Reliable and precise methods for non-invasive diagnostics of sub-picosecond electron bunches are required for new accelerator facilities (FEL, LWFA, et al.). Measurements of spectral characteristics of coherent radiation generated by such bunches using interferometer allow to determine a bunch length [1]. Here we present a compare experimental study between the measurement from the double diffr...

First real-time studies of ultra-fast processes by single-bunch imaging at the European Synchrotron Radiation Facility are reported. By operating the storage ring of the ESRF in single-bunch mode with its correspondingly increased electron bunch charge density per singlet, the polychromatic photon flux density at insertion-device beamlines is sufficient to capture hard X-ray images exploiting t...

Bunch shape is one of the most important and interesting characteristics of a beam in ion linear accelerators. Recently detectors of bunch shape with a transverse scanning of low energy secondary electrons found application in several accelerators. The principle of operation of the detectors is based on a coherent transformation of a longitudinal structure of a beam under study into a transvers...

The beam lifetime in electron storage rings concerns machines running in decay mode as well as machines doing topup. A standard procedure to increase the lifetime is via bunch lengthening as the lifetime depends on the electron density in the bunch. Bunch lengthening is typically achieved with higher harmonic (Landau) cavities. As noted in [1], there are several advantages in using a different ...

The longitudinal phase space of an electron bunch in a storage ring is usually described by the bunch length c, and the energy spread cr,. The equilibrium values of these quantities are determined by a balance of damping and quantum excitation stemming from the emission of synchrotron radiation. However, the presence of longitudinal wake fields lead to a correlationbetween energy and position i...

We study the feasibility of generating femtosecond duration Free-Electron Laser with a variable photon energy from 1.5 to 48 keV, using an electron bunch with the same characteristics of the LINAC Coherent Light Source (LCLS) bunch, and a planar undulator with additional focusing. We assume that the electron bunch energy can be changed, and the undulator has a variable gap, allowing a variable ...

This paper presents recent observations obtained on the study of electron cloud induced instabilities and emittance growth on positron beams at the Cornell Electron-Positron Storage Ring Test Acceleartor (CesrTA), and the simulation of these phenomena under similar beam conditions using the program CMAD. Results show that the transition to large bunch oscillations ocurrs at similar electron clo...

and let α1, . . . , αn be its roots, which are assumed to be distinct. By definition, the Galois Group G of this equation consists of those permutations of the roots which preserve all relations between them. Equivalently, G is the set of all those permutations σ of the symbols {1, 2, . . . , n} such that φ(ασ(1), . . . , ασ(n)) = 0 for every n-variable polynomial φ for which φ(α1, . . . , αn) ...

We have counted the number of references in 1179 papers published in Astronomy and Astrophysics over twenty years. The number of references has increased by 60% between 1975 and 1995, reflecting the increase (by the same amount) of the literature which must be cited, and of the number of pages per paper. There are 1.5 timesmore references in predominantly observational fields than in others. Re...