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1.
P. Paasche T. Valenzuela D. Biswas C. Angelescu G. Werth 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):295-300
We have examined experimentally the motional spectrum of an electron cloud confined in a Penning trap. When the axial oscillation
is excited by a radio frequency field the resonance exhibits a double structure. Both components depend differently on the
number of trapped electrons and have different shape and width. We conclude that one of them corresponds to the excitation
of the individual electrons while the other is the center-of-mass mode of the cloud. The threshold behaviour of the center-of-mass
resonance suggests that it is a parametric instability of a Mathieu type equation of motion.
Received 11 July 2001 and Received in final form 12 November 2001 相似文献
2.
P. Paasche C. Angelescu S. Ananthamurthy D. Biswas T. Valenzuela G. Werth 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(2):183-188
We have measured the storage instabilities of electrons in a Penning trap at low magnetic fields. These measurements are carried
out as a function of the trapping voltage, for different magnetic fields. It is seen that these instabilities occur at the
same positions when the trapping voltage is expressed as a percentage of the maximum voltage, given by the stability limit.
The characteristic frequencies at which these instabilities occur, obey a relation that is given by n
zω
z + n
+ω
+ + n
-ω
- = 0, where ω
z, ω
+ and ω
- are the axial, perturbed cyclotron and the magnetron frequencies of the trapped electrons respectively, and the n's are integers. The reason for these instabilities are attributed to higher order static perturbations in the trapping potential.
Received 5 August 2002 / Received in final form 14 October 2002 Published online 17 December 2002
RID="a"
ID="a"Present address: Dept. of Physics, Rampurhat College, Rampurhat, Birbhum, West Bengal, India.
RID="b"
ID="b"e-mail: werth@mail.uni-mainz.de 相似文献
3.
R. Wilfinger J. Lettry A. Fabich H. Aiginger K. Poljanc R. Catherall M. Eller 《The European physical journal. Special topics》2007,150(1):373-378
Thermal stress-waves are generated in the solid target
material when the proton beam interacts. These stress waves excite
natural oscillations of the target or cause plastic deformations.
Hence, an experimental setup with a laser Doppler vibrometer
[CITE] was developed to investigate free surface
vibrations of cylindrical targets. The target configurations for
RIB and conventional neutrino beams (CNGS project) were
investigated to analyze proton induced thermal stress-wave
generation and propagation. 相似文献
4.
S. Rahaman V.-V. ElomaaT. Eronen J. HakalaA. Jokinen J. JulinA. Kankainen A. SaastamoinenJ. Suhonen C. WeberJ. Äystö 《Physics letters. [Part B]》2008
Penning trap measurements using mixed beams of 76Ge–76Se and 100Mo–100Ru have been utilized to determine the double-beta decay Q-values of 76Ge and 100Mo with uncertainties less than 200 eV. The value for 76Ge, 2039.04(16) keV is in agreement with the published SMILETRAP value, 2039.006(50) keV. The new value for 100Mo, 3034.40(17) keV is 30 times more precise than the previous literature value, sufficient for the ongoing neutrinoless double-beta decay searches in 100Mo. Moreover, the precise Q-value is used to calculate the phase-space integrals and the experimental nuclear matrix element of double-beta decay. 相似文献
5.
D. Lognoli G. Cecchi I. Mochi L. Pantani V. Raimondi R. Chiari T. Johansson P. Weibring H. Edner S. Svanberg 《Applied physics. B, Lasers and optics》2003,76(4):457-465
Extensive fluorescence multispectral imaging of the cathedral and baptistery of Parma, Italy, is reported and discussed. In
particular, the first fluorescence imaging data from protection-treated stony materials were recorded. Fluorescence spectra
were taken with a mobile lidar system scanning the monument surfaces with a frequency-tripled Nd:YAG laser beam from a distance
of about 80 m. For each pixel of the area investigated, a high-spectral-resolution spectrum in the full visible range was
acquired. The principal-component analysis technique was used to obtain thematic maps that outlined areas subject to protective
treatment and biological growth, and other features, such as different types of stones and decoration pigments.
Received: 24 July 2002 / Revised version: 16 January 2003 / Published online: 3 April 2003
RID="*"
ID="*"Corresponding author. Fax: +39-055/410-893, E-mail: g.cecchi@ifac.cnr.it 相似文献
6.
X. Wang A. Boselli L. D’Avino R. Velotta N. Spinelli P. Bruscaglioni A. Ismaelli G. Zaccanti 《Applied physics. B, Lasers and optics》2005,80(4-5):609-615
A Monte Carlo-based evaluation of the multiple-scattering influence on ground-based Raman lidar measurements is presented.
