March 5th, 2018

лошадь, диаграмма, Фейнман

Сегодня я узнал...

что скорость света обозначается словами celerity of light. Это Коэн-Танноуджи какую-то речь о фундаментальных константах толкнул:

Lambda, the Fifth Foundational Constant Considered by Einstein: https://arxiv.org/abs/1802.08317

The cosmological constant, usually named Lambda, was introduced by Einstein in 1917 and abandoned by him as his biggest "blunder". It currently seems to make a spectacular comeback in the framework of the new cosmological standard model. One will explain why, together with the Planck's constant, the Boltzmann's constant, the celerity of light and the Newton's constant, also considered by Einstein, the cosmological constant may play a foundational role in the conceptual framework, an in the metrological framework a role comparable with the one attributed to Avogadro number
лошадь, диаграмма, Фейнман

Продольная диагностика банча с помощью спектроскопии когерентного переходного излучения

Очень подробно, на 60 страниц!!!

Longitudinal Bunch Diagnostics using Coherent Transition Radiation Spectroscopy: https://arxiv.org/abs/1803.00608

The generation and properties of transition radiation (TR) are thoroughly treated. The spectral energy density, as described by the Ginzburg-Frank formula, is computed analytically, and the modifications caused by the finite size of the TR screen and by near-field diffraction effects are carefully analyzed. The principles of electron bunch shape reconstruction using coherent transition radiation are outlined. Spectroscopic measure- ments yield only the magnitude of the longitudinal form factor but not its phase. Two phase retrieval methods are investigated and illustrated with model calculations: analytic phase computation by means of the Kramers- Kronig dispersion relation, and iterative phase retrieval. Particular attention is paid to the ambiguities which are unavoidable in the reconstruction of longitudinal charge density profiles from spectroscopic data. The origin of these ambiguities has been identified and a thorough mathematical analysis is presented. The experimental part of the paper comprises a description of our multichannel infrared and THz spectrometer and a selection of measurements at FLASH, comparing the bunch profiles derived from spectroscopic data with those determined with a transversely deflecting microwave structure. A rigorous derivation of the Kramers-Kronig phase formula is presented in Appendix A. Numerous analytic model calculations can be found in Appendix B. The differences between normal and truncated Gaussians are discussed in Appendix C. Finally, Appendix D contains a short description of the propagation of an electromagnetic wave front by two-dimensional fast Fourier transformation. This is the basis of a powerful numerical Mathematica code THzTransport, which permits the propagation of electromagnetic wave fronts through a beam line consisting of drift spaces, lenses, mirrors and apertures.