, which is taken as different from the known Gaussian distribution. The
confining potential, the sub-band energies, the sub-band occupations, and the Fermi energy have been calculated by solving
the Schr?dinger and Poisson equations by using the Airy functions self-consistently.
Received: 4 December 2000 / Accepted: 31 January 2001 / Published online: 26 April 2001 相似文献
13.
A. Guarino S. Ciliberto A. Garcimartın M. Zei R. Scorretti 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(2):141-151
The acoustic emission of fracture precursors, and the failure time of samples of heterogeneous materials (wood, fiberglass)
are studied as a function of the load features and geometry. It is shown that in these materials the failure time is predicted
with a good accuracy by a model of microcrack nucleation proposed by Pomeau. We find that the time interval δt between events (precursors) and the energy ɛ are power law distributed and that the exponents of these power laws depend
on the load history and on the material. In contrast, the cumulated acoustic energy E presents a critical divergency near the breaking time τ which is E∼
. The positive exponent γ is independent, within error bars, on all the experimental parameters.
Received 31 July 2001 and Received in final form 17 December 2001 相似文献
14.
Deep-inelastic scattering at low x and elastic vector meson electroproduction are analyzed on the basis of the s-channel unitarity extended to off-shell particle scattering. It appeared that the role of unitarity is important, but contrary
to the case of on-shell scattering it does not rule out a power-like behavior of the total cross sections. We discuss the
behavior of the total cross section of virtual photon–proton scattering in the geometrical approach and obtain the result
that the exponent of the power-like energy dependence of is related to the constituent quark interaction radius. The mass effects and energy dependence of vector meson electroproduction
are discussed along with the angular distributions at large momentum transfers in these processes.
Received: 10 September 2001 / Published online: 7 December 2001 相似文献
15.
P. Patrício M. Tasinkevych M.M. Telo da Gama 《The European physical journal. E, Soft matter》2002,7(2):117-122
We use a two-dimensional (2D) elastic free energy to calculate the effective interaction between two circular disks immersed
in smectic-C films. For strong homeotropic anchoring, the distortion of the director field caused by the disks generates topological
defects that induce an effective interaction between the disks. We use finite elements, with adaptive meshing, to minimize
the 2D elastic free energy. The method is shown to be accurate and efficient for inhomogeneities on the length scales set
by the disks and the defects, that differ by up to 3 orders of magnitude. We compute the effective interaction between two
disk-defect pairs in a simple (linear) configuration. For large disk separations, D, the elastic free energy scales as ∼D
-2, confirming the dipolar character of the long-range effective interaction. For small D the energy exhibits a pronounced minimum. The lowest energy corresponds to a symmetrical configuration of the disk-defect
pairs, with the inner defect at the mid-point between the disks. The disks are separated by a distance that is twice the distance
of the outer defect from the nearest disk. The latter is identical to the equilibrium distance of a defect nucleated by an
isolated disk.
Received 26 October 2001 and Received in final form 14 December 2001 相似文献
16.
We demonstrate an optical limiter for ultra-short (∼100-fs) laser pulses. The device has a dynamic range (= damage energy/onset-of-limiting
energy) of more than 10000 and an onset-of-limiting energy of only ∼10 nJ. The output-pulse energy is kept below 1.3 μJ. The
limiting mechanism is based on two-photon absorption and refractive nonlinearities in a 20-mm piece of ZnSe. We discuss the
importance of the different nonlinearities, damage issues, and guidelines for the construction of the device.
Received: 20 December 2001 / Revised version: 25 March 2002 / Published online: 8 May 2002 相似文献
17.
A measurement is presented of dijet and 3-jet cross sections in low- diffractive deep-inelastic scattering interactions of the type , where the system X is separated by a large rapidity gap from a low-mass baryonic system Y. Data taken with the H1 detector at HERA, corresponding to an integrated luminosity of 18.0 pb, are used to measure hadron level single and double differential cross sections for and . The energy flow not attributed to jets is also investigated. The measurements are consistent with a factorising diffractive
exchange with trajectory intercept close to 1.2 and tightly constrain the dominating diffractive gluon distribution. Viewed
in terms of the diffractive scattering of partonic fluctuations of the photon, the data require the dominance of over states. Soft colour neutralisation models in their present form cannot simultaneously reproduce the shapes and the normalisations
of the differential cross sections. Models based on 2-gluon exchange are able to reproduce the shapes of the cross sections
at low values.
Received: 21 December 2000 / Published online: 6 April 2001 相似文献
18.
Q.S. Hu H. Zheng 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(3):255-262
A new perturbation approach is developed for single- and many-electron Holstein model in one-, two-, and three-dimension.
The results show that this approach has a good agreement with the Migdal theory in the adiabatic regime when the coupling
is moderate (λ < 1), but with the Lang-Firsov theory in the antiadiabatic regime ( ω/W≫ 1). In the intermediate region, our approach can describe the transition from a large-polaron Fermi-liquid to the small-polaron,
and this transition may be discontinuous in adiabatic regime, which means a phase transition appears in many-electron system.
In single-electron case, we eliminate the abrupt transition using the degenerate perturbation theory, and the calculated ground
state energy and effective mass are successfully compared with those of previous authors. Besides, the method has the advantage
of requiring little computational effort.
Received 27 December 2001 / Received in final form 8 April 2002 Published online 31 July 2002 相似文献
19.
M.R. Atayan et al. 《The European Physical Journal C - Particles and Fields》2001,21(2):271-279
The transverse energy carried by charged hadrons and by mesons is studied in interactions of and K mesons with protons and nuclei at 250 GeV/c. The data obtained on transverse energy flow at mid-rapidity can be described by the FRITIOF7.0 model with tuned parameters.
Received: 7 May 2001 / Revised version: 9 May 2001 / Published online: 19 July 2001 相似文献
20.
A. Ozawa 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):163-167
Recent experimental results concerning interaction cross-sections ( σI) are reviewed. The σI values were measured by a transmission method using the fragment separator at GSI. The σI values for B, C, N, O and F isotopes and the recently measured σI for Ar are presented. As related topics, an analysis by the recently developed Glauber model for a few-body system is introduced.
By using this analysis, the effective density distributions for light neutron-rich nuclei can be deduced. The recently shown
magic number N = 16 near to the neutron drip line is also discussed.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献