The lidar returns from cirrus clouds are analyzed in order to evaluate vertical profiles of the extinction and backscattering
coefficients. Results show that for the typical cirrus cloud, the presence of the multiple scattering can lead to an underestimation
of the extinction coefficient by as large as 200% whereas the backscattering coefficient is almost unaffected for the Raman
lidar technique. An algorithm to select one or a set of phase functions which fit to the lidar data is also presented. It
is an iterative procedure based on Monte Carlo scattering simulation. By comparison of the experimental value of the lidar
ratio, corrected for the multiple scattering influence, and the phase function used in the Monte Carlo simulation, one can
determine a suitable phase function. The validity and sensitivity of the algorithm have been demonstrated by applying it to
simulated cases. The application to some real cases indicates that our procedure allows for the establishing of a practical
scattering model for the cirrus clouds. 相似文献
7.
Effect of angle of incidence on self-mixing laser Doppler velocimeter and optimization of the system 总被引:1,自引:0,他引:1
Wei Huang Huaqiao Gui Liang Lu Jianping Xie Hai Ming Deyong He Huanqin Wang Tianpeng Zhao 《Optics Communications》2008,281(6):1662-1667
Based on the theory of speckle and self-mixing interference in laser-diode, three-facet cavity model is introduced to analyze laser Doppler effect based on self-mixing interference in the case of a rough surface, and numerical solution of the signal is obtained. Simulation results of speckle-modulated Doppler signal based on self-mixing effect and tracking accuracy at different incident angles are given using parameters employed in the experiment. Simulation results indicate incident angle of around 30° is most suitable when both tracking accuracy and signal amplitude are considered. Experimental waveforms agree well with simulation results, and similar conclusions as simulation predictions about changing trend of tracking accuracies of the system at different incident angles can be made. Combining with difference frequency analog phase-lock loop (PLL) technique and appropriate sampling time, a laser Doppler velocimeter with tracking accuracy better than 1.3% in the range of 10-470 mm/s is realized. 相似文献
8.
M. S. Johansen P. Alstrom J. Borg M. T. Levinsen 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,11(4):665-676
Significant statistical bias in LDA measurements and how to adequately deal with it is a subtle problem when dealing with
turbulent flows. In order to attempt a clarification we have performed measurements on a non-standard “grid experiment” where
a clear bias effect is found. We have investigated the effect of several corrective measures and find that best results, in
the sense of having the first moment converge to zero, are obtained when using the time between events as statistical weights.
The corrected time series have been used to check for extended self-similarity (ESS). Even though no scaling regime is seen
for the third moment and the flow certainly is neither isotropic nor homogeneous, perfect ESS scaling based on the absolute
third moment is observed up to the twelfth moment, extending into a time domain regime where the Taylor hypothesis of frozen
turbulence is obviously violated. Reversing the argument this indicates that the correction scheme needed can be experimentally
decided on using the criterion stated above and especially so if ESS is to be expected. Finally we have used the corrected
data to quantify the deviations from Gaussian behavior of the velocity difference probability density function for a weakly
turbulent flow. Through comparison with results on the Gaussian-Lorentzian distribution we find that the even part of the
experimental distribution can be reproduced quite well by a single-parameter family of distributions with second moment equal
unity.
Received 5 August 1998 and Received in final form 21 December 1998 相似文献
9.
New physical techniques for IC functional analysis of on-chip devices and interconnects 总被引:1,自引:0,他引:1
Christian Boit 《Applied Surface Science》2005,252(1):18-23
Localization of functional fails in ICs makes use of physical interactions that the devices produce under electrical operation. The focus is on electroluminescence (keyword: photon emission) and signal responses to stimulation by scanned beams of laser light or particles. In modern chip technologies access of this information is only available through chip backside. This paradigm shift requires a full revision of chip analysis techniques and processes. This has also been a kick-off of a rush in development of new methodologies. Here, an overview is given which parameters are crucial for successful analysis techniques of the future and how photon emission, laser based techniques and new preparation techniques based on focused ion beam (FIB) open the path into this direction. 相似文献
10.
P. Désesquelles T. M. H. Ha K. Hauschild A. Korichi F. Le Blanc A. Lopez-Martens A. Olariu C. M. Petrache 《The European Physical Journal A - Hadrons and Nuclei》2009,40(2):237-248
Modern coaxial and planar HPGe detectors allow a precise determination of the energies and trajectories of the impinging gamma-rays.
This entails the location of the gamma interactions inside the crystal from the shape of the delivered signals. This paper
reviews the state of the art of the analysis of the HPGe response function and proposes methods that lead to optimum signal
decomposition. The generic matrix method allows fast location of the interactions even when the induced signals strongly overlap. 相似文献