GeV Electron Storage Ring Research Articles

Design of a vertical wiggler with superconducting coils

A vertical wiggler has been designed, which will be installed in the 2.5 GeV electron storage ring under construction at KEK-PF. The wiggler magnet with superconducting coils produces magnetic fields of 6 T and wiggles electron beams in a vertical plane. Synchrotronn radiation generated by the wiggler has a critical wavelength of 0.5 Å and has an electric field-vector in the vertical direction, which is very important for precise experiments in various fields of the material sciences. The wiggler consists of three pairs of superconducting coils, an iron magnetic shield, a beam pipe and a liquid helium cryogenic system and is contained in a vacuum vessel which can move up and down together with the wiggler. During the injection time, the vessel is pushed up, so that electron beams with a large spatial spread go through the lower part of the beam pipe, where the aperture of the beam pipe is large enough. After the beam size becomes small due to radiation damping, the vessel is pushed down so that the electron beams go through the narrow gap of the wiggler magnet. Using the iron magnetic shield with iron pole pieces, the ratio between the magnetic field in the gap and the maximum field on the superconductor coils is reduced to 1.1.

Current limitations due to RF parameters in the photon factory storage ring

The threshold current is estimated for the longitudinal and transverse bunch instability in the Photon Factory 2.5 GeV electron storage ring by assuming the most probable ring impedances. It is of the order of 100 mA for the longitudinal bunch turbulence. If no chromaticity-correction is made, currents of only about 3 mA will induce the zero-mode head-tail instability. Hence the chromaticity should be around zero. For multibunch operation with a mean current of 500 mA, the higher-mode resonances of the accelerating cavity should be dampled by about 20 dB in order to suppress the coupled-bunch instability for both longitudinal and transverse oscillations.

Progress report on the SRS at Daresbury

The design of the 2 GeV electron storage ring is complete and construction is well advanced. Many of the components have been delivered and tested and results of magnet and cavity measurements, for instance, can now be given. Beam line design is well advanced. The booster synchrotron has been commissioned and has achieved a circulating beam intensity of 40 mA at the design energy of 600 MeV with good extraction efficiency. This current comfortably exceeds minimum requirements. The 5 T superconducting wiggler magnet is under construction and tests on the centre (high field) coils should start soon.

The proposed European synchrotron radiation facility

A feasibility study has been carried out for the European Science Foundation of a 5 GeV electron storage ring intended as a very intense dedicated source of X-radiation. The specification called for beam ports with specified spectral characteristics, and for maximum intensity, brightness, and stability together with an optimum time structure for the beam. The paper will describe how the design of the storage ring was derived to meet the specification; the magnet lattice will be given, and other design features will be briefly described.

Extreme Ultraviolet Absorption Spectra of K–Rb and K–Cs alloys

The optical conductivities of K–Rb and K–Cs alloys have been measured at liquid nitrogen temperature using synchrotron radiation from a 0.4 GeV electron storage ring over the photon energy range from 10 to 30 eV. The spectra of the alloys have the profiles given by the proportional sums of the spectra of pure alkali metals and this feature suggests the localization of the excitation of outer-most p -shell electrons. The critical exponent of the Fermi edge singularity is altered by alloying. Its concentration-dependence is interpreted as indicating that the shape of spikes at the edge is affected not by the density of states but by the size of the core hole. The energy positions of the edge are shifted by alloying. The amount of the shift is dependent on the concentration and increases for increasing atomic number. This, along with the change in the exponent, may be ascribed to charge transfer effects due to alloying.

Design Status of the 2.5 GeV National Synchrotron Light Source X-Ray Ring

The present state of the design of the 2.5 GeV electron storage ring for the National Synchrotron Light Source is described. This ring will serve as a dedicated source of synchrotron radiation in the wavelength range 0.1 Å to 30 Å. While maintaining the basic high brightness features of the earlier developed lattice structure, recent work resulted in a more economical magnet system, simplified chromaticity corrections, and improved distribution of the X-ray beam lines. In addition, the adequacy of the dynamic aperture for stable betatron oscillations has been verified for a variety of betatron tunes.

A 5-tesla wiggler magnet for the SRS

The SRS is a 2 GeV electron storage ring being built as a dedicated Synchroton Radiation Source at the Daresbury Laboratory. This paper outlines the design of a 3-pole superconducting transverse wiggler magnet for installation in the storage ring. The design field of 5 T will enhance the synchroton radiation spectrum in the region 0.1 to 2 Å. Design constraints imposed by the storage ring geometry and superconductor characteristics are discussed and a specific design based on Nb-Ti superconductor is described.

An E-P Facility in the CERN SPS

A 25 GeV electron (or positron) storage ring installed in the SPS tunnel above the proton synchrotron would provide e-p collisions with a luminosity in the range of 10/sup 31/ to 10/sup 32/ cm/sup -2/ s/sup -1/. The collisions would normally take place at an intermediate plateau of the SPS-cycle up to 270 GeV, and could be followed by acceleration and extraction of the proton beam for fixed target experiments. The feasibility of such a facility is demonstrated and the essential features presented.