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41.
A method is proposed for designing a two-dimensional randomly rough Dirichlet surface that, when illuminated at normal incidence, scatters a scalar plane wave with a specified angular distribution of its intensity. The method is validated by computer simulation calculations. 相似文献
42.
K. A. Aniol M. B. Epstein E. Gama D. J. Margaziotis W. Bertozzi J. P. Chen D. Dale R. E. J. Florizone S. Gilad A. J. Sarty J. A. Templon S. P. Van Verst J. Zhao Z. -L. Zhou P. Bartsch W. U. Boeglin R. Boehm M. O. Distler I. Ewald J. M. Friedrich J. M. Friedrich R. Geiges P. Jennewein M. Kahrau K. W. Krygier A. Liesenfeld H. Merkel K. Merle U. Muller R. Neuhausen E. A. J. M. Offermann Th. Pospischil G. Rosner H. Schmieden A. Wagner Th. Walcher M. Kuss A. Richter G. Schrieder K. Bohinc M. Potokar S. Širca J. M. Udias Javier R. Vignote R. Schiavilla 《The European Physical Journal A - Hadrons and Nuclei》2004,22(3):449-454
We have measured the 4He(e, ep)3H reaction at missing momenta of 130-300 MeV/c using the three-spectrometer facility at the Mainz microtron MAMI. Data were taken in perpendicular kinematics to allow us to determine the response function RLT and the asymmetry term ATL. The data are compared to both relativistic and non-relativistic calculations. 相似文献
43.
Recent analyses of cosmological data suggest the presence of an extra relativistic component beyond the Standard Model content. The Higgs–Dilaton cosmological model predicts the existence of a massless particle – the dilaton – associated with the spontaneous symmetry breaking of scale invariance and undetectable by any accelerator experiment. Its ultrarelativistic character makes it a suitable candidate for contributing to the effective number of light degrees of freedom in the Universe. In this Letter we analyze the dilaton production at the (p)reheating stage right after inflation and conclude that no extra relativistic degrees of freedom beyond those already present in the Standard Model are expected within the simplest Higgs–Dilaton scenario. The elusive dilaton remains thus essentially undetectable by any particle physics experiment or cosmological observation. 相似文献
44.
José F. Cariñena Javier de Lucas Manuel F. Rañada 《International Journal of Theoretical Physics》2011,50(7):2114-2124
A geometric approach is used to study the Abel first-order differential equation of the first kind. The approach is based
on the recently developed theory of quasi-Lie systems which allows us to characterise some particular examples of integrable
Abel equations. Second order Abel equations will be discussed and the inverse problem of the Lagrangian dynamics is analysed:
the existence of two alternative Lagrangian formulations is proved, both Lagrangians being of a non-natural class. The study
is carried out by means of the Darboux polynomials and Jacobi multipliers. 相似文献
45.
A particle phi coupling to two photons couples also radiatively to charged particles, like protons. If the particle is a light scalar, this induced coupling leads to spin-independent non-Newtonian forces. We show that the experimental constraints on exotic, fifth-type forces lead to stringent constraints on the phigammagamma coupling. We discuss the impact on the recent PVLAS results and the role of paraphoton models introduced to solve the PVLAS-CAST puzzle. 相似文献
46.
José P.B. Silva Koppole C. Sekhar Sofia A.S. Rodrigues Anatoli Khodorov Javier Martín-Sanchez Mário Pereira Maria J.M. Gomes 《Current Applied Physics》2012,12(4):1144-1147
The effect of pulse amplitude on the ferroelectric and switching properties of pulsed laser deposited Ba0.8Sr0.2TiO3 thin films has been studied. The structural and morphological analysis revealed that the films had a well crystallized perovskite phase and grain size of about 30–40 nm. A well saturated P–E hysteresis loop was observed with a remnant polarization (Pr) ≈ 4.8 μC/cm2 and a coercive field ≈ 100 kV/cm at a frequency of 1 kHz. The Pr has been found to be decreased only 4.3% after passing 8.0 × 108 cycles. The analysis of switching response with nucleation limited switching model reveals that characteristic switching time (t0) variance is due to the random distribution of the local electric fields. The peak value of polarization current and t0 exhibits exponential dependence on reciprocal of pulse amplitude. 相似文献
47.
Design and performance of BOREAS,the beamline for resonant X‐ray absorption and scattering experiments at the ALBA synchrotron light source 下载免费PDF全文
Alessandro Barla Josep Nicolás Daniele Cocco Secundino Manuel Valvidares Javier Herrero-Martín Pierluigi Gargiani Jairo Moldes Claude Ruget Eric Pellegrin Salvador Ferrer 《Journal of synchrotron radiation》2016,23(6):1507-1517
The optical design of the BOREAS beamline operating at the ALBA synchrotron radiation facility is described. BOREAS is dedicated to resonant X‐ray absorption and scattering experiments using soft X‐rays, in an unusually extended photon energy range from 80 to above 4000 eV, and with full polarization control. Its optical scheme includes a fixed‐included‐angle, variable‐line‐spacing grating monochromator and a pair of refocusing mirrors, equipped with benders, in a Kirkpatrick–Baez arrangement. It is equipped with two end‐stations, one for X‐ray magnetic circular dichroism and the other for resonant magnetic scattering. The commissioning results show that the expected beamline performance is achieved both in terms of energy resolution and of photon flux at the sample position. 相似文献
48.
Francisco Javier González Javier Alda Jorge Simón James Ginn Glenn Boreman 《Infrared Physics & Technology》2009,52(1):48-51
In this paper the optical parameters at infrared frequencies of metallic thin films were obtained experimentally using a variable angle spectroscopic ellipsometer and used to simulate numerically the frequency response of antennas and antenna-coupled detectors at infrared frequencies (5–15 μm). The simulation results agree with previously published data and practical guidelines are presented for the design and fabrication of dipole and bowtie antennas at infrared frequencies. 相似文献
49.
Prof. Dr. Javier A. Cabeza Dr. Pablo García-Álvarez Prof. Dr. Mar Gómez-Gallego Laura González-Álvarez Alba D. Merinero Prof. Dr. Miguel A. Sierra 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(36):8635-8642
The reactivity of amidinatotetrylenes of the type E(tBu2bzm)R1 (E=Si, Ge; tBu2bzm=N,N′-bis(tertbutyl)benzamidinate; R1=alkyl or aryl) with the chromium Fischer alkynylcarbene complexes [Cr{C(OEt)C2R2}(CO)5] (R2=Ph; ferrocenyl, Fc) has been studied. At room temperature, two different reaction pathways have been identified: (a) attack of the amidinatotetrylene to the alkynyl C2 atom (γ-attack), which leads to σ-allenyl complexes in which the original Ccarbene atom maintains its attachment to the Cr(CO)5 and OEt groups (compounds 3 ), and (b) attack of the amidinatotetrylene to the Ccarbene atom (α-attack), which ends in σ-allenyl complexes in which the original Ccarbene atom is not attached to the metal atom and has been inserted into an E−N bond of the amidinatotetrylene forming an E-C-N-C-N five-membered ring (compounds 4 ). It has been found that compounds 3 are thermodynamically less stable than their corresponding 4 isomers and that some of the former (E=Ge; R1=CH2SiMe3) can be transformed into the latter upon heating. At high temperatures (>70 °C) the reactions involving bulky amidinatotetrylenes (R1=Mes, tBu) end in the carbene-substitution products [Cr{E(tBu2bzm)R1}(CO)5]. 相似文献
50.