A "Wavelength Shifter" for the University of Wisconsin Electron Storage Ring

In order to enhance the synchrotron radiation experimental program at the University of Wisconsin Physical Sciences Laboratory, a series of three magnets is being designed to be inserted in a long straight section of the 240 MeV electron storage ring. Two of these magnets (each with a 12.5 kG peak field for a 4° bend) will be inverted so as to deflect the equilibrium orbit 1 cm radially away from the ring center. The central magnet will have a maximum field of about 25 kG and will turn the beam through 8°. The synchrotron radiation power spectrum from this central high field magnet will peak at 40 Å. Using the Courant and Snyder formalism, tune shifts of ¿¿x = 0.028 and ¿¿z=0.024 have been calculated for an optimum design -- all magnets are to be wedge shaped for normal beam entry and exit at full excitation and each of the magnets will have a constant field gradient of n = 1/3. Stopband widths at nearby resonances have been calculated to be ¿0.057 and are considered to be quite tolerable. Calculations have also been carried out to insure that the "wavelength shifter" does not adverseley affect the synchrotron radiation damping rates. For the optimum design, the maximum change to the damping rates will be less than 10%.