共查询到20条相似文献,搜索用时 15 毫秒
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Physics of Atomic Nuclei - Investigation of lepton propagation through matter is of importance for cosmic-ray physics and neutrino astronomy. The diffractive scattering of virtual photons is... 相似文献
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The characteristic features of the polarization bremsstrahlung (PBS) of fast electrons moving in a medium of light elements with a well-defined atomic shell structure are examined. Here the PBS acquires a particular structure split by two (high- and low-frequency) coherent regions, which is especially pronounced for elements with atomic numbers Z < 10. The PBS spectrum as a whole, unlike the previous predictions, is displaced toward lower frequencies. The frequency ranges of partially and fully coherent PBS are indicated. 相似文献
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U. Timm 《Fortschritte der Physik》1969,17(12):765-808
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The polarization bremsstrahlung of a fast charged particle in a medium is considered for the case where the conditions for two resonances are satisfied simultaneously: the photon frequency is close to the frequency of one of the transitions of the medium atom, and the permittivity of the medium at this frequency meets the conditions of appearance of Cerenkov radiation. As this takes place, the radiation intensity becomes three or four orders of magnitude higher than that associated with the frequency band within which the bremsstrahlung photon energy exceeds the ionization energy of the atom. Estimates are made for an experiment performed on a gas atomic parahelium at frequencies close to that of the 1s-2p transition. 相似文献
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Universal relations have been derived to describe the spectral-angular dependence of the polarization bremsstrahlung of a fast charged particle, based on a statistical model for the electron skeleton of the target. Three statistical atomic models are considered in terms of which the target characteristics that determine the cross section for polarization bremsstrahlung are calculated and analyzed. 相似文献
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M. I. Mazuritskiy A. M. Lerer A. Marcelli S. B. Dabagov M. Coreno A. D’Elia 《JETP Letters》2018,107(10):600-605
The diffraction of long-wavelength X rays with the energy corresponding to the region of anomalous dispersion near the Si L2,3 absorption edges transmitted through microchannel plates has been studied both experimentally and theoretically. The radiation of a finite antenna array, as well as the processes of excitation of X-ray fluorescence and propagation of waves in hollow waveguide structures, has been mathematically simulated. The model describes a polycapillary structure consisting of noninteracting emitters, which are hollow channels of a microchannel plate. It has been shown that coherently excited X-ray fluorescence propagates primarily in the direction of the zeroth diffraction order. 相似文献
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John Argyris Corneliu Ciubotariu Ioannis Andreadis 《Foundations of Physics Letters》1998,11(3):277-285
Applying the tangent dynamics technique as generated by infinitesimal Lorentz transformations, it is shown that the components of an electromagnetic field correspond to the Lie-Cartan parameters of the group SO(3,1). Thus the maximum number of non-null components of the magnetic field (i.e., the number of the states of polarization) is not decided by the number of group generators. 相似文献
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A. A. Rodionov A. V. Oginov K. V. Shpakov 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(4):404-408
Scintillation detectors for detecting X-ray, gamma, and neutron radiation with time resolutions of 3–4 ns and having high noise stability have been developed. The detector housings are shielded from the strong electromagnetic interference produced at the moment of discharge. The detector design features an original voltage divider. With these detectors, the parameters of the high-energy radiation from a megavolt atmospheric nanosecond discharge can be studied at the limit of sensitivity of this class of devices. 相似文献
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It has been predicted that a driven three-level V atom can emit strongly correlated fluorescence photons in the presence of quantum interference. Here we examine the effects of quantum interference on the intensity correlation of fluorescence photons emitted from a driven three-level A atom. Unexpectedly, strong correlation occurs without quantum interference. The quantum interference tends to reduce the correlation function to a normal level. The essential difference between these two cases is traced to the different effects of quantum interference on coherent population trapping (OPT). For the V atom, quantum interference and coherent excitation combine to lead to OPT. For the A atom, however, the quantum interference tends to spoil OPT while the coherent excitation induces the effect. 相似文献
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提出一个新颖的射频电子束团序列在偏转或者摇摆磁场中发射的相干同步辐射相干迭加导致辐射增强的理论模型,并基此分析和计算了利用BFEL装置的3?0MeV射频直线加速器产生的电子束团序列发射的相干辐射增强效应.由讨论可知,不同的束团产生的相干同步辐射之间存在相干性源于束团间的相干性;这种束团间的相干性引起的辐射增强迭加在单个束团产生的相干辐射功率谱上;随着波长的增长,这种辐射增强呈现规则的高速振荡效应;束团间相干性引起的强度增强近似约为宏脉冲内所含束团数的平方.最后提出利用所设计的毫米波Michelson干涉仪检测BFEL装置的电子束团序列的相干性的实验设想. 相似文献
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Technical Physics - Evolution of bunching and harmonic power is theoretically studied for a single-pass free-electron laser (FEL) in which electrons are periodically phase-shifted relative to... 相似文献
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Blazhevich S. V. Grishin V. K. Ishkhanov V. S. Nasonov N. N. Petukhov V. P. Chepurnov A. S. Shvedunov V. I. 《Russian Physics Journal》2001,44(3):276-280
The polarization bremsstrahlung (PBS) generated by relativistic charged particles in a dense medium represents a new and important problem in the radiation physics of charged particles. In the present paper, the results of experimental investigations of PBS conducted with the linear electron accelerator developed at the Scientific Research Institute for Nuclear Physics at Moscow State University (SRINP MSU) are presented; the specific features of spectral and angular PBS distribution in an amorphous and polycrystalline target and directions for their further study are discussed. 相似文献
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K. A. Barantsev A. N. Litvinov E. N. Popov 《Journal of Experimental and Theoretical Physics》2017,125(6):993-1004
A theory of excitation of a coherent population trapping resonance in hot alkali-metal atoms in a cell with buffer gas is constructed, taking into account the finite spectral width of two-component radiation, its vector properties, and the hyperfine and Zeeman structures of atoms. The propagation of intermode correlations in an optically dense gas cell is studied. It is found that in the case of partially correlated input modes, their correlation degree at the output can increase. This effect can be used for filtering the incoherent part of radiation. 相似文献
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Polarization characteristics of diffraction radiation generated by charged particles moving close to a tilted conducting half-plane or passing through a slit are studied. Unlike the linearly polarized transition radiation, the diffraction radiation is shown to possess elliptical polarization. The dependence of three Stokes parameters of diffraction radiation on the distance to the slit center is analyzed for the case of a particle passing through a slit. A method for determining the transverse beam size while measuring the diffraction radiation polarization is proposed. 相似文献