Synchrotron bunch

Because of the unique features of the x-ray radiation available at synchrotrons, many novel experiments ate being conducted at these sources. Some of these unique features are the very high intensity and the brightness (number of photons per unit area per second), the neatly parallel incident beam, the abihty to choose a narrow band of wavelengths from a broad spectmm, the pulsed nature of the radiation (the electrons or positrons travel in bunches), and the coherence of the beam (the x-ray photons in a pulse are in phase with one another). The appHcations are much more diverse than the appHcations described in this article. The reader may wish to read the articles in the Proceedings of the Materials Research Society Hsted in the bibhography. 

M. Dohlus and T. Limberg, Calculation of coherent synchrotron radiation in the ttf-fel bunch compressor magnet chicanes. Nucl. Instrum. Methods Phys. Res. Sect. A 407(1-3), 278-284 (1998). 

Fig. 5 Schematic diagram of the experimental setup depicting the APS bunched synchrotron radiation, the electromagnetic undulator on beamline 4-ID-C, the spherical grating monochromator and the XPS end station...

The synchrotron was developed by elementary particle physics in order to accelerate electrons, positrons, protons and other particles. It consists of a ring with a diameter of about a few meters up to more than 100 m in which a vacuum of 10 mbar can be sustained and to which strong electric and magnetic fields can be applied (see Fig. 1). A bunch of electrons or positrons is first accelerated in a linear accelerator to an energy usually lying between 40 MeV and 380 MeV. 

In a synchrotron, an electron (or positron) bunch issued from a linear accelerator is injected into a vacuum ring chamber and maintained colinear to the axis of the... 

Because the electrons in a storage ring circulate precisely in the form of a bunch, the synchrotron light produced is very stable, with subnanosecond pulses repeated on a microsecond time scale. 

Figure 2-8. One of the (16-bunch) timestructures available in the synchrotron at the ESRF, Grenoble,...

From PFI-PE spectroscopy and ion coincidence detection using multi-bunch synchrotron radiation. "From the experimental AfH°n,(C2H4) and PA(C2H4) = 162.98 kcal mol computed at the G2 level. PFI-PEPICO TOE experiments and experimental Affl°n,(g) for the various precursor species. " ... 

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