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Synchrotron Radiation X-ray Sources for Radiography and Tomography
Published in Paolo Russo, Handbook of X-ray Imaging, 2017
Giorgio Margaritondo, Fauzia Albertin
Over almost 50 years, the most advanced applications of X-rays progressively shifted from conventional sources to synchrotron facilities (Margaritondo 1988, Margaritondo 1995, Bordovitsyn and Gushchina 1999, Margaritondo 2002, Wiedemann 2003, Willmott 2011, Winick 2012). More recently, the first X-ray free-electron lasers (FELs) were commissioned (Emma et al. 2010, Saldin Schneidmiller and Yurkov 2010, Margaritondo and Rebernik Ribic 2011, Rebernik Ribic and Margaritondo 2012a,b), starting a new trend for applications that require high peak brightness and/or very short pulses.
F
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
free distance the minimum Hamming distance between two convolutionally encoded sequences that represent different valid paths through the same code trellis. The free distance equals the maximum column distance and the limiting value of the distance profile. free electron laser laser in which the active medium consists of electrons that are subject to electric and magnetic fields but are not associated with atoms or molecules.
Laser Basics
Published in Ken Barat, Laser Safety Management, 2017
Free electron lasers (FELs) such as in Figure 15.9 generate wavelengths from the microwave to the x-ray region. They operate by having an electron beam in an optical cavity pass through a wiggler magnetic field. The change in direction exerted by the magnetic field on the electrons causes them to emit photons (from nLight Inc.).
Light, the universe and everything – 12 Herculean tasks for quantum cowboys and black diamond skiers
Published in Journal of Modern Optics, 2018
Girish Agarwal, Roland E. Allen, Iva Bezděková, Robert W. Boyd, Goong Chen, Ronald Hanson, Dean L. Hawthorne, Philip Hemmer, Moochan B. Kim, Olga Kocharovskaya, David M. Lee, Sebastian K. Lidström, Suzy Lidström, Harald Losert, Helmut Maier, John W. Neuberger, Miles J. Padgett, Mark Raizen, Surjeet Rajendran, Ernst Rasel, Wolfgang P. Schleich, Marlan O. Scully, Gavriil Shchedrin, Gennady Shvets, Alexei V. Sokolov, Anatoly Svidzinsky, Ronald L. Walsworth, Rainer Weiss, Frank Wilczek, Alan E. Willner, Eli Yablonovitch, Nikolay Zheludev
In a free-electron laser, relativistic electrons are made to wiggle back and forth as they pass through an undulator consisting of magnets with alternating polarity. These accelerated charges emit radiation, which becomes increasingly intense and acts back on the electrons. A detailed treatment shows that the electrons are forced into microbunches with a spacing equal to one wavelength of the radiation. When the electrons are stopped after an appropriate distance, the radiation that emerges is then nearly monochromatic and coherent. If the electrons are extremely relativistic, the radiation can also be nearly unidirectional (~ 100 μm across) with a very short wavelength (down to ~ 1 Å at the most energetic current facilities).
The performance of approximate equation of motion coupled cluster for valence and core states of heavy element systems
Published in Molecular Physics, 2023
Loic Halbert, André Severo Pereira Gomes
Developments in electronic structure methods of recent decades [1–3] have allowed theory to play a more important role in helping interpret increasingly complex experiments. One case arises in connection to the recent developments on coherent light sources such as those generated in synchrotrons [4–7] or X-ray free-electron lasers (XFEL) [8,9], which have enabled significant improvements in resolution when exploring high-energy processes involving electronic excitations, such as in X-ray absorption spectroscopy (XAS). But theory can also be of help in lower-energy regimes, be in photoionisation experiments [10] in UV/visible energy range or in the determination of electron affinities [11–13